The following commit has been merged into the locking/urgent branch of tip:
Commit-ID: 91ea62d58bd661827c328a2c6c02a87fa4aae88b Gitweb: https://git.kernel.org/tip/91ea62d58bd661827c328a2c6c02a87fa4aae88b Author: Peter Zijlstra <pet...@infradead.org> AuthorDate: Fri, 18 Dec 2020 16:39:14 +01:00 Committer: Peter Zijlstra <pet...@infradead.org> CommitterDate: Fri, 18 Dec 2020 16:53:13 +01:00 softirq: Avoid bad tracing / lockdep interaction Similar to commit: 1a63dcd8765b ("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 <h...@linux.ibm.com> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org> Tested-by: Heiko Carstens <h...@linux.ibm.com> Link: https://lkml.kernel.org/r/20201218154519.gw3...@hirez.programming.kicks-ass.net --- kernel/softirq.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/softirq.c b/kernel/softirq.c index 09229ad..0f1d3a3 100644 --- a/kernel/softirq.c +++ b/kernel/softirq.c @@ -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())) { /*
