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2021-02-10fgraph: Initialize tracing_graph_pause at task creationSteven Rostedt (VMware)
commit 7e0a9220467dbcfdc5bc62825724f3e52e50ab31 upstream. On some archs, the idle task can call into cpu_suspend(). The cpu_suspend() will disable or pause function graph tracing, as there's some paths in bringing down the CPU that can have issues with its return address being modified. The task_struct structure has a "tracing_graph_pause" atomic counter, that when set to something other than zero, the function graph tracer will not modify the return address. The problem is that the tracing_graph_pause counter is initialized when the function graph tracer is enabled. This can corrupt the counter for the idle task if it is suspended in these architectures. CPU 1 CPU 2 ----- ----- do_idle() cpu_suspend() pause_graph_tracing() task_struct->tracing_graph_pause++ (0 -> 1) start_graph_tracing() for_each_online_cpu(cpu) { ftrace_graph_init_idle_task(cpu) task-struct->tracing_graph_pause = 0 (1 -> 0) unpause_graph_tracing() task_struct->tracing_graph_pause-- (0 -> -1) The above should have gone from 1 to zero, and enabled function graph tracing again. But instead, it is set to -1, which keeps it disabled. There's no reason that the field tracing_graph_pause on the task_struct can not be initialized at boot up. Cc: stable@vger.kernel.org Fixes: 380c4b1411ccd ("tracing/function-graph-tracer: append the tracing_graph_flag") Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=211339 Reported-by: pierre.gondois@arm.com Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-30tracing: Fix race in trace_open and buffer resize callGaurav Kohli
commit bbeb97464eefc65f506084fd9f18f21653e01137 upstream. Below race can come, if trace_open and resize of cpu buffer is running parallely on different cpus CPUX CPUY ring_buffer_resize atomic_read(&buffer->resize_disabled) tracing_open tracing_reset_online_cpus ring_buffer_reset_cpu rb_reset_cpu rb_update_pages remove/insert pages resetting pointer This race can cause data abort or some times infinte loop in rb_remove_pages and rb_insert_pages while checking pages for sanity. Take buffer lock to fix this. Link: https://lkml.kernel.org/r/1601976833-24377-1-git-send-email-gkohli@codeaurora.org Cc: stable@vger.kernel.org Fixes: 83f40318dab00 ("ring-buffer: Make removal of ring buffer pages atomic") Reported-by: Denis Efremov <efremov@linux.com> Signed-off-by: Gaurav Kohli <gkohli@codeaurora.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-01-19tracing/kprobes: Do the notrace functions check without kprobes on ftraceMasami Hiramatsu
commit 7bb83f6fc4ee84e95d0ac0d14452c2619fb3fe70 upstream. Enable the notrace function check on the architecture which doesn't support kprobes on ftrace but support dynamic ftrace. This notrace function check is not only for the kprobes on ftrace but also sw-breakpoint based kprobes. Thus there is no reason to limit this check for the arch which supports kprobes on ftrace. This also changes the dependency of Kconfig. Because kprobe event uses the function tracer's address list for identifying notrace function, if the CONFIG_DYNAMIC_FTRACE=n, it can not check whether the target function is notrace or not. Link: https://lkml.kernel.org/r/20210105065730.2634785-1-naveen.n.rao@linux.vnet.ibm.com Link: https://lkml.kernel.org/r/161007957862.114704.4512260007555399463.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: 45408c4f92506 ("tracing: kprobes: Prohibit probing on notrace function") Acked-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30Revert: "ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS"Steven Rostedt (VMware)
commit adab66b71abfe206a020f11e561f4df41f0b2aba upstream. It was believed that metag was the only architecture that required the ring buffer to keep 8 byte words aligned on 8 byte architectures, and with its removal, it was assumed that the ring buffer code did not need to handle this case. It appears that sparc64 also requires this. The following was reported on a sparc64 boot up: kernel: futex hash table entries: 65536 (order: 9, 4194304 bytes, linear) kernel: Running postponed tracer tests: kernel: Testing tracer function: kernel: Kernel unaligned access at TPC[552a20] trace_function+0x40/0x140 kernel: Kernel unaligned access at TPC[552a24] trace_function+0x44/0x140 kernel: Kernel unaligned access at TPC[552a20] trace_function+0x40/0x140 kernel: Kernel unaligned access at TPC[552a24] trace_function+0x44/0x140 kernel: Kernel unaligned access at TPC[552a20] trace_function+0x40/0x140 kernel: PASSED Need to put back the 64BIT aligned code for the ring buffer. Link: https://lore.kernel.org/r/CADxRZqzXQRYgKc=y-KV=S_yHL+Y8Ay2mh5ezeZUnpRvg+syWKw@mail.gmail.com Cc: stable@vger.kernel.org Fixes: 86b3de60a0b6 ("ring-buffer: Remove HAVE_64BIT_ALIGNED_ACCESS") Reported-by: Anatoly Pugachev <matorola@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-30bpf: Fix bpf_put_raw_tracepoint()'s use of __module_address()Andrii Nakryiko
[ Upstream commit 12cc126df82c96c89706aa207ad27c56f219047c ] __module_address() needs to be called with preemption disabled or with module_mutex taken. preempt_disable() is enough for read-only uses, which is what this fix does. Also, module_put() does internal check for NULL, so drop it as well. Fixes: a38d1107f937 ("bpf: support raw tracepoints in modules") Signed-off-by: Andrii Nakryiko <andrii@kernel.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Martin KaFai Lau <kafai@fb.com> Link: https://lore.kernel.org/bpf/20201203204634.1325171-2-andrii@kernel.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-12-11tracing: Fix userstacktrace option for instancesSteven Rostedt (VMware)
commit bcee5278958802b40ee8b26679155a6d9231783e upstream. When the instances were able to use their own options, the userstacktrace option was left hardcoded for the top level. This made the instance userstacktrace option bascially into a nop, and will confuse users that set it, but nothing happens (I was confused when it happened to me!) Cc: stable@vger.kernel.org Fixes: 16270145ce6b ("tracing: Add trace options for core options to instances") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-11ftrace: Fix updating FTRACE_FL_TRAMPNaveen N. Rao
commit 4c75b0ff4e4bf7a45b5aef9639799719c28d0073 upstream. On powerpc, kprobe-direct.tc triggered FTRACE_WARN_ON() in ftrace_get_addr_new() followed by the below message: Bad trampoline accounting at: 000000004222522f (wake_up_process+0xc/0x20) (f0000001) The set of steps leading to this involved: - modprobe ftrace-direct-too - enable_probe - modprobe ftrace-direct - rmmod ftrace-direct <-- trigger The problem turned out to be that we were not updating flags in the ftrace record properly. From the above message about the trampoline accounting being bad, it can be seen that the ftrace record still has FTRACE_FL_TRAMP set though ftrace-direct module is going away. This happens because we are checking if any ftrace_ops has the FTRACE_FL_TRAMP flag set _before_ updating the filter hash. The fix for this is to look for any _other_ ftrace_ops that also needs FTRACE_FL_TRAMP. Link: https://lkml.kernel.org/r/56c113aa9c3e10c19144a36d9684c7882bf09af5.1606412433.git.naveen.n.rao@linux.vnet.ibm.com Cc: stable@vger.kernel.org Fixes: a124692b698b0 ("ftrace: Enable trampoline when rec count returns back to one") Signed-off-by: Naveen N. Rao <naveen.n.rao@linux.vnet.ibm.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-12-08tracing: Remove WARN_ON in start_thread()Vasily Averin
commit 310e3a4b5a4fc718a72201c1e4cf5c64ac6f5442 upstream. This patch reverts commit 978defee11a5 ("tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists") .start hook can be legally called several times if according tracer is stopped screen window 1 [root@localhost ~]# echo 1 > /sys/kernel/tracing/events/kmem/kfree/enable [root@localhost ~]# echo 1 > /sys/kernel/tracing/options/pause-on-trace [root@localhost ~]# less -F /sys/kernel/tracing/trace screen window 2 [root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on 0 [root@localhost ~]# echo hwlat > /sys/kernel/debug/tracing/current_tracer [root@localhost ~]# echo 1 > /sys/kernel/debug/tracing/tracing_on [root@localhost ~]# cat /sys/kernel/debug/tracing/tracing_on 0 [root@localhost ~]# echo 2 > /sys/kernel/debug/tracing/tracing_on triggers warning in dmesg: WARNING: CPU: 3 PID: 1403 at kernel/trace/trace_hwlat.c:371 hwlat_tracer_start+0xc9/0xd0 Link: https://lkml.kernel.org/r/bd4d3e70-400d-9c82-7b73-a2d695e86b58@virtuozzo.com Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 978defee11a5 ("tracing: Do a WARN_ON() if start_thread() in hwlat is called when thread exists") Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-18tracing: Fix the checking of stackidx in __ftrace_trace_stackQiujun Huang
[ Upstream commit 906695e59324635c62b5ae59df111151a546ca66 ] The array size is FTRACE_KSTACK_NESTING, so the index FTRACE_KSTACK_NESTING is illegal too. And fix two typos by the way. Link: https://lkml.kernel.org/r/20201031085714.2147-1-hqjagain@gmail.com Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-11-10tracing: Fix out of bounds write in get_trace_bufQiujun Huang
commit c1acb4ac1a892cf08d27efcb964ad281728b0545 upstream. The nesting count of trace_printk allows for 4 levels of nesting. The nesting counter starts at zero and is incremented before being used to retrieve the current context's buffer. But the index to the buffer uses the nesting counter after it was incremented, and not its original number, which in needs to do. Link: https://lkml.kernel.org/r/20201029161905.4269-1-hqjagain@gmail.com Cc: stable@vger.kernel.org Fixes: 3d9622c12c887 ("tracing: Add barrier to trace_printk() buffer nesting modification") Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-10ftrace: Handle tracing when switching between contextSteven Rostedt (VMware)
commit 726b3d3f141fba6f841d715fc4d8a4a84f02c02a upstream. When an interrupt or NMI comes in and switches the context, there's a delay from when the preempt_count() shows the update. As the preempt_count() is used to detect recursion having each context have its own bit get set when tracing starts, and if that bit is already set, it is considered a recursion and the function exits. But if this happens in that section where context has changed but preempt_count() has not been updated, this will be incorrectly flagged as a recursion. To handle this case, create another bit call TRANSITION and test it if the current context bit is already set. Flag the call as a recursion if the TRANSITION bit is already set, and if not, set it and continue. The TRANSITION bit will be cleared normally on the return of the function that set it, or if the current context bit is clear, set it and clear the TRANSITION bit to allow for another transition between the current context and an even higher one. Cc: stable@vger.kernel.org Fixes: edc15cafcbfa3 ("tracing: Avoid unnecessary multiple recursion checks") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-10ftrace: Fix recursion check for NMI testSteven Rostedt (VMware)
commit ee11b93f95eabdf8198edd4668bf9102e7248270 upstream. The code that checks recursion will work to only do the recursion check once if there's nested checks. The top one will do the check, the other nested checks will see recursion was already checked and return zero for its "bit". On the return side, nothing will be done if the "bit" is zero. The problem is that zero is returned for the "good" bit when in NMI context. This will set the bit for NMIs making it look like *all* NMI tracing is recursing, and prevent tracing of anything in NMI context! The simple fix is to return "bit + 1" and subtract that bit on the end to get the real bit. Cc: stable@vger.kernel.org Fixes: edc15cafcbfa3 ("tracing: Avoid unnecessary multiple recursion checks") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-10ring-buffer: Fix recursion protection transitions between interrupt contextSteven Rostedt (VMware)
commit b02414c8f045ab3b9afc816c3735bc98c5c3d262 upstream. The recursion protection of the ring buffer depends on preempt_count() to be correct. But it is possible that the ring buffer gets called after an interrupt comes in but before it updates the preempt_count(). This will trigger a false positive in the recursion code. Use the same trick from the ftrace function callback recursion code which uses a "transition" bit that gets set, to allow for a single recursion for to handle transitions between contexts. Cc: stable@vger.kernel.org Fixes: 567cd4da54ff4 ("ring-buffer: User context bit recursion checking") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-05ring-buffer: Return 0 on success from ring_buffer_resize()Qiujun Huang
commit 0a1754b2a97efa644aa6e84d1db5b17c42251483 upstream. We don't need to check the new buffer size, and the return value had confused resize_buffer_duplicate_size(). ... ret = ring_buffer_resize(trace_buf->buffer, per_cpu_ptr(size_buf->data,cpu_id)->entries, cpu_id); if (ret == 0) per_cpu_ptr(trace_buf->data, cpu_id)->entries = per_cpu_ptr(size_buf->data, cpu_id)->entries; ... Link: https://lkml.kernel.org/r/20201019142242.11560-1-hqjagain@gmail.com Cc: stable@vger.kernel.org Fixes: d60da506cbeb3 ("tracing: Add a resize function to make one buffer equivalent to another buffer") Signed-off-by: Qiujun Huang <hqjagain@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-07tracing: Make the space reserved for the pid widerSebastian Andrzej Siewior
[ Upstream commit 795d6379a47bcbb88bd95a69920e4acc52849f88 ] For 64bit CONFIG_BASE_SMALL=0 systems PID_MAX_LIMIT is set by default to 4194304. During boot the kernel sets a new value based on number of CPUs but no lower than 32768. It is 1024 per CPU so with 128 CPUs the default becomes 131072 which needs six digits. This value can be increased during run time but must not exceed the initial upper limit. Systemd sometime after v241 sets it to the upper limit during boot. The result is that when the pid exceeds five digits, the trace output is a little hard to read because it is no longer properly padded (same like on big iron with 98+ CPUs). Increase the pid padding to seven digits. Link: https://lkml.kernel.org/r/20200904082331.dcdkrr3bkn3e4qlg@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-07ftrace: Move RCU is watching check after recursion checkSteven Rostedt (VMware)
commit b40341fad6cc2daa195f8090fd3348f18fff640a upstream. The first thing that the ftrace function callback helper functions should do is to check for recursion. Peter Zijlstra found that when "rcu_is_watching()" had its notrace removed, it caused perf function tracing to crash. This is because the call of rcu_is_watching() is tested before function recursion is checked and and if it is traced, it will cause an infinite recursion loop. rcu_is_watching() should still stay notrace, but to prevent this should never had crashed in the first place. The recursion prevention must be the first thing done in callback functions. Link: https://lore.kernel.org/r/20200929112541.GM2628@hirez.programming.kicks-ass.net Cc: stable@vger.kernel.org Cc: Paul McKenney <paulmck@kernel.org> Fixes: c68c0fa293417 ("ftrace: Have ftrace_ops_get_func() handle RCU and PER_CPU flags too") Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org> Reported-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-01tracing: fix double freeTom Rix
commit 46bbe5c671e06f070428b9be142cc4ee5cedebac upstream. clang static analyzer reports this problem trace_events_hist.c:3824:3: warning: Attempt to free released memory kfree(hist_data->attrs->var_defs.name[i]); In parse_var_defs() if there is a problem allocating var_defs.expr, the earlier var_defs.name is freed. This free is duplicated by free_var_defs() which frees the rest of the list. Because free_var_defs() has to run anyway, remove the second free fom parse_var_defs(). Link: https://lkml.kernel.org/r/20200907135845.15804-1-trix@redhat.com Cc: stable@vger.kernel.org Fixes: 30350d65ac56 ("tracing: Add variable support to hist triggers") Reviewed-by: Tom Zanussi <tom.zanussi@linux.intel.com> Signed-off-by: Tom Rix <trix@redhat.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-01lockdep: fix order in trace_hardirqs_off_caller()Sven Schnelle
[ Upstream commit 73ac74c7d489756d2313219a108809921dbfaea1 ] Switch order so that locking state is consistent even if the IRQ tracer calls into lockdep again. Acked-by: Peter Zijlstra <peterz@infradead.org> Signed-off-by: Sven Schnelle <svens@linux.ibm.com> Signed-off-by: Vasily Gorbik <gor@linux.ibm.com> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01tracing: Use address-of operator on section symbolsNathan Chancellor
[ Upstream commit bf2cbe044da275021b2de5917240411a19e5c50d ] Clang warns: ../kernel/trace/trace.c:9335:33: warning: array comparison always evaluates to true [-Wtautological-compare] if (__stop___trace_bprintk_fmt != __start___trace_bprintk_fmt) ^ 1 warning generated. These are not true arrays, they are linker defined symbols, which are just addresses. Using the address of operator silences the warning and does not change the runtime result of the check (tested with some print statements compiled in with clang + ld.lld and gcc + ld.bfd in QEMU). Link: http://lkml.kernel.org/r/20200220051011.26113-1-natechancellor@gmail.com Link: https://github.com/ClangBuiltLinux/linux/issues/893 Suggested-by: Nick Desaulniers <ndesaulniers@google.com> Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01tracing: Set kernel_stack's caller size properlyJosef Bacik
[ Upstream commit cbc3b92ce037f5e7536f6db157d185cd8b8f615c ] I noticed when trying to use the trace-cmd python interface that reading the raw buffer wasn't working for kernel_stack events. This is because it uses a stubbed version of __dynamic_array that doesn't do the __data_loc trick and encode the length of the array into the field. Instead it just shows up as a size of 0. So change this to __array and set the len to FTRACE_STACK_ENTRIES since this is what we actually do in practice and matches how user_stack_trace works. Link: http://lkml.kernel.org/r/1411589652-1318-1-git-send-email-jbacik@fb.com Signed-off-by: Josef Bacik <jbacik@fb.com> [ Pulled from the archeological digging of my INBOX ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01tracing: Adding NULL checks for trace_array descriptor pointerDivya Indi
[ Upstream commit 953ae45a0c25e09428d4a03d7654f97ab8a36647 ] As part of commit f45d1225adb0 ("tracing: Kernel access to Ftrace instances") we exported certain functions. Here, we are adding some additional NULL checks to ensure safe usage by users of these APIs. Link: http://lkml.kernel.org/r/1565805327-579-4-git-send-email-divya.indi@oracle.com Signed-off-by: Divya Indi <divya.indi@oracle.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-10-01tracing: Verify if trace array exists before destroying it.Divya Indi
[ Upstream commit e585e6469d6f476b82aa148dc44aaf7ae269a4e2 ] A trace array can be destroyed from userspace or kernel. Verify if the trace array exists before proceeding to destroy/remove it. Link: http://lkml.kernel.org/r/1565805327-579-3-git-send-email-divya.indi@oracle.com Reviewed-by: Aruna Ramakrishna <aruna.ramakrishna@oracle.com> Signed-off-by: Divya Indi <divya.indi@oracle.com> [ Removed unneeded braces ] Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-09-03blktrace: ensure our debugfs dir existsLuis Chamberlain
[ Upstream commit b431ef837e3374da0db8ff6683170359aaa0859c ] We make an assumption that a debugfs directory exists, but since this can fail ensure it exists before allowing blktrace setup to complete. Otherwise we end up stuffing blktrace files on the debugfs root directory. In the worst case scenario this *in theory* can create an eventual panic *iff* in the future a similarly named file is created prior on the debugfs root directory. This theoretical crash can happen due to a recursive removal followed by a specific dentry removal. This doesn't fix any known crash, however I have seen the files go into the main debugfs root directory in cases where the debugfs directory was not created due to other internal bugs with blktrace now fixed. blktrace is also completely useless without this directory, so this ensures to userspace we only setup blktrace if the kernel can stuff files where they are supposed to go into. debugfs directory creations typically aren't checked for, and we have maintainers doing sweep removals of these checks, but since we need this check to ensure proper userspace blktrace functionality we make sure to annotate the justification for the check. Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-08-21tracing: Move pipe reference to trace array instead of current_tracerSteven Rostedt (VMware)
commit 7ef282e05132d56b6f6b71e3873f317664bea78b upstream. If a process has the trace_pipe open on a trace_array, the current tracer for that trace array should not be changed. This was original enforced by a global lock, but when instances were introduced, it was moved to the current_trace. But this structure is shared by all instances, and a trace_pipe is for a single instance. There's no reason that a process that has trace_pipe open on one instance should prevent another instance from changing its current tracer. Move the reference counter to the trace_array instead. This is marked as "Fixes" but is more of a clean up than a true fix. Backport if you want, but its not critical. Fixes: cf6ab6d9143b1 ("tracing: Add ref count to tracer for when they are being read by pipe") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> [Resolved conflict in __remove_instance()] Signed-off-by: dann frazier <dann.frazier@canonical.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-21tracing: Use trace_sched_process_free() instead of exit() for pid tracingSteven Rostedt (VMware)
commit afcab636657421f7ebfa0783a91f90256bba0091 upstream. On exit, if a process is preempted after the trace_sched_process_exit() tracepoint but before the process is done exiting, then when it gets scheduled in, the function tracers will not filter it properly against the function tracing pid filters. That is because the function tracing pid filters hooks to the sched_process_exit() tracepoint to remove the exiting task's pid from the filter list. Because the filtering happens at the sched_switch tracepoint, when the exiting task schedules back in to finish up the exit, it will no longer be in the function pid filtering tables. This was noticeable in the notrace self tests on a preemptable kernel, as the tests would fail as it exits and preempted after being taken off the notrace filter table and on scheduling back in it would not be in the notrace list, and then the ending of the exit function would trace. The test detected this and would fail. Cc: stable@vger.kernel.org Cc: Namhyung Kim <namhyung@kernel.org> Fixes: 1e10486ffee0a ("ftrace: Add 'function-fork' trace option") Fixes: c37775d57830a ("tracing: Add infrastructure to allow set_event_pid to follow children" Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-21tracing/hwlat: Honor the tracing_cpumaskKevin Hao
commit 96b4833b6827a62c295b149213c68b559514c929 upstream. In calculation of the cpu mask for the hwlat kernel thread, the wrong cpu mask is used instead of the tracing_cpumask, this causes the tracing/tracing_cpumask useless for hwlat tracer. Fixes it. Link: https://lkml.kernel.org/r/20200730082318.42584-2-haokexin@gmail.com Cc: Ingo Molnar <mingo@redhat.com> Cc: stable@vger.kernel.org Fixes: 0330f7aa8ee6 ("tracing: Have hwlat trace migrate across tracing_cpumask CPUs") Signed-off-by: Kevin Hao <haokexin@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-21ftrace: Setup correct FTRACE_FL_REGS flags for moduleChengming Zhou
commit 8a224ffb3f52b0027f6b7279854c71a31c48fc97 upstream. When module loaded and enabled, we will use __ftrace_replace_code for module if any ftrace_ops referenced it found. But we will get wrong ftrace_addr for module rec in ftrace_get_addr_new, because rec->flags has not been setup correctly. It can cause the callback function of a ftrace_ops has FTRACE_OPS_FL_SAVE_REGS to be called with pt_regs set to NULL. So setup correct FTRACE_FL_REGS flags for rec when we call referenced_filters to find ftrace_ops references it. Link: https://lkml.kernel.org/r/20200728180554.65203-1-zhouchengming@bytedance.com Cc: stable@vger.kernel.org Fixes: 8c4f3c3fa9681 ("ftrace: Check module functions being traced on reload") Signed-off-by: Chengming Zhou <zhouchengming@bytedance.com> Signed-off-by: Muchun Song <songmuchun@bytedance.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-08-19blktrace: fix debugfs use after freeLuis Chamberlain
[ Upstream commit bad8e64fb19d3a0de5e564d9a7271c31bd684369 ] On commit 6ac93117ab00 ("blktrace: use existing disk debugfs directory") merged on v4.12 Omar fixed the original blktrace code for request-based drivers (multiqueue). This however left in place a possible crash, if you happen to abuse blktrace while racing to remove / add a device. We used to use asynchronous removal of the request_queue, and with that the issue was easier to reproduce. Now that we have reverted to synchronous removal of the request_queue, the issue is still possible to reproduce, its however just a bit more difficult. We essentially run two instances of break-blktrace which add/remove a loop device, and setup a blktrace and just never tear the blktrace down. We do this twice in parallel. This is easily reproduced with the script run_0004.sh from break-blktrace [0]. We can end up with two types of panics each reflecting where we race, one a failed blktrace setup: [ 252.426751] debugfs: Directory 'loop0' with parent 'block' already present! [ 252.432265] BUG: kernel NULL pointer dereference, address: 00000000000000a0 [ 252.436592] #PF: supervisor write access in kernel mode [ 252.439822] #PF: error_code(0x0002) - not-present page [ 252.442967] PGD 0 P4D 0 [ 252.444656] Oops: 0002 [#1] SMP NOPTI [ 252.446972] CPU: 10 PID: 1153 Comm: break-blktrace Tainted: G E 5.7.0-rc2-next-20200420+ #164 [ 252.452673] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 [ 252.456343] RIP: 0010:down_write+0x15/0x40 [ 252.458146] Code: eb ca e8 ae 22 8d ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc 0f 1f 44 00 00 55 48 89 fd e8 52 db ff ff 31 c0 ba 01 00 00 00 <f0> 48 0f b1 55 00 75 0f 48 8b 04 25 c0 8b 01 00 48 89 45 08 5d [ 252.463638] RSP: 0018:ffffa626415abcc8 EFLAGS: 00010246 [ 252.464950] RAX: 0000000000000000 RBX: ffff958c25f0f5c0 RCX: ffffff8100000000 [ 252.466727] RDX: 0000000000000001 RSI: ffffff8100000000 RDI: 00000000000000a0 [ 252.468482] RBP: 00000000000000a0 R08: 0000000000000000 R09: 0000000000000001 [ 252.470014] R10: 0000000000000000 R11: ffff958d1f9227ff R12: 0000000000000000 [ 252.471473] R13: ffff958c25ea5380 R14: ffffffff8cce15f1 R15: 00000000000000a0 [ 252.473346] FS: 00007f2e69dee540(0000) GS:ffff958c2fc80000(0000) knlGS:0000000000000000 [ 252.475225] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 252.476267] CR2: 00000000000000a0 CR3: 0000000427d10004 CR4: 0000000000360ee0 [ 252.477526] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 252.478776] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 252.479866] Call Trace: [ 252.480322] simple_recursive_removal+0x4e/0x2e0 [ 252.481078] ? debugfs_remove+0x60/0x60 [ 252.481725] ? relay_destroy_buf+0x77/0xb0 [ 252.482662] debugfs_remove+0x40/0x60 [ 252.483518] blk_remove_buf_file_callback+0x5/0x10 [ 252.484328] relay_close_buf+0x2e/0x60 [ 252.484930] relay_open+0x1ce/0x2c0 [ 252.485520] do_blk_trace_setup+0x14f/0x2b0 [ 252.486187] __blk_trace_setup+0x54/0xb0 [ 252.486803] blk_trace_ioctl+0x90/0x140 [ 252.487423] ? do_sys_openat2+0x1ab/0x2d0 [ 252.488053] blkdev_ioctl+0x4d/0x260 [ 252.488636] block_ioctl+0x39/0x40 [ 252.489139] ksys_ioctl+0x87/0xc0 [ 252.489675] __x64_sys_ioctl+0x16/0x20 [ 252.490380] do_syscall_64+0x52/0x180 [ 252.491032] entry_SYSCALL_64_after_hwframe+0x44/0xa9 And the other on the device removal: [ 128.528940] debugfs: Directory 'loop0' with parent 'block' already present! [ 128.615325] BUG: kernel NULL pointer dereference, address: 00000000000000a0 [ 128.619537] #PF: supervisor write access in kernel mode [ 128.622700] #PF: error_code(0x0002) - not-present page [ 128.625842] PGD 0 P4D 0 [ 128.627585] Oops: 0002 [#1] SMP NOPTI [ 128.629871] CPU: 12 PID: 544 Comm: break-blktrace Tainted: G E 5.7.0-rc2-next-20200420+ #164 [ 128.635595] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1 04/01/2014 [ 128.640471] RIP: 0010:down_write+0x15/0x40 [ 128.643041] Code: eb ca e8 ae 22 8d ff cc cc cc cc cc cc cc cc cc cc cc cc cc cc 0f 1f 44 00 00 55 48 89 fd e8 52 db ff ff 31 c0 ba 01 00 00 00 <f0> 48 0f b1 55 00 75 0f 65 48 8b 04 25 c0 8b 01 00 48 89 45 08 5d [ 128.650180] RSP: 0018:ffffa9c3c05ebd78 EFLAGS: 00010246 [ 128.651820] RAX: 0000000000000000 RBX: ffff8ae9a6370240 RCX: ffffff8100000000 [ 128.653942] RDX: 0000000000000001 RSI: ffffff8100000000 RDI: 00000000000000a0 [ 128.655720] RBP: 00000000000000a0 R08: 0000000000000002 R09: ffff8ae9afd2d3d0 [ 128.657400] R10: 0000000000000056 R11: 0000000000000000 R12: 0000000000000000 [ 128.659099] R13: 0000000000000000 R14: 0000000000000003 R15: 00000000000000a0 [ 128.660500] FS: 00007febfd995540(0000) GS:ffff8ae9afd00000(0000) knlGS:0000000000000000 [ 128.662204] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 128.663426] CR2: 00000000000000a0 CR3: 0000000420042003 CR4: 0000000000360ee0 [ 128.664776] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [ 128.666022] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 [ 128.667282] Call Trace: [ 128.667801] simple_recursive_removal+0x4e/0x2e0 [ 128.668663] ? debugfs_remove+0x60/0x60 [ 128.669368] debugfs_remove+0x40/0x60 [ 128.669985] blk_trace_free+0xd/0x50 [ 128.670593] __blk_trace_remove+0x27/0x40 [ 128.671274] blk_trace_shutdown+0x30/0x40 [ 128.671935] blk_release_queue+0x95/0xf0 [ 128.672589] kobject_put+0xa5/0x1b0 [ 128.673188] disk_release+0xa2/0xc0 [ 128.673786] device_release+0x28/0x80 [ 128.674376] kobject_put+0xa5/0x1b0 [ 128.674915] loop_remove+0x39/0x50 [loop] [ 128.675511] loop_control_ioctl+0x113/0x130 [loop] [ 128.676199] ksys_ioctl+0x87/0xc0 [ 128.676708] __x64_sys_ioctl+0x16/0x20 [ 128.677274] do_syscall_64+0x52/0x180 [ 128.677823] entry_SYSCALL_64_after_hwframe+0x44/0xa9 The common theme here is: debugfs: Directory 'loop0' with parent 'block' already present This crash happens because of how blktrace uses the debugfs directory where it places its files. Upon init we always create the same directory which would be needed by blktrace but we only do this for make_request drivers (multiqueue) block drivers. When you race a removal of these devices with a blktrace setup you end up in a situation where the make_request recursive debugfs removal will sweep away the blktrace files and then later blktrace will also try to remove individual dentries which are already NULL. The inverse is also possible and hence the two types of use after frees. We don't create the block debugfs directory on init for these types of block devices: * request-based block driver block devices * every possible partition * scsi-generic And so, this race should in theory only be possible with make_request drivers. We can fix the UAF by simply re-using the debugfs directory for make_request drivers (multiqueue) and only creating the ephemeral directory for the other type of block devices. The new clarifications on relying on the q->blk_trace_mutex *and* also checking for q->blk_trace *prior* to processing a blktrace ensures the debugfs directories are only created if no possible directory name clashes are possible. This goes tested with: o nvme partitions o ISCSI with tgt, and blktracing against scsi-generic with: o block o tape o cdrom o media changer o blktests This patch is part of the work which disputes the severity of CVE-2019-19770 which shows this issue is not a core debugfs issue, but a misuse of debugfs within blktace. Fixes: 6ac93117ab00 ("blktrace: use existing disk debugfs directory") Reported-by: syzbot+603294af2d01acfdd6da@syzkaller.appspotmail.com Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Cc: Bart Van Assche <bvanassche@acm.org> Cc: Omar Sandoval <osandov@fb.com> Cc: Hannes Reinecke <hare@suse.com> Cc: Nicolai Stange <nstange@suse.de> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: "Martin K. Petersen" <martin.petersen@oracle.com> Cc: "James E.J. Bottomley" <jejb@linux.ibm.com> Cc: yu kuai <yukuai3@huawei.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-30ring-buffer: Zero out time extend if it is nested and not absoluteSteven Rostedt (VMware)
commit 097350d1c6e1f5808cae142006f18a0bbc57018d upstream. Currently the ring buffer makes events that happen in interrupts that preempt another event have a delta of zero. (Hopefully we can change this soon). But this is to deal with the races of updating a global counter with lockless and nesting functions updating deltas. With the addition of absolute time stamps, the time extend didn't follow this rule. A time extend can happen if two events happen longer than 2^27 nanoseconds appart, as the delta time field in each event is only 27 bits. If that happens, then a time extend is injected with 2^59 bits of nanoseconds to use (18 years). But if the 2^27 nanoseconds happen between two events, and as it is writing the event, an interrupt triggers, it will see the 2^27 difference as well and inject a time extend of its own. But a recent change made the time extend logic not take into account the nesting, and this can cause two time extend deltas to happen moving the time stamp much further ahead than the current time. This gets all reset when the ring buffer moves to the next page, but that can cause time to appear to go backwards. This was observed in a trace-cmd recording, and since the data is saved in a file, with trace-cmd report --debug, it was possible to see that this indeed did happen! bash-52501 110d... 81778.908247: sched_switch: bash:52501 [120] S ==> swapper/110:0 [120] [12770284:0x2e8:64] <idle>-0 110d... 81778.908757: sched_switch: swapper/110:0 [120] R ==> bash:52501 [120] [509947:0x32c:64] TIME EXTEND: delta:306454770 length:0 bash-52501 110.... 81779.215212: sched_swap_numa: src_pid=52501 src_tgid=52388 src_ngid=52501 src_cpu=110 src_nid=2 dst_pid=52509 dst_tgid=52388 dst_ngid=52501 dst_cpu=49 dst_nid=1 [0:0x378:48] TIME EXTEND: delta:306458165 length:0 bash-52501 110dNh. 81779.521670: sched_wakeup: migration/110:565 [0] success=1 CPU:110 [0:0x3b4:40] and at the next page, caused the time to go backwards: bash-52504 110d... 81779.685411: sched_switch: bash:52504 [120] S ==> swapper/110:0 [120] [8347057:0xfb4:64] CPU:110 [SUBBUFFER START] [81779379165886:0x1320000] <idle>-0 110dN.. 81779.379166: sched_wakeup: bash:52504 [120] success=1 CPU:110 [0:0x10:40] <idle>-0 110d... 81779.379167: sched_switch: swapper/110:0 [120] R ==> bash:52504 [120] [1168:0x3c:64] Link: https://lkml.kernel.org/r/20200622151815.345d1bf5@oasis.local.home Cc: Ingo Molnar <mingo@kernel.org> Cc: Andrew Morton <akpm@linux-foundation.org> Cc: Tom Zanussi <zanussi@kernel.org> Cc: stable@vger.kernel.org Fixes: dc4e2801d400b ("ring-buffer: Redefine the unimplemented RINGBUF_TYPE_TIME_STAMP") Reported-by: Julia Lawall <julia.lawall@inria.fr> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-30tracing: Fix event trigger to accept redundant spacesMasami Hiramatsu
commit 6784beada631800f2c5afd567e5628c843362cee upstream. Fix the event trigger to accept redundant spaces in the trigger input. For example, these return -EINVAL echo " traceon" > events/ftrace/print/trigger echo "traceon if common_pid == 0" > events/ftrace/print/trigger echo "disable_event:kmem:kmalloc " > events/ftrace/print/trigger But these are hard to find what is wrong. To fix this issue, use skip_spaces() to remove spaces in front of actual tokens, and set NULL if there is no token. Link: http://lkml.kernel.org/r/159262476352.185015.5261566783045364186.stgit@devnote2 Cc: Tom Zanussi <zanussi@kernel.org> Cc: stable@vger.kernel.org Fixes: 85f2b08268c0 ("tracing: Add basic event trigger framework") Reviewed-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-30blktrace: break out of blktrace setup on concurrent callsLuis Chamberlain
[ Upstream commit 1b0b283648163dae2a214ca28ed5a99f62a77319 ] We use one blktrace per request_queue, that means one per the entire disk. So we cannot run one blktrace on say /dev/vda and then /dev/vda1, or just two calls on /dev/vda. We check for concurrent setup only at the very end of the blktrace setup though. If we try to run two concurrent blktraces on the same block device the second one will fail, and the first one seems to go on. However when one tries to kill the first one one will see things like this: The kernel will show these: ``` debugfs: File 'dropped' in directory 'nvme1n1' already present! debugfs: File 'msg' in directory 'nvme1n1' already present! debugfs: File 'trace0' in directory 'nvme1n1' already present! `` And userspace just sees this error message for the second call: ``` blktrace /dev/nvme1n1 BLKTRACESETUP(2) /dev/nvme1n1 failed: 5/Input/output error ``` The first userspace process #1 will also claim that the files were taken underneath their nose as well. The files are taken away form the first process given that when the second blktrace fails, it will follow up with a BLKTRACESTOP and BLKTRACETEARDOWN. This means that even if go-happy process #1 is waiting for blktrace data, we *have* been asked to take teardown the blktrace. This can easily be reproduced with break-blktrace [0] run_0005.sh test. Just break out early if we know we're already going to fail, this will prevent trying to create the files all over again, which we know still exist. [0] https://github.com/mcgrof/break-blktrace Signed-off-by: Luis Chamberlain <mcgrof@kernel.org> Signed-off-by: Jan Kara <jack@suse.cz> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-24tracing/probe: Fix memleak in fetch_op_data operationsVamshi K Sthambamkadi
commit 3aa8fdc37d16735e8891035becf25b3857d3efe0 upstream. kmemleak report: [<57dcc2ca>] __kmalloc_track_caller+0x139/0x2b0 [<f1c45d0f>] kstrndup+0x37/0x80 [<f9761eb0>] parse_probe_arg.isra.7+0x3cc/0x630 [<055bf2ba>] traceprobe_parse_probe_arg+0x2f5/0x810 [<655a7766>] trace_kprobe_create+0x2ca/0x950 [<4fc6a02a>] create_or_delete_trace_kprobe+0xf/0x30 [<6d1c8a52>] trace_run_command+0x67/0x80 [<be812cc0>] trace_parse_run_command+0xa7/0x140 [<aecfe401>] probes_write+0x10/0x20 [<2027641c>] __vfs_write+0x30/0x1e0 [<6a4aeee1>] vfs_write+0x96/0x1b0 [<3517fb7d>] ksys_write+0x53/0xc0 [<dad91db7>] __ia32_sys_write+0x15/0x20 [<da347f64>] do_syscall_32_irqs_on+0x3d/0x260 [<fd0b7e7d>] do_fast_syscall_32+0x39/0xb0 [<ea5ae810>] entry_SYSENTER_32+0xaf/0x102 Post parse_probe_arg(), the FETCH_OP_DATA operation type is overwritten to FETCH_OP_ST_STRING, as a result memory is never freed since traceprobe_free_probe_arg() iterates only over SYMBOL and DATA op types Setup fetch string operation correctly after fetch_op_data operation. Link: https://lkml.kernel.org/r/20200615143034.GA1734@cosmos Cc: stable@vger.kernel.org Fixes: a42e3c4de964 ("tracing/probe: Add immediate string parameter support") Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-06-24tracing/probe: Fix bpf_task_fd_query() for kprobes and uprobesJean-Philippe Brucker
[ Upstream commit 22d5bd6867364b41576a712755271a7d6161abd6 ] Commit 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe") removed the trace_[ku]probe structure from the trace_event_call->data pointer. As bpf_get_[ku]probe_info() were forgotten in that change, fix them now. These functions are currently only used by the bpf_task_fd_query() syscall handler to collect information about a perf event. Fixes: 60d53e2c3b75 ("tracing/probe: Split trace_event related data from trace_probe") Signed-off-by: Jean-Philippe Brucker <jean-philippe@linaro.org> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Acked-by: Yonghong Song <yhs@fb.com> Acked-by: Masami Hiramatsu <mhiramat@kernel.org> Link: https://lore.kernel.org/bpf/20200608124531.819838-1-jean-philippe@linaro.org Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-24blktrace: fix endianness for blk_log_remap()Chaitanya Kulkarni
[ Upstream commit 5aec598c456fe3c1b71a1202cbb42bdc2a643277 ] The function blk_log_remap() can be simplified by removing the call to get_pdu_remap() that copies the values into extra variable to print the data, which also fixes the endiannness warning reported by sparse. Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-24blktrace: fix endianness in get_pdu_int()Chaitanya Kulkarni
[ Upstream commit 71df3fd82e7cccec7b749a8607a4662d9f7febdd ] In function get_pdu_len() replace variable type from __u64 to __be64. This fixes sparse warning. Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-06-24blktrace: use errno instead of bi_statusChaitanya Kulkarni
[ Upstream commit 48bc3cd3e07a1486f45d9971c75d6090976c3b1b ] In blk_add_trace_spliti() blk_add_trace_bio_remap() use blk_status_to_errno() to pass the error instead of pasing the bi_status. This fixes the sparse warning. Signed-off-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-05-20Stop the ad-hoc games with -Wno-maybe-initializedLinus Torvalds
commit 78a5255ffb6a1af189a83e493d916ba1c54d8c75 upstream. We have some rather random rules about when we accept the "maybe-initialized" warnings, and when we don't. For example, we consider it unreliable for gcc versions < 4.9, but also if -O3 is enabled, or if optimizing for size. And then various kernel config options disabled it, because they know that they trigger that warning by confusing gcc sufficiently (ie PROFILE_ALL_BRANCHES). And now gcc-10 seems to be introducing a lot of those warnings too, so it falls under the same heading as 4.9 did. At the same time, we have a very straightforward way to _enable_ that warning when wanted: use "W=2" to enable more warnings. So stop playing these ad-hoc games, and just disable that warning by default, with the known and straight-forward "if you want to work on the extra compiler warnings, use W=123". Would it be great to have code that is always so obvious that it never confuses the compiler whether a variable is used initialized or not? Yes, it would. In a perfect world, the compilers would be smarter, and our source code would be simpler. That's currently not the world we live in, though. Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-14tracing: Add a vmalloc_sync_mappings() for safe measureSteven Rostedt (VMware)
commit 11f5efc3ab66284f7aaacc926e9351d658e2577b upstream. x86_64 lazily maps in the vmalloc pages, and the way this works with per_cpu areas can be complex, to say the least. Mappings may happen at boot up, and if nothing synchronizes the page tables, those page mappings may not be synced till they are used. This causes issues for anything that might touch one of those mappings in the path of the page fault handler. When one of those unmapped mappings is touched in the page fault handler, it will cause another page fault, which in turn will cause a page fault, and leave us in a loop of page faults. Commit 763802b53a42 ("x86/mm: split vmalloc_sync_all()") split vmalloc_sync_all() into vmalloc_sync_unmappings() and vmalloc_sync_mappings(), as on system exit, it did not need to do a full sync on x86_64 (although it still needed to be done on x86_32). By chance, the vmalloc_sync_all() would synchronize the page mappings done at boot up and prevent the per cpu area from being a problem for tracing in the page fault handler. But when that synchronization in the exit of a task became a nop, it caused the problem to appear. Link: https://lore.kernel.org/r/20200429054857.66e8e333@oasis.local.home Cc: stable@vger.kernel.org Fixes: 737223fbca3b1 ("tracing: Consolidate buffer allocation code") Reported-by: "Tzvetomir Stoyanov (VMware)" <tz.stoyanov@gmail.com> Suggested-by: Joerg Roedel <jroedel@suse.de> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-05-14tracing/kprobes: Fix a double initialization typoMasami Hiramatsu
[ Upstream commit dcbd21c9fca5e954fd4e3d91884907eb6d47187e ] Fix a typo that resulted in an unnecessary double initialization to addr. Link: http://lkml.kernel.org/r/158779374968.6082.2337484008464939919.stgit@devnote2 Cc: Tom Zanussi <zanussi@kernel.org> Cc: Ingo Molnar <mingo@kernel.org> Cc: stable@vger.kernel.org Fixes: c7411a1a126f ("tracing/kprobe: Check whether the non-suffixed symbol is notrace") Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-05-10tracing: Fix memory leaks in trace_events_hist.cVamshi K Sthambamkadi
[ Upstream commit 9da73974eb9c965dd9989befb593b8c8da9e4bdc ] kmemleak report 1: [<9092c50b>] kmem_cache_alloc_trace+0x138/0x270 [<05a2c9ed>] create_field_var+0xcf/0x180 [<528a2d68>] action_create+0xe2/0xc80 [<63f50b61>] event_hist_trigger_func+0x15b5/0x1920 [<28ea5d3d>] trigger_process_regex+0x7b/0xc0 [<3138e86f>] event_trigger_write+0x4d/0xb0 [<ffd66c19>] __vfs_write+0x30/0x200 [<4f424a0d>] vfs_write+0x96/0x1b0 [<da59a290>] ksys_write+0x53/0xc0 [<3717101a>] __ia32_sys_write+0x15/0x20 [<c5f23497>] do_fast_syscall_32+0x70/0x250 [<46e2629c>] entry_SYSENTER_32+0xaf/0x102 This is because save_vars[] of struct hist_trigger_data are not destroyed kmemleak report 2: [<9092c50b>] kmem_cache_alloc_trace+0x138/0x270 [<6e5e97c5>] create_var+0x3c/0x110 [<de82f1b9>] create_field_var+0xaf/0x180 [<528a2d68>] action_create+0xe2/0xc80 [<63f50b61>] event_hist_trigger_func+0x15b5/0x1920 [<28ea5d3d>] trigger_process_regex+0x7b/0xc0 [<3138e86f>] event_trigger_write+0x4d/0xb0 [<ffd66c19>] __vfs_write+0x30/0x200 [<4f424a0d>] vfs_write+0x96/0x1b0 [<da59a290>] ksys_write+0x53/0xc0 [<3717101a>] __ia32_sys_write+0x15/0x20 [<c5f23497>] do_fast_syscall_32+0x70/0x250 [<46e2629c>] entry_SYSENTER_32+0xaf/0x102 struct hist_field allocated through create_var() do not initialize "ref" field to 1. The code in __destroy_hist_field() does not destroy object if "ref" is initialized to zero, the condition if (--hist_field->ref > 1) always passes since unsigned int wraps. kmemleak report 3: [<f8666fcc>] __kmalloc_track_caller+0x139/0x2b0 [<bb7f80a5>] kstrdup+0x27/0x50 [<39d70006>] init_var_ref+0x58/0xd0 [<8ca76370>] create_var_ref+0x89/0xe0 [<f045fc39>] action_create+0x38f/0xc80 [<7c146821>] event_hist_trigger_func+0x15b5/0x1920 [<07de3f61>] trigger_process_regex+0x7b/0xc0 [<e87daf8f>] event_trigger_write+0x4d/0xb0 [<19bf1512>] __vfs_write+0x30/0x200 [<64ce4d27>] vfs_write+0x96/0x1b0 [<a6f34170>] ksys_write+0x53/0xc0 [<7d4230cd>] __ia32_sys_write+0x15/0x20 [<8eadca00>] do_fast_syscall_32+0x70/0x250 [<235cf985>] entry_SYSENTER_32+0xaf/0x102 hist_fields (system & event_name) are not freed Link: http://lkml.kernel.org/r/20200422061503.GA5151@cosmos Signed-off-by: Vamshi K Sthambamkadi <vamshi.k.sthambamkadi@gmail.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-04-21tracing: Fix the race between registering 'snapshot' event trigger and ↵Xiao Yang
triggering 'snapshot' operation commit 0bbe7f719985efd9adb3454679ecef0984cb6800 upstream. Traced event can trigger 'snapshot' operation(i.e. calls snapshot_trigger() or snapshot_count_trigger()) when register_snapshot_trigger() has completed registration but doesn't allocate buffer for 'snapshot' event trigger. In the rare case, 'snapshot' operation always detects the lack of allocated buffer so make register_snapshot_trigger() allocate buffer first. trigger-snapshot.tc in kselftest reproduces the issue on slow vm: ----------------------------------------------------------- cat trace ... ftracetest-3028 [002] .... 236.784290: sched_process_fork: comm=ftracetest pid=3028 child_comm=ftracetest child_pid=3036 <...>-2875 [003] .... 240.460335: tracing_snapshot_instance_cond: *** SNAPSHOT NOT ALLOCATED *** <...>-2875 [003] .... 240.460338: tracing_snapshot_instance_cond: *** stopping trace here! *** ----------------------------------------------------------- Link: http://lkml.kernel.org/r/20200414015145.66236-1-yangx.jy@cn.fujitsu.com Cc: stable@vger.kernel.org Fixes: 93e31ffbf417a ("tracing: Add 'snapshot' event trigger command") Signed-off-by: Xiao Yang <yangx.jy@cn.fujitsu.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-17ftrace/kprobe: Show the maxactive number on kprobe_eventsMasami Hiramatsu
commit 6a13a0d7b4d1171ef9b80ad69abc37e1daa941b3 upstream. Show maxactive parameter on kprobe_events. This allows user to save the current configuration and restore it without losing maxactive parameter. Link: http://lkml.kernel.org/r/4762764a-6df7-bc93-ed60-e336146dce1f@gmail.com Link: http://lkml.kernel.org/r/158503528846.22706.5549974121212526020.stgit@devnote2 Cc: stable@vger.kernel.org Fixes: 696ced4fb1d76 ("tracing/kprobes: expose maxactive for kretprobe in kprobe_events") Reported-by: Taeung Song <treeze.taeung@gmail.com> Signed-off-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-17bpf: Fix deadlock with rq_lock in bpf_send_signal()Yonghong Song
[ Upstream commit 1bc7896e9ef44fd77858b3ef0b8a6840be3a4494 ] When experimenting with bpf_send_signal() helper in our production environment (5.2 based), we experienced a deadlock in NMI mode: #5 [ffffc9002219f770] queued_spin_lock_slowpath at ffffffff8110be24 #6 [ffffc9002219f770] _raw_spin_lock_irqsave at ffffffff81a43012 #7 [ffffc9002219f780] try_to_wake_up at ffffffff810e7ecd #8 [ffffc9002219f7e0] signal_wake_up_state at ffffffff810c7b55 #9 [ffffc9002219f7f0] __send_signal at ffffffff810c8602 #10 [ffffc9002219f830] do_send_sig_info at ffffffff810ca31a #11 [ffffc9002219f868] bpf_send_signal at ffffffff8119d227 #12 [ffffc9002219f988] bpf_overflow_handler at ffffffff811d4140 #13 [ffffc9002219f9e0] __perf_event_overflow at ffffffff811d68cf #14 [ffffc9002219fa10] perf_swevent_overflow at ffffffff811d6a09 #15 [ffffc9002219fa38] ___perf_sw_event at ffffffff811e0f47 #16 [ffffc9002219fc30] __schedule at ffffffff81a3e04d #17 [ffffc9002219fc90] schedule at ffffffff81a3e219 #18 [ffffc9002219fca0] futex_wait_queue_me at ffffffff8113d1b9 #19 [ffffc9002219fcd8] futex_wait at ffffffff8113e529 #20 [ffffc9002219fdf0] do_futex at ffffffff8113ffbc #21 [ffffc9002219fec0] __x64_sys_futex at ffffffff81140d1c #22 [ffffc9002219ff38] do_syscall_64 at ffffffff81002602 #23 [ffffc9002219ff50] entry_SYSCALL_64_after_hwframe at ffffffff81c00068 The above call stack is actually very similar to an issue reported by Commit eac9153f2b58 ("bpf/stackmap: Fix deadlock with rq_lock in bpf_get_stack()") by Song Liu. The only difference is bpf_send_signal() helper instead of bpf_get_stack() helper. The above deadlock is triggered with a perf_sw_event. Similar to Commit eac9153f2b58, the below almost identical reproducer used tracepoint point sched/sched_switch so the issue can be easily caught. /* stress_test.c */ #include <stdio.h> #include <stdlib.h> #include <sys/mman.h> #include <pthread.h> #include <sys/types.h> #include <sys/stat.h> #include <fcntl.h> #define THREAD_COUNT 1000 char *filename; void *worker(void *p) { void *ptr; int fd; char *pptr; fd = open(filename, O_RDONLY); if (fd < 0) return NULL; while (1) { struct timespec ts = {0, 1000 + rand() % 2000}; ptr = mmap(NULL, 4096 * 64, PROT_READ, MAP_PRIVATE, fd, 0); usleep(1); if (ptr == MAP_FAILED) { printf("failed to mmap\n"); break; } munmap(ptr, 4096 * 64); usleep(1); pptr = malloc(1); usleep(1); pptr[0] = 1; usleep(1); free(pptr); usleep(1); nanosleep(&ts, NULL); } close(fd); return NULL; } int main(int argc, char *argv[]) { void *ptr; int i; pthread_t threads[THREAD_COUNT]; if (argc < 2) return 0; filename = argv[1]; for (i = 0; i < THREAD_COUNT; i++) { if (pthread_create(threads + i, NULL, worker, NULL)) { fprintf(stderr, "Error creating thread\n"); return 0; } } for (i = 0; i < THREAD_COUNT; i++) pthread_join(threads[i], NULL); return 0; } and the following command: 1. run `stress_test /bin/ls` in one windown 2. hack bcc trace.py with the following change: # --- a/tools/trace.py # +++ b/tools/trace.py @@ -513,6 +513,7 @@ BPF_PERF_OUTPUT(%s); __data.tgid = __tgid; __data.pid = __pid; bpf_get_current_comm(&__data.comm, sizeof(__data.comm)); + bpf_send_signal(10); %s %s %s.perf_submit(%s, &__data, sizeof(__data)); 3. in a different window run ./trace.py -p $(pidof stress_test) t:sched:sched_switch The deadlock can be reproduced in our production system. Similar to Song's fix, the fix is to delay sending signal if irqs is disabled to avoid deadlocks involving with rq_lock. With this change, my above stress-test in our production system won't cause deadlock any more. I also implemented a scale-down version of reproducer in the selftest (a subsequent commit). With latest bpf-next, it complains for the following potential deadlock. [ 32.832450] -> #1 (&p->pi_lock){-.-.}: [ 32.833100] _raw_spin_lock_irqsave+0x44/0x80 [ 32.833696] task_rq_lock+0x2c/0xa0 [ 32.834182] task_sched_runtime+0x59/0xd0 [ 32.834721] thread_group_cputime+0x250/0x270 [ 32.835304] thread_group_cputime_adjusted+0x2e/0x70 [ 32.835959] do_task_stat+0x8a7/0xb80 [ 32.836461] proc_single_show+0x51/0xb0 ... [ 32.839512] -> #0 (&(&sighand->siglock)->rlock){....}: [ 32.840275] __lock_acquire+0x1358/0x1a20 [ 32.840826] lock_acquire+0xc7/0x1d0 [ 32.841309] _raw_spin_lock_irqsave+0x44/0x80 [ 32.841916] __lock_task_sighand+0x79/0x160 [ 32.842465] do_send_sig_info+0x35/0x90 [ 32.842977] bpf_send_signal+0xa/0x10 [ 32.843464] bpf_prog_bc13ed9e4d3163e3_send_signal_tp_sched+0x465/0x1000 [ 32.844301] trace_call_bpf+0x115/0x270 [ 32.844809] perf_trace_run_bpf_submit+0x4a/0xc0 [ 32.845411] perf_trace_sched_switch+0x10f/0x180 [ 32.846014] __schedule+0x45d/0x880 [ 32.846483] schedule+0x5f/0xd0 ... [ 32.853148] Chain exists of: [ 32.853148] &(&sighand->siglock)->rlock --> &p->pi_lock --> &rq->lock [ 32.853148] [ 32.854451] Possible unsafe locking scenario: [ 32.854451] [ 32.855173] CPU0 CPU1 [ 32.855745] ---- ---- [ 32.856278] lock(&rq->lock); [ 32.856671] lock(&p->pi_lock); [ 32.857332] lock(&rq->lock); [ 32.857999] lock(&(&sighand->siglock)->rlock); Deadlock happens on CPU0 when it tries to acquire &sighand->siglock but it has been held by CPU1 and CPU1 tries to grab &rq->lock and cannot get it. This is not exactly the callstack in our production environment, but sympotom is similar and both locks are using spin_lock_irqsave() to acquire the lock, and both involves rq_lock. The fix to delay sending signal when irq is disabled also fixed this issue. Signed-off-by: Yonghong Song <yhs@fb.com> Signed-off-by: Alexei Starovoitov <ast@kernel.org> Cc: Song Liu <songliubraving@fb.com> Link: https://lore.kernel.org/bpf/20200304191104.2796501-1-yhs@fb.com Signed-off-by: Sasha Levin <sashal@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-21tracing: Fix number printing bug in print_synth_event()Tom Zanussi
[ Upstream commit 784bd0847eda032ed2f3522f87250655a18c0190 ] Fix a varargs-related bug in print_synth_event() which resulted in strange output and oopses on 32-bit x86 systems. The problem is that trace_seq_printf() expects the varargs to match the format string, but print_synth_event() was always passing u64 values regardless. This results in unspecified behavior when unpacking with va_arg() in trace_seq_printf(). Add a function that takes the size into account when calling trace_seq_printf(). Before: modprobe-1731 [003] .... 919.039758: gen_synth_test: next_pid_field=777(null)next_comm_field=hula hoops ts_ns=1000000 ts_ms=1000 cpu=3(null)my_string_field=thneed my_int_field=598(null) After: insmod-1136 [001] .... 36.634590: gen_synth_test: next_pid_field=777 next_comm_field=hula hoops ts_ns=1000000 ts_ms=1000 cpu=1 my_string_field=thneed my_int_field=598 Link: http://lkml.kernel.org/r/a9b59eb515dbbd7d4abe53b347dccf7a8e285657.1581720155.git.zanussi@kernel.org Reported-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-12blktrace: fix dereference after null checkCengiz Can
[ Upstream commit 153031a301bb07194e9c37466cfce8eacb977621 ] There was a recent change in blktrace.c that added a RCU protection to `q->blk_trace` in order to fix a use-after-free issue during access. However the change missed an edge case that can lead to dereferencing of `bt` pointer even when it's NULL: Coverity static analyzer marked this as a FORWARD_NULL issue with CID 1460458. ``` /kernel/trace/blktrace.c: 1904 in sysfs_blk_trace_attr_store() 1898 ret = 0; 1899 if (bt == NULL) 1900 ret = blk_trace_setup_queue(q, bdev); 1901 1902 if (ret == 0) { 1903 if (attr == &dev_attr_act_mask) >>> CID 1460458: Null pointer dereferences (FORWARD_NULL) >>> Dereferencing null pointer "bt". 1904 bt->act_mask = value; 1905 else if (attr == &dev_attr_pid) 1906 bt->pid = value; 1907 else if (attr == &dev_attr_start_lba) 1908 bt->start_lba = value; 1909 else if (attr == &dev_attr_end_lba) ``` Added a reassignment with RCU annotation to fix the issue. Fixes: c780e86dd48 ("blktrace: Protect q->blk_trace with RCU") Cc: stable@vger.kernel.org Reviewed-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bob Liu <bob.liu@oracle.com> Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Cengiz Can <cengiz@kernel.wtf> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-05blktrace: Protect q->blk_trace with RCUJan Kara
[ Upstream commit c780e86dd48ef6467a1146cf7d0fe1e05a635039 ] KASAN is reporting that __blk_add_trace() has a use-after-free issue when accessing q->blk_trace. Indeed the switching of block tracing (and thus eventual freeing of q->blk_trace) is completely unsynchronized with the currently running tracing and thus it can happen that the blk_trace structure is being freed just while __blk_add_trace() works on it. Protect accesses to q->blk_trace by RCU during tracing and make sure we wait for the end of RCU grace period when shutting down tracing. Luckily that is rare enough event that we can afford that. Note that postponing the freeing of blk_trace to an RCU callback should better be avoided as it could have unexpected user visible side-effects as debugfs files would be still existing for a short while block tracing has been shut down. Link: https://bugzilla.kernel.org/show_bug.cgi?id=205711 CC: stable@vger.kernel.org Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com> Reviewed-by: Ming Lei <ming.lei@redhat.com> Tested-by: Ming Lei <ming.lei@redhat.com> Reviewed-by: Bart Van Assche <bvanassche@acm.org> Reported-by: Tristan Madani <tristmd@gmail.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-03-05tracing: Disable trace_printk() on post poned testsSteven Rostedt (VMware)
commit 78041c0c9e935d9ce4086feeff6c569ed88ddfd4 upstream. The tracing seftests checks various aspects of the tracing infrastructure, and one is filtering. If trace_printk() is active during a self test, it can cause the filtering to fail, which will disable that part of the trace. To keep the selftests from failing because of trace_printk() calls, trace_printk() checks the variable tracing_selftest_running, and if set, it does not write to the tracing buffer. As some tracers were registered earlier in boot, the selftest they triggered would fail because not all the infrastructure was set up for the full selftest. Thus, some of the tests were post poned to when their infrastructure was ready (namely file system code). The postpone code did not set the tracing_seftest_running variable, and could fail if a trace_printk() was added and executed during their run. Cc: stable@vger.kernel.org Fixes: 9afecfbb95198 ("tracing: Postpone tracer start-up tests till the system is more robust") Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-24trigger_next should increase position indexVasily Averin
[ Upstream commit 6722b23e7a2ace078344064a9735fb73e554e9ef ] if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Without patch: # dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist # Available triggers: # traceon traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist 6+1 records in 6+1 records out 206 bytes copied, 0.00027916 s, 738 kB/s Notice the printing of "# Available triggers:..." after the line. With the patch: # dd bs=30 skip=1 if=/sys/kernel/tracing/events/sched/sched_switch/trigger dd: /sys/kernel/tracing/events/sched/sched_switch/trigger: cannot skip to specified offset n traceoff snapshot stacktrace enable_event disable_event enable_hist disable_hist hist 2+1 records in 2+1 records out 88 bytes copied, 0.000526867 s, 167 kB/s It only prints the end of the file, and does not restart. Link: http://lkml.kernel.org/r/3c35ee24-dd3a-8119-9c19-552ed253388a@virtuozzo.com https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-02-24ftrace: fpid_next() should increase position indexVasily Averin
[ Upstream commit e4075e8bdffd93a9b6d6e1d52fabedceeca5a91b ] if seq_file .next fuction does not change position index, read after some lseek can generate unexpected output. Without patch: # dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset id no pid 2+1 records in 2+1 records out 10 bytes copied, 0.000213285 s, 46.9 kB/s Notice the "id" followed by "no pid". With the patch: # dd bs=4 skip=1 if=/sys/kernel/tracing/set_ftrace_pid dd: /sys/kernel/tracing/set_ftrace_pid: cannot skip to specified offset id 0+1 records in 0+1 records out 3 bytes copied, 0.000202112 s, 14.8 kB/s Notice that it only prints "id" and not the "no pid" afterward. Link: http://lkml.kernel.org/r/4f87c6ad-f114-30bb-8506-c32274ce2992@virtuozzo.com https://bugzilla.kernel.org/show_bug.cgi?id=206283 Signed-off-by: Vasily Averin <vvs@virtuozzo.com> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-02-24tracing: Simplify assignment parsing for hist triggersTom Zanussi
[ Upstream commit b527b638fd63ba791dc90a0a6e9a3035b10df52b ] In the process of adding better error messages for sorting, I realized that strsep was being used incorrectly and some of the error paths I was expecting to be hit weren't and just fell through to the common invalid key error case. It also became obvious that for keyword assignments, it wasn't necessary to save the full assignment and reparse it later, and having a common empty-assignment check would also make more sense in terms of error processing. Change the code to fix these problems and simplify it for new error message changes in a subsequent patch. Link: http://lkml.kernel.org/r/1c3ef0b6655deaf345f6faee2584a0298ac2d743.1561743018.git.zanussi@kernel.org Fixes: e62347d24534 ("tracing: Add hist trigger support for user-defined sorting ('sort=' param)") Fixes: 7ef224d1d0e3 ("tracing: Add 'hist' event trigger command") Fixes: a4072fe85ba3 ("tracing: Add a clock attribute for hist triggers") Reported-by: Masami Hiramatsu <mhiramat@kernel.org> Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org> Signed-off-by: Tom Zanussi <zanussi@kernel.org> Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org> Signed-off-by: Sasha Levin <sashal@kernel.org>