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authorSteven Rostedt <srostedt@redhat.com>2010-03-12 19:48:41 -0500
committerSteven Rostedt <rostedt@goodmis.org>2010-03-12 20:29:20 -0500
commit283740c619d211e34572cc93c8cdba92ccbdb9cc (patch)
tree3bdce475017ff9a5fe82c6d214d27b27e555320c
parentea14eb714041d40fcc5180b5a586034503650149 (diff)
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 <laijs@cn.fujitsu.com> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
-rw-r--r--kernel/trace/trace.c8
1 files changed, 4 insertions, 4 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 6af8d7bc953..60de37bd0f7 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);
}