From: Steven Rostedt (Red Hat) Date: Tue, 26 Mar 2013 21:33:00 +0000 (-0400) Subject: tracing: Fix race with update_max_tr_single and changing tracers X-Git-Tag: firefly_0821_release~3680^2~737^2~5 X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=2930e04d00e113ae24bb2b7c2b58de7b648a62c7;p=firefly-linux-kernel-4.4.55.git tracing: Fix race with update_max_tr_single and changing tracers The commit 34600f0e9 "tracing: Fix race with max_tr and changing tracers" fixed the updating of the main buffers with the race of changing tracers, but left out the fix to the updating of just a per cpu buffer. Signed-off-by: Steven Rostedt --- diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 4f1dade56981..7ba7fc76f9eb 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -744,8 +744,11 @@ update_max_tr_single(struct trace_array *tr, struct task_struct *tsk, int cpu) return; WARN_ON_ONCE(!irqs_disabled()); - if (WARN_ON_ONCE(!current_trace->allocated_snapshot)) + if (!current_trace->allocated_snapshot) { + /* Only the nop tracer should hit this when disabling */ + WARN_ON_ONCE(current_trace != &nop_trace); return; + } arch_spin_lock(&ftrace_max_lock);