From 283740c619d211e34572cc93c8cdba92ccbdb9cc Mon Sep 17 00:00:00 2001 From: Steven Rostedt Date: Fri, 12 Mar 2010 19:48:41 -0500 Subject: [PATCH] tracing: Use same local variable when resetting the ring buffer In the ftrace code that resets the ring buffer it references the buffer with a local variable, but then uses the tr->buffer as the parameter to reset. If the wakeup tracer is running, which can switch the tr->buffer with the max saved buffer, this can break the requirement of disabling the buffer before the reset. buffer = tr->buffer; ring_buffer_record_disable(buffer); synchronize_sched(); __tracing_reset(tr->buffer, cpu); If the tr->buffer is swapped, then the reset is not happening to the buffer that was disabled. This will cause the ring buffer to fail. Found with Li Zefan's ftrace_stress_test. Cc: stable@kernel.org Reported-by: Lai Jiangshan Signed-off-by: Steven Rostedt --- kernel/trace/trace.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 6af8d7bc953b..60de37bd0f75 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -840,10 +840,10 @@ out: mutex_unlock(&trace_types_lock); } -static void __tracing_reset(struct trace_array *tr, int cpu) +static void __tracing_reset(struct ring_buffer *buffer, int cpu) { ftrace_disable_cpu(); - ring_buffer_reset_cpu(tr->buffer, cpu); + ring_buffer_reset_cpu(buffer, cpu); ftrace_enable_cpu(); } @@ -855,7 +855,7 @@ void tracing_reset(struct trace_array *tr, int cpu) /* Make sure all commits have finished */ synchronize_sched(); - __tracing_reset(tr, cpu); + __tracing_reset(buffer, cpu); ring_buffer_record_enable(buffer); } @@ -873,7 +873,7 @@ void tracing_reset_online_cpus(struct trace_array *tr) tr->time_start = ftrace_now(tr->cpu); for_each_online_cpu(cpu) - __tracing_reset(tr, cpu); + __tracing_reset(buffer, cpu); ring_buffer_record_enable(buffer); } -- 2.20.1