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softirq/preempt: Add missing current->preempt_disable_ip update 

While debugging some "sleeping function called from invalid context" bug I
realized that the debugging message "Preemption disabled at:" pointed to
an incorrect function.

In particular if the last function/action that disabled preemption was
spin_lock_bh() then current->preempt_disable_ip won't be updated.

The reason for this is that __local_bh_disable_ip() will increase
preempt_count manually instead of calling preempt_count_add(), which
would handle the update correctly.

It look like the manual handling was done to work around some lockdep issue.

So add the missing update of current->preempt_disable_ip to
__local_bh_disable_ip() as well.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20150107090441.GC4365@osiris
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Heiko Carstens 2015-01-07 10:04:41 +01:00 committed by Ingo Molnar
parent 036cc30c6b
commit 0f1ba9a2ce
1 changed files with 5 additions and 1 deletions
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6
kernel/softirq.c
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@ -114,8 +114,12 @@ void __local_bh_disable_ip(unsigned long ip, unsigned int cnt)
trace_softirqs_off(ip);
raw_local_irq_restore(flags);
if (preempt_count() == cnt)
if (preempt_count() == cnt) {
#ifdef CONFIG_DEBUG_PREEMPT
current->preempt_disable_ip = get_parent_ip(CALLER_ADDR1);
#endif
trace_preempt_off(CALLER_ADDR0, get_parent_ip(CALLER_ADDR1));
}
}
EXPORT_SYMBOL(__local_bh_disable_ip);
#endif /* CONFIG_TRACE_IRQFLAGS */