From 8002ea62058fd7e44575f7056a26c6b257948d03 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Thu, 18 Aug 2016 16:07:30 -0400 Subject: [PATCH] Fix: perf counter context deadlock Signed-off-by: Mathieu Desnoyers --- liblttng-ust/lttng-ust-statedump.c | 10 ++++++++++ 1 file changed, 10 insertions(+) diff --git a/liblttng-ust/lttng-ust-statedump.c b/liblttng-ust/lttng-ust-statedump.c index 2fb8f34d..644af303 100644 --- a/liblttng-ust/lttng-ust-statedump.c +++ b/liblttng-ust/lttng-ust-statedump.c @@ -590,12 +590,22 @@ int do_baddr_statedump(void *owner) * session, statedumps from different processes may be * interleaved. The vpid context should be used to identify which * events belong to which process. + * + * Grab the ust_lock outside of the RCU read-side lock because we + * perform synchronize_rcu with the ust_lock held, which can trigger + * deadlocks otherwise. */ int do_lttng_ust_statedump(void *owner) { + ust_lock_nocheck(); trace_statedump_start(owner); + ust_unlock(); + do_baddr_statedump(owner); + + ust_lock_nocheck(); trace_statedump_end(owner); + ust_unlock(); return 0; } -- 2.34.1