linux-stable.git/kernel, branch v3.0.7

ftrace: Fix regression where ftrace breaks when modules are loaded

2011-10-16T21:14:55+00:00

commit f7bc8b61f65726ff98f52e286b28e294499d7a08 upstream.

Enabling function tracer to trace all functions, then load a module and
then disable function tracing will cause ftrace to fail.

This can also happen by enabling function tracing on the command line:

  ftrace=function

and during boot up, modules are loaded, then you disable function tracing
with 'echo nop > current_tracer' you will trigger a bug in ftrace that
will shut itself down.

The reason is, the new ftrace code keeps ref counts of all ftrace_ops that
are registered for tracing. When one or more ftrace_ops are registered,
all the records that represent the functions that the ftrace_ops will
trace have a ref count incremented. If this ref count is not zero,
when the code modification runs, that function will be enabled for tracing.
If the ref count is zero, that function will be disabled from tracing.

To make sure the accounting was working, FTRACE_WARN_ON()s were added
to updating of the ref counts.

If the ref count hits its max (> 2^30 ftrace_ops added), or if
the ref count goes below zero, a FTRACE_WARN_ON() is triggered which
disables all modification of code.

Since it is common for ftrace_ops to trace all functions in the kernel,
instead of creating > 20,000 hash items for the ftrace_ops, the hash
count is just set to zero, and it represents that the ftrace_ops is
to trace all functions. This is where the issues arrise.

If you enable function tracing to trace all functions, and then add
a module, the modules function records do not get the ref count updated.
When the function tracer is disabled, all function records ref counts
are subtracted. Since the modules never had their ref counts incremented,
they go below zero and the FTRACE_WARN_ON() is triggered.

The solution to this is rather simple. When modules are loaded, and
their functions are added to the the ftrace pool, look to see if any
ftrace_ops are registered that trace all functions. And for those,
update the ref count for the module function records.

Reported-by: Thomas Gleixner 
Signed-off-by: Steven Rostedt

ftrace: Fix regression of :mod:module function enabling

2011-10-16T21:14:55+00:00

commit 43dd61c9a09bd413e837df829e6bfb42159be52a upstream.

The new code that allows different utilities to pick and choose
what functions they trace broke the :mod: hook that allows users
to trace only functions of a particular module.

The reason is that the :mod: hook bypasses the hash that is setup
to allow individual users to trace their own functions and uses
the global hash directly. But if the global hash has not been
set up, it will cause a bug:

echo '*:mod:radeon' > /sys/kernel/debug/set_ftrace_filter

produces:

 [drm:drm_mode_getfb] *ERROR* invalid framebuffer id
 [drm:radeon_crtc_page_flip] *ERROR* failed to reserve new rbo buffer before flip
 BUG: unable to handle kernel paging request at ffffffff8160ec90
 IP: [] add_hash_entry+0x66/0xd0
 PGD 1a05067 PUD 1a09063 PMD 80000000016001e1
 Oops: 0003 [#1] SMP Jul  7 04:02:28 phyllis kernel: [55303.858604] CPU 1
 Modules linked in: cryptd aes_x86_64 aes_generic binfmt_misc rfcomm bnep ip6table_filter hid radeon r8169 ahci libahci mii ttm drm_kms_helper drm video i2c_algo_bit intel_agp intel_gtt

 Pid: 10344, comm: bash Tainted: G        WC  3.0.0-rc5 #1 Dell Inc. Inspiron N5010/0YXXJJ
 RIP: 0010:[]  [] add_hash_entry+0x66/0xd0
 RSP: 0018:ffff88003a96bda8  EFLAGS: 00010246
 RAX: ffff8801301735c0 RBX: ffffffff8160ec80 RCX: 0000000000306ee0
 RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff880137c92940
 RBP: ffff88003a96bdb8 R08: ffff880137c95680 R09: 0000000000000000
 R10: 0000000000000001 R11: 0000000000000000 R12: ffffffff81c9df78
 R13: ffff8801153d1000 R14: 0000000000000000 R15: 0000000000000000
 FS: 00007f329c18a700(0000) GS:ffff880137c80000(0000) knlGS:0000000000000000
 CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
 CR2: ffffffff8160ec90 CR3: 000000003002b000 CR4: 00000000000006e0
 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
 DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400
 Process bash (pid: 10344, threadinfo ffff88003a96a000, task ffff88012fcfc470)
 Stack:
  0000000000000fd0 00000000000000fc ffff88003a96be38 ffffffff810d92f5
  ffff88011c4c4e00 ffff880000000000 000000000b69f4d0 ffffffff8160ec80
  ffff8800300e6f06 0000000081130295 0000000000000282 ffff8800300e6f00
 Call Trace:
  [] match_records+0x155/0x1b0
  [] ftrace_mod_callback+0xbc/0x100
  [] ftrace_regex_write+0x16f/0x210
  [] ftrace_filter_write+0xf/0x20
  [] vfs_write+0xc8/0x190
  [] sys_write+0x51/0x90
  [] system_call_fastpath+0x16/0x1b
 Code: 48 8b 33 31 d2 48 85 f6 75 33 49 89 d4 4c 03 63 08 49 8b 14 24 48 85 d2 48 89 10 74 04 48 89 42 08 49 89 04 24 4c 89 60 08 31 d2
 RIP [] add_hash_entry+0x66/0xd0
  RSP 
 CR2: ffffffff8160ec90
 ---[ end trace a5d031828efdd88e ]---

Reported-by: Brian Marete 
Signed-off-by: Steven Rostedt 
Signed-off-by: Greg Kroah-Hartman

posix-cpu-timers: Cure SMP wobbles

2011-10-16T21:14:51+00:00

commit d670ec13178d0fd8680e6742a2bc6e04f28f87d8 upstream.

David reported:

  Attached below is a watered-down version of rt/tst-cpuclock2.c from
  GLIBC.  Just build it with "gcc -o test test.c -lpthread -lrt" or
  similar.

  Run it several times, and you will see cases where the main thread
  will measure a process clock difference before and after the nanosleep
  which is smaller than the cpu-burner thread's individual thread clock
  difference.  This doesn't make any sense since the cpu-burner thread
  is part of the top-level process's thread group.

  I've reproduced this on both x86-64 and sparc64 (using both 32-bit and
  64-bit binaries).

  For example:

  [davem@boricha build-x86_64-linux]$ ./test
  process: before(0.001221967) after(0.498624371) diff(497402404)
  thread:  before(0.000081692) after(0.498316431) diff(498234739)
  self:    before(0.001223521) after(0.001240219) diff(16698)
  [davem@boricha build-x86_64-linux]$

  The diff of 'process' should always be >= the diff of 'thread'.

  I make sure to wrap the 'thread' clock measurements the most tightly
  around the nanosleep() call, and that the 'process' clock measurements
  are the outer-most ones.

  ---
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 
  #include 

  static pthread_barrier_t barrier;

  static void *chew_cpu(void *arg)
  {
	  pthread_barrier_wait(&barrier);
	  while (1)
		  __asm__ __volatile__("" : : : "memory");
	  return NULL;
  }

  int main(void)
  {
	  clockid_t process_clock, my_thread_clock, th_clock;
	  struct timespec process_before, process_after;
	  struct timespec me_before, me_after;
	  struct timespec th_before, th_after;
	  struct timespec sleeptime;
	  unsigned long diff;
	  pthread_t th;
	  int err;

	  err = clock_getcpuclockid(0, &process_clock);
	  if (err)
		  return 1;

	  err = pthread_getcpuclockid(pthread_self(), &my_thread_clock);
	  if (err)
		  return 1;

	  pthread_barrier_init(&barrier, NULL, 2);
	  err = pthread_create(&th, NULL, chew_cpu, NULL);
	  if (err)
		  return 1;

	  err = pthread_getcpuclockid(th, &th_clock);
	  if (err)
		  return 1;

	  pthread_barrier_wait(&barrier);

	  err = clock_gettime(process_clock, &process_before);
	  if (err)
		  return 1;

	  err = clock_gettime(my_thread_clock, &me_before);
	  if (err)
		  return 1;

	  err = clock_gettime(th_clock, &th_before);
	  if (err)
		  return 1;

	  sleeptime.tv_sec = 0;
	  sleeptime.tv_nsec = 500000000;
	  nanosleep(&sleeptime, NULL);

	  err = clock_gettime(th_clock, &th_after);
	  if (err)
		  return 1;

	  err = clock_gettime(my_thread_clock, &me_after);
	  if (err)
		  return 1;

	  err = clock_gettime(process_clock, &process_after);
	  if (err)
		  return 1;

	  diff = process_after.tv_nsec - process_before.tv_nsec;
	  printf("process: before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n",
		 process_before.tv_sec, process_before.tv_nsec,
		 process_after.tv_sec, process_after.tv_nsec, diff);
	  diff = th_after.tv_nsec - th_before.tv_nsec;
	  printf("thread:  before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n",
		 th_before.tv_sec, th_before.tv_nsec,
		 th_after.tv_sec, th_after.tv_nsec, diff);
	  diff = me_after.tv_nsec - me_before.tv_nsec;
	  printf("self:    before(%lu.%.9lu) after(%lu.%.9lu) diff(%lu)\n",
		 me_before.tv_sec, me_before.tv_nsec,
		 me_after.tv_sec, me_after.tv_nsec, diff);

	  return 0;
  }

This is due to us using p->se.sum_exec_runtime in
thread_group_cputime() where we iterate the thread group and sum all
data. This does not take time since the last schedule operation (tick
or otherwise) into account. We can cure this by using
task_sched_runtime() at the cost of having to take locks.

This also means we can (and must) do away with
thread_group_sched_runtime() since the modified thread_group_cputime()
is now more accurate and would deadlock when called from
thread_group_sched_runtime().

Aside of that it makes the function safe on 32 bit systems. The old
code added t->se.sum_exec_runtime unprotected. sum_exec_runtime is a
64bit value and could be changed on another cpu at the same time.

Reported-by: David Miller 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1314874459.7945.22.camel@twins
Tested-by: David Miller 
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

sched: Fix up wchan borkage

2011-10-16T21:14:51+00:00

commit 6ebbe7a07b3bc40b168d2afc569a6543c020d2e3 upstream.

Commit c259e01a1ec ("sched: Separate the scheduler entry for
preemption") contained a boo-boo wrecking wchan output. It forgot to
put the new schedule() function in the __sched section and thereby
doesn't get properly ignored for things like wchan.

Tested-by: Simon Kirby 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20110923000346.GA25425@hostway.ca
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched/rt: Migrate equal priority tasks to available CPUs

2011-10-16T21:14:51+00:00

commit 3be209a8e22cedafc1b6945608b7bb8d9887ab61 upstream.

Commit 43fa5460fe60dea5c610490a1d263415419c60f6 ("sched: Try not to
migrate higher priority RT tasks") also introduced a change in behavior
which keeps RT tasks on the same CPU if there is an equal priority RT
task currently running even if there are empty CPUs available.

This can cause unnecessary wakeup latencies, and can prevent the
scheduler from balancing all RT tasks across available CPUs.

This change causes an RT task to search for a new CPU if an equal
priority RT task is already running on wakeup.  Lower priority tasks
will still have to wait on higher priority tasks, but the system should
still balance out because there is always the possibility that if there
are both a high and low priority RT tasks on a given CPU that the high
priority task could wakeup while the low priority task is running and
force it to search for a better runqueue.

Signed-off-by: Shawn Bohrer 
Acked-by: Steven Rostedt 
Tested-by: Steven Rostedt 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1315837684-18733-1-git-send-email-sbohrer@rgmadvisors.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

workqueue: lock cwq access in drain_workqueue

2011-10-03T18:40:31+00:00

commit fa2563e41c3d6d6e8af437643981ed28ae0cb56d upstream.

Take cwq->gcwq->lock to avoid racing between drain_workqueue checking to
make sure the workqueues are empty and cwq_dec_nr_in_flight decrementing
and then incrementing nr_active when it activates a delayed work.

We discovered this when a corner case in one of our drivers resulted in
us trying to destroy a workqueue in which the remaining work would
always requeue itself again in the same workqueue.  We would hit this
race condition and trip the BUG_ON on workqueue.c:3080.

Signed-off-by: Thomas Tuttle 
Acked-by: Tejun Heo 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds 
Signed-off-by: Greg Kroah-Hartman

genirq: Make irq_shutdown() symmetric vs. irq_startup again

2011-10-03T18:40:27+00:00

commit ed585a651681e822089087b426e6ebfb6d3d9873 upstream.

If an irq_chip provides .irq_shutdown(), but neither of .irq_disable() or
.irq_mask(), free_irq() crashes when jumping to NULL.
Fix this by only trying .irq_disable() and .irq_mask() if there's no
.irq_shutdown() provided.

This revives the symmetry with irq_startup(), which tries .irq_startup(),
.irq_enable(), and irq_unmask(), and makes it consistent with the comment for
irq_chip.irq_shutdown() in , which says:

 * @irq_shutdown:	shut down the interrupt (defaults to ->disable if NULL)

This is also how __free_irq() behaved before the big overhaul, cfr. e.g.
3b56f0585fd4c02d047dc406668cb40159b2d340 ("genirq: Remove bogus conditional"),
where the core interrupt code always overrode .irq_shutdown() to
.irq_disable() if .irq_shutdown() was NULL.

Signed-off-by: Geert Uytterhoeven 
Cc: linux-m68k@lists.linux-m68k.org
Link: http://lkml.kernel.org/r/1315742394-16036-2-git-send-email-geert@linux-m68k.org
Signed-off-by: Thomas Gleixner 
Signed-off-by: Greg Kroah-Hartman

sched: Fix a memory leak in __sdt_free()

2011-10-03T18:40:09+00:00

commit feff8fa0075bdfd43c841e9d689ed81adda988d6 upstream.

This patch fixes the following memory leak:

unreferenced object 0xffff880107266800 (size 512):
  comm "sched-powersave", pid 3718, jiffies 4323097853 (age 27495.450s)
  hex dump (first 32 bytes):
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
    00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00  ................
  backtrace:
    [] create_object+0x187/0x28b
    [] kmemleak_alloc+0x73/0x98
    [] __kmalloc_node+0x104/0x159
    [] kzalloc_node.clone.97+0x15/0x17
    [] build_sched_domains+0xb7/0x7f3
    [] partition_sched_domains+0x1db/0x24a
    [] do_rebuild_sched_domains+0x3b/0x47
    [] rebuild_sched_domains+0x10/0x12
    [] sched_power_savings_store+0x6c/0x7b
    [] sched_mc_power_savings_store+0x16/0x18
    [] sysdev_class_store+0x20/0x22
    [] sysfs_write_file+0x108/0x144
    [] vfs_write+0xaf/0x102
    [] sys_write+0x4d/0x74
    [] system_call_fastpath+0x16/0x1b
    [] 0xffffffffffffffff

Signed-off-by: WANG Cong 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/1313671017-4112-1-git-send-email-amwang@redhat.com
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched: Move blk_schedule_flush_plug() out of __schedule()

2011-10-03T18:40:09+00:00

commit 9c40cef2b799f9b5e7fa5de4d2ad3a0168ba118c upstream.

There is no real reason to run blk_schedule_flush_plug() with
interrupts and preemption disabled.

Move it into schedule() and call it when the task is going voluntarily
to sleep. There might be false positives when the task is woken
between that call and actually scheduling, but that's not really
different from being woken immediately after switching away.

This fixes a deadlock in the scheduler where the
blk_schedule_flush_plug() callchain enables interrupts and thereby
allows a wakeup to happen of the task that's going to sleep.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Jens Axboe 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/n/tip-dwfxtra7yg1b5r65m32ywtct@git.kernel.org
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman

sched: Separate the scheduler entry for preemption

2011-10-03T18:40:08+00:00

commit c259e01a1ec90063042f758e409cd26b2a0963c8 upstream.

Block-IO and workqueues call into notifier functions from the
scheduler core code with interrupts and preemption disabled. These
calls should be made before entering the scheduler core.

To simplify this, separate the scheduler core code into
__schedule(). __schedule() is directly called from the places which
set PREEMPT_ACTIVE and from schedule(). This allows us to add the work
checks into schedule(), so they are only called when a task voluntary
goes to sleep.

Signed-off-by: Thomas Gleixner 
Signed-off-by: Peter Zijlstra 
Cc: Tejun Heo 
Cc: Jens Axboe 
Cc: Linus Torvalds 
Link: http://lkml.kernel.org/r/20110622174918.813258321@linutronix.de
Signed-off-by: Ingo Molnar 
Signed-off-by: Greg Kroah-Hartman