From e6f3faa734a00c606b7b06c6b9f15e5627d3245b Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 23 Aug 2017 13:23:30 +0200 Subject: locking/lockdep: Fix workqueue crossrelease annotation The new completion/crossrelease annotations interact unfavourable with the extant flush_work()/flush_workqueue() annotations. The problem is that when a single work class does: wait_for_completion(&C) and complete(&C) in different executions, we'll build dependencies like: lock_map_acquire(W) complete_acquire(C) and lock_map_acquire(W) complete_release(C) which results in the dependency chain: W->C->W, which lockdep thinks spells deadlock, even though there is no deadlock potential since works are ran concurrently. One possibility would be to change the work 'lock' to recursive-read, but that would mean hitting a lockdep limitation on recursive locks. Also, unconditinoally switching to recursive-read here would fail to detect the actual deadlock on single-threaded workqueues, which do have a problem with this. For now, forcefully disregard these locks for crossrelease. Signed-off-by: Peter Zijlstra (Intel) Acked-by: Tejun Heo Cc: Linus Torvalds Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: boqun.feng@gmail.com Cc: byungchul.park@lge.com Cc: david@fromorbit.com Cc: johannes@sipsolutions.net Cc: oleg@redhat.com Signed-off-by: Ingo Molnar --- include/linux/irqflags.h | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'include/linux/irqflags.h') diff --git a/include/linux/irqflags.h b/include/linux/irqflags.h index 5fdd93bb9300..9bc050bc81b2 100644 --- a/include/linux/irqflags.h +++ b/include/linux/irqflags.h @@ -26,7 +26,7 @@ # define trace_hardirq_enter() \ do { \ current->hardirq_context++; \ - crossrelease_hist_start(XHLOCK_HARD); \ + crossrelease_hist_start(XHLOCK_HARD, 0);\ } while (0) # define trace_hardirq_exit() \ do { \ @@ -36,7 +36,7 @@ do { \ # define lockdep_softirq_enter() \ do { \ current->softirq_context++; \ - crossrelease_hist_start(XHLOCK_SOFT); \ + crossrelease_hist_start(XHLOCK_SOFT, 0);\ } while (0) # define lockdep_softirq_exit() \ do { \ -- cgit v1.2.3