linux-stable.git/drivers/tty/sysrq.c, branch linux-5.15.y

tty/sysrq: replace smp_processor_id() with get_cpu()

2023-11-28T16:56:27+00:00

commit dd976a97d15b47656991e185a94ef42a0fa5cfd4 upstream.

The smp_processor_id() shouldn't be called from preemptible code.
Instead use get_cpu() and put_cpu() which disables preemption in
addition to getting the processor id. Enable preemption back after
calling schedule_work() to make sure that the work gets scheduled on all
cores other than the current core. We want to avoid a scenario where
current core's stack trace is printed multiple times and one core's
stack trace isn't printed because of scheduling of current task.

This fixes the following bug:

[  119.143590] sysrq: Show backtrace of all active CPUs
[  119.143902] BUG: using smp_processor_id() in preemptible [00000000] code: bash/873
[  119.144586] caller is debug_smp_processor_id+0x20/0x30
[  119.144827] CPU: 6 PID: 873 Comm: bash Not tainted 5.10.124-dirty #3
[  119.144861] Hardware name: QEMU QEMU Virtual Machine, BIOS 2023.05-1 07/22/2023
[  119.145053] Call trace:
[  119.145093]  dump_backtrace+0x0/0x1a0
[  119.145122]  show_stack+0x18/0x70
[  119.145141]  dump_stack+0xc4/0x11c
[  119.145159]  check_preemption_disabled+0x100/0x110
[  119.145175]  debug_smp_processor_id+0x20/0x30
[  119.145195]  sysrq_handle_showallcpus+0x20/0xc0
[  119.145211]  __handle_sysrq+0x8c/0x1a0
[  119.145227]  write_sysrq_trigger+0x94/0x12c
[  119.145247]  proc_reg_write+0xa8/0xe4
[  119.145266]  vfs_write+0xec/0x280
[  119.145282]  ksys_write+0x6c/0x100
[  119.145298]  __arm64_sys_write+0x20/0x30
[  119.145315]  el0_svc_common.constprop.0+0x78/0x1e4
[  119.145332]  do_el0_svc+0x24/0x8c
[  119.145348]  el0_svc+0x10/0x20
[  119.145364]  el0_sync_handler+0x134/0x140
[  119.145381]  el0_sync+0x180/0x1c0

Cc: jirislaby@kernel.org
Cc: stable@vger.kernel.org
Fixes: 47cab6a722d4 ("debug lockups: Improve lockup detection, fix generic arch fallback")
Signed-off-by: Muhammad Usama Anjum 
Link: https://lore.kernel.org/r/20231009162021.3607632-1-usama.anjum@collabora.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Greg Kroah-Hartman

workqueue: Introduce show_one_worker_pool and show_one_workqueue.

2023-05-11T14:00:35+00:00

[ Upstream commit 55df0933be74bd2e52aba0b67eb743ae0feabe7e ]

Currently show_workqueue_state shows the state of all workqueues and of
all worker pools. In certain cases we may need to dump state of only a
specific workqueue or worker pool. For example in destroy_workqueue we
only need to show state of the workqueue which is getting destroyed.

So rename show_workqueue_state to show_all_workqueues(to signify it
dumps state of all busy workqueues) and divide it into more granular
functions (show_one_workqueue and show_one_worker_pool), that would show
states of individual workqueues and worker pools and can be used in
cases such as the one mentioned above.

Also, as mentioned earlier, make destroy_workqueue dump data pertaining
to only the workqueue that is being destroyed and make user(s) of
earlier interface(show_workqueue_state), use new interface
(show_all_workqueues).

Signed-off-by: Imran Khan 
Signed-off-by: Tejun Heo 
Stable-dep-of: 335a42ebb0ca ("workqueue: Fix hung time report of worker pools")
Signed-off-by: Sasha Levin

sysrq: do not omit current cpu when showing backtrace of all active CPUs

2022-06-14T16:36:21+00:00

[ Upstream commit 5390e7f46b9d5546d45a83e6463bc656678b1d0e ]

The backtrace of current CPU also should be printed as it is active. This
change add stack trace for current CPU and print a hint for idle CPU for
the generic workqueue based printing. (x86 already does this)

Now it looks like below:
[  279.401567] sysrq: Show backtrace of all active CPUs
[  279.407234] sysrq: CPU5:
[  279.407505] Call Trace:
[  279.408789] [] dump_backtrace+0x2c/0x3a
[  279.411698] [] show_stack+0x32/0x3e
[  279.411809] [] sysrq_handle_showallcpus+0x4c/0xc6
[  279.411929] [] __handle_sysrq+0x106/0x26c
[  279.412034] [] write_sysrq_trigger+0x64/0x74
[  279.412139] [] proc_reg_write+0x8e/0xe2
[  279.412252] [] vfs_write+0x90/0x2be
[  279.412362] [] ksys_write+0xa6/0xce
[  279.412467] [] sys_write+0x2a/0x38
[  279.412689] [] ret_from_syscall+0x0/0x2
[  279.417173] sysrq: CPU6: backtrace skipped as idling
[  279.417185] sysrq: CPU4: backtrace skipped as idling
[  279.417187] sysrq: CPU0: backtrace skipped as idling
[  279.417181] sysrq: CPU7: backtrace skipped as idling
[  279.417190] sysrq: CPU1: backtrace skipped as idling
[  279.417193] sysrq: CPU3: backtrace skipped as idling
[  279.417219] sysrq: CPU2:
[  279.419179] Call Trace:
[  279.419440] [] dump_backtrace+0x2c/0x3a
[  279.419782] [] show_stack+0x32/0x3e
[  279.420015] [] showacpu+0x5c/0x96
[  279.420317] [] flush_smp_call_function_queue+0xd6/0x218
[  279.420569] [] generic_smp_call_function_single_interrupt+0x14/0x1c
[  279.420798] [] handle_IPI+0xaa/0x13a
[  279.421024] [] riscv_intc_irq+0x56/0x70
[  279.421274] [] generic_handle_arch_irq+0x6a/0xfa
[  279.421518] [] ret_from_exception+0x0/0x10
[  279.421750] [] rcu_idle_enter+0x16/0x1e

Signed-off-by: Changbin Du 
Link: https://lore.kernel.org/r/20220117154300.2808-1-changbin.du@gmail.com
Signed-off-by: Greg Kroah-Hartman 
Signed-off-by: Sasha Levin

tty: replace in_irq() with in_hardirq()

2021-08-16T17:01:52+00:00

Replace the obsolete and ambiguos macro in_irq() with new
macro in_hardirq().

Reviewed-by: Jiri Slaby 
Signed-off-by: Changbin Du 
Link: https://lore.kernel.org/r/20210814005033.2381-1-changbin.du@gmail.com
Signed-off-by: Greg Kroah-Hartman

tty/sysrq: Fix issues of code indent should use tabs

2021-04-10T08:33:00+00:00

Fix issues of code indent should use tabs, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1617779210-51576-3-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty/sysrq: Add a blank line after declarations

2021-04-10T08:33:00+00:00

Add a blank line after declarations, reported by checkpatch.pl.

Signed-off-by: Xiaofei Tan 
Link: https://lore.kernel.org/r/1617779210-51576-2-git-send-email-tanxiaofei@huawei.com
Signed-off-by: Greg Kroah-Hartman

tty/sysrq: Extend the sysrq_key_table to cover capital letters

2020-10-02T12:56:06+00:00

All slots in sysrq_key_table[] are either used, reserved or at least
commented with their intended use. This patch adds capital letter versions
available, which means adding 26 more entries.

For already existing SysRq operations the user presses Alt-SysRq-, and
for the newly added ones Alt-Shift-SysRq-.

Signed-off-by: Andrzej Pietrasiewicz 
Acked-by: Daniel Vetter 
Link: https://lore.kernel.org/r/20200818112825.6445-2-andrzej.p@collabora.com
Signed-off-by: Greg Kroah-Hartman

tty/sysrq: emergency_thaw_all does not depend on CONFIG_BLOCK

2020-06-24T15:16:02+00:00

We can also thaw non-block file systems.  Remove the CONFIG_BLOCK in
sysrq.c after making the prototype available unconditionally.

Signed-off-by: Christoph Hellwig 
Reviewed-by: Bart Van Assche 
Reviewed-by: Greg Kroah-Hartman 
Signed-off-by: Jens Axboe

kernel: rename show_stack_loglvl() => show_stack()

2020-06-09T16:39:13+00:00

Now the last users of show_stack() got converted to use an explicit log
level, show_stack_loglvl() can drop it's redundant suffix and become once
again well known show_stack().

Signed-off-by: Dmitry Safonov 
Signed-off-by: Andrew Morton 
Link: http://lkml.kernel.org/r/20200418201944.482088-51-dima@arista.com
Signed-off-by: Linus Torvalds

sysrq: use show_stack_loglvl()

2020-06-09T16:39:12+00:00

Show the stack trace on a CPU with the same log level as "CPU%d" header.

Signed-off-by: Dmitry Safonov 
Signed-off-by: Andrew Morton 
Cc: Greg Kroah-Hartman 
Cc: Jiri Slaby 
Link: http://lkml.kernel.org/r/20200418201944.482088-45-dima@arista.com
Signed-off-by: Linus Torvalds