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softirq: Avoid bad tracing / lockdep interaction 

Similar to commit:

  1a63dcd876 ("softirq: Reorder trace_softirqs_on to prevent lockdep splat")

__local_bh_enable_ip() can also call into tracing with inconsistent
state. Unlike that commit we don't need to bother about the tracepoint
because 'cnt-1' never matches preempt_count() (by construction).

Reported-by: Heiko Carstens <hca@linux.ibm.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Tested-by: Heiko Carstens <hca@linux.ibm.com>
Link: https://lkml.kernel.org/r/20201218154519.GW3092@hirez.programming.kicks-ass.net
zero-sugar-mainline-defconfig
Peter Zijlstra 2020-12-18 16:39:14 +01:00
parent 441fa34097
commit 91ea62d58b
1 changed files with 1 additions and 1 deletions
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kernel/softirq.c
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@ -185,7 +185,7 @@ void __local_bh_enable_ip(unsigned long ip, unsigned int cnt)
* Keep preemption disabled until we are done with
* softirq processing:
*/
preempt_count_sub(cnt - 1);
__preempt_count_sub(cnt - 1);
if (unlikely(!in_interrupt() && local_softirq_pending())) {
/*