linux-toradex.git/kernel/lockdep.c, branch v2.6.25-rc2

softlockup: automatically detect hung TASK_UNINTERRUPTIBLE tasks

2008-01-25T20:08:02+00:00

this patch extends the soft-lockup detector to automatically
detect hung TASK_UNINTERRUPTIBLE tasks. Such hung tasks are
printed the following way:

 ------------------>
 INFO: task prctl:3042 blocked for more than 120 seconds.
 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message
 prctl         D fd5e3793     0  3042   2997
        f6050f38 00000046 00000001 fd5e3793 00000009 c06d8264 c06dae80 00000286
        f6050f40 f6050f00 f7d34d90 f7d34fc8 c1e1be80 00000001 f6050000 00000000
        f7e92d00 00000286 f6050f18 c0489d1a f6050f40 00006605 00000000 c0133a5b
 Call Trace:
  [] schedule_timeout+0x6d/0x8b
  [] schedule_timeout_uninterruptible+0x15/0x17
  [] msleep+0x10/0x16
  [] sys_prctl+0x30/0x1e2
  [] sysenter_past_esp+0x5f/0xa5
  =======================
 2 locks held by prctl/3042:
 #0:  (&sb->s_type->i_mutex_key#5){--..}, at: [] do_fsync+0x38/0x7a
 #1:  (jbd_handle){--..}, at: [] journal_start+0xc7/0xe9
 <------------------

the current default timeout is 120 seconds. Such messages are printed
up to 10 times per bootup. If the system has crashed already then the
messages are not printed.

if lockdep is enabled then all held locks are printed as well.

this feature is a natural extension to the softlockup-detector (kernel
locked up without scheduling) and to the NMI watchdog (kernel locked up
with IRQs disabled).

[ Gautham R Shenoy : CPU hotplug fixes. ]
[ Andrew Morton : build warning fix. ]

Signed-off-by: Ingo Molnar 
Signed-off-by: Arjan van de Ven

lockdep: fix kernel crash on module unload

2008-01-24T16:01:09+00:00

Michael Wu noticed in his lkml post at

    http://marc.info/?l=linux-kernel&m=119396182726091&w=2

that certain wireless drivers ended up having their name in module
memory, which would then crash the kernel on module unload.

The patch he proposed was a bit clumsy in that it increased the size of
a lockdep entry significantly; the patch below tries another approach,
it checks, on module teardown, if the name of a class is in module space
and then zaps the class.  This is very similar to what we already do
with keys that are in module space.

Signed-off-by: Arjan van de Ven 
Signed-off-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Signed-off-by: Linus Torvalds

lockdep: fix internal double unlock during self-test

2008-01-16T08:51:58+00:00

Lockdep, during self-test (when it was simulating double unlocks) was
sometimes unconditionally unlocking a spinlock when it had not been
locked. This won't work for ticket locks.

Signed-off-by: Nick Piggin 
Signed-off-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra

lockdep: make cli/sti annotation warnings clearer

2007-12-07T18:02:47+00:00

make cli/sti annotation warnings easier to interpret.

Signed-off-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra

lockdep: in_range() fix

2007-12-05T14:46:09+00:00

Torsten Kaiser wrote:

| static inline int in_range(const void *start, const void *addr, const void *end)
| {
|         return addr >= start && addr <= end;
| }
| This  will return true, if addr is in the range of start (including)
| to end (including).
|
| But debug_check_no_locks_freed() seems does:
| const void *mem_to = mem_from + mem_len
| -> mem_to is the last byte of the freed range, that fits in_range
| lock_from = (void *)hlock->instance;
| -> first byte of the lock
| lock_to = (void *)(hlock->instance + 1);
| -> first byte of the next lock, not last byte of the lock that is being checked!
|
| The test is:
| if (!in_range(mem_from, lock_from, mem_to) &&
|                                         !in_range(mem_from, lock_to, mem_to))
|                         continue;
| So it tests, if the first byte of the lock is in the range that is freed ->OK
| And if the first byte of the *next* lock is in the range that is freed
| -> Not OK.

We can also simplify in_range checks, we need only 2 comparisons, not 4.
If the lock is not in memory range, it should be either at the left of range
or at the right.

Signed-off-by: Oleg Nesterov 
Signed-off-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra

lockdep: fix debug_show_all_locks()

2007-12-05T14:46:09+00:00

fix the oops that can be seen in:

   http://bugzilla.kernel.org/attachment.cgi?id=13828&action=view

it is not safe to print the locks of running tasks.

(even with this fix we have a small race - but this is a debug
 function after all.)

Signed-off-by: Ingo Molnar 
Signed-off-by: Peter Zijlstra

lockdep: fix a typo in the __lock_acquire comment

2007-10-28T19:47:01+00:00

Fix a typo in the __lock_acquire comment.

Signed-off-by: Gautham R Shenoy 
Signed-off-by: Peter Zijlstra 
Signed-off-by: Ingo Molnar

Use helpers to obtain task pid in printks

2007-10-19T18:53:43+00:00

The task_struct->pid member is going to be deprecated, so start
using the helpers (task_pid_nr/task_pid_vnr/task_pid_nr_ns) in
the kernel.

The first thing to start with is the pid, printed to dmesg - in
this case we may safely use task_pid_nr(). Besides, printks produce
more (much more) than a half of all the explicit pid usage.

[akpm@linux-foundation.org: git-drm went and changed lots of stuff]
Signed-off-by: Pavel Emelyanov 
Cc: Dave Airlie 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

workqueue: debug flushing deadlocks with lockdep

2007-10-19T18:53:38+00:00

In the following scenario:

code path 1:
  my_function() -> lock(L1); ...; flush_workqueue(); ...

code path 2:
  run_workqueue() -> my_work() -> ...; lock(L1); ...

you can get a deadlock when my_work() is queued or running
but my_function() has acquired L1 already.

This patch adds a pseudo-lock to each workqueue to make lockdep
warn about this scenario.

[akpm@linux-foundation.org: coding-style fixes]
Signed-off-by: Johannes Berg 
Acked-by: Oleg Nesterov 
Acked-by: Ingo Molnar 
Acked-by: Peter Zijlstra 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

lockdep: syscall exit check

2007-10-11T20:11:12+00:00

Provide a check to validate that we do not hold any locks when switching
back to user-space.

Signed-off-by: Peter Zijlstra 
Signed-off-by: Ingo Molnar