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  1. 27 4月, 2009 1 次提交
    • M
      locking: Documentation: lockdep-design.txt, fix note of state bits · 992d7ced
      由 Ming Lei 提交于 
      From source code of get_usage_char(), the previous note is not correct,
so fix it.

static char get_usage_char(struct lock_class *class, enum lock_usage_bit bit)
{
	char c = '.';

	if (class->usage_mask & lock_flag(bit + 2))/*LOCK_ENABLED_##STATE*/
		c = '+';
	if (class->usage_mask & lock_flag(bit)) {/*LOCK_USED_IN_##STATE*/
		c = '-';
		if (class->usage_mask & lock_flag(bit + 2))
			c = '?';
	}

	return c;
}

note:

1) The 'bit' parameter always is passed as  LOCK_USED_IN_##STATE
   or LOCK_USED_IN_##STATE_READ , from get_usage_chars().
Signed-off-by: NMing Lei <tom.leiming@gmail.com>
LKML-Reference: <1240585806-5744-1-git-send-email-tom.leiming@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      992d7ced
  3. 23 4月, 2009 1 次提交
    • I
      locking: clarify kernel-taint warning message · b48ccb09
      由 Ingo Molnar 提交于 
      Andi Kleen reported this message triggering on non-lockdep kernels:

   Disabling lockdep due to kernel taint

Clarify the message to say 'lock debugging' - debug_locks_off()
turns off all things lock debugging, not just lockdep.

[ Impact: change kernel warning message text ]
Reported-by: NAndi Kleen <andi@firstfloor.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      b48ccb09
  5. 18 4月, 2009 2 次提交
    • S
      lockdep, x86: account for irqs enabled in paranoid_exit · 0300e7f1
      由 Steven Rostedt 提交于 
      I hit the check_flags error of lockdep:

 WARNING: at kernel/lockdep.c:2893 check_flags+0x1a7/0x1d0()
 [...]
 hardirqs last  enabled at (12567): [<ffffffff8026206a>] local_bh_enable+0xaa/0x110
 hardirqs last disabled at (12569): [<ffffffff80610c76>] int3+0x16/0x40
 softirqs last  enabled at (12566): [<ffffffff80514d2b>] lock_sock_nested+0xfb/0x110
 softirqs last disabled at (12568): [<ffffffff8058454e>] tcp_prequeue_process+0x2e/0xa0

The check_flags warning of lockdep tells me that lockdep thought interrupts
were disabled, but they were really enabled.

The numbers in the above parenthesis show the order of events:

 12566: softirqs last enabled:  lock_sock_nested
 12567: hardirqs last enabled:  local_bh_enable
 12568: softirqs last disabled: tcp_prequeue_process
 12566: hardirqs last disabled: int3

int3 is a breakpoint!

Examining this further, I have CONFIG_NET_TCPPROBE enabled which adds
break points into the kernel.

The paranoid_exit of the return of int3 does not account for enabling
interrupts on return to kernel. This code is a bit tricky since it
is also used by the nmi handler (when lockdep is off), and we must be
careful about the swapgs. We can not call kernel code after the swapgs
has been performed.

[ Impact: fix lockdep check_flags warning + self-turn-off ]
Acked-by: NPeter Zijlsta <a.p.zijlstra@chello.nl>
Signed-off-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      0300e7f1
    • P
      lockdep: more robust lockdep_map init sequence · c8a25005
      由 Peter Zijlstra 提交于 
      Steven Rostedt reported:

> OK, I think I figured this bug out. This is a lockdep issue with respect
> to tracepoints.
>
> The trace points in lockdep are called all the time. Outside the lockdep
> logic. But if lockdep were to trigger an error / warning (which this run
> did) we might be in trouble. For new locks, like the dentry->d_lock, that
> are created, they will not get a name:
>
> void lockdep_init_map(struct lockdep_map *lock, const char *name,
>                       struct lock_class_key *key, int subclass)
> {
>         if (unlikely(!debug_locks))
>                 return;
>
> When a problem is found by lockdep, debug_locks becomes false. Thus we
> stop allocating names for locks. This dentry->d_lock I had, now has no
> name. Worse yet, I have CONFIG_DEBUG_VM set, that scrambles non
> initialized memory. Thus, when the trace point was hit, it had junk for
> the lock->name, and the machine crashed.

Ah, nice catch. I think we should put at least the name in regardless.

Ensure we at least initialize the trivial entries of the depmap so that
they can be relied upon, even when lockdep itself decided to pack up and
go home.

[ Impact: fix lock tracing after lockdep warnings. ]
Reported-by: NSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: NSteven Rostedt <rostedt@goodmis.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <1239954049.23397.4156.camel@laptop>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      c8a25005
  7. 17 4月, 2009 1 次提交
  9. 14 4月, 2009 35 次提交