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| author | Frederic Weisbecker <fweisbec@gmail.com> | 2008-12-04 23:47:35 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-12-05 14:47:43 +0100 |
| commit | ff32504fdc56407654584ef187b20022c94a3486 (patch) | |
| tree | 71f265bbc27f603732e3791bb24896e450489083 /kernel/trace | |
| parent | 970987beb9c99ca806edc464518d411cc399fb4d (diff) | |
| download | blackbird-op-linux-ff32504fdc56407654584ef187b20022c94a3486.tar.gz blackbird-op-linux-ff32504fdc56407654584ef187b20022c94a3486.zip | |
tracing/ftrace: don't insert TRACE_PRINT during selftests
Impact: fix tracer selfstests false results
After setting a ftrace_printk somewhere in th kernel, I saw the
Function tracer selftest failing.
When a selftest occurs, the ring buffer is lurked to see if
some entries were inserted. But concurrent insertion such as
ftrace_printk could occured at the same time and could give
false positive or negative results.
This patch prevent prevent from TRACE_PRINT entries insertion
during selftests.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace')
| -rw-r--r-- | kernel/trace/trace.c | 13 |
1 files changed, 12 insertions, 1 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index ea38652d631c..5dca6ef1fbeb 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -44,6 +44,14 @@ unsigned long __read_mostly tracing_max_latency = (cycle_t)ULONG_MAX; unsigned long __read_mostly tracing_thresh; +/* We need to change this state when a selftest is running. + * A selftest will lurk into the ring-buffer to count the + * entries inserted during the selftest although some concurrent + * insertions into the ring-buffer such as ftrace_printk could occurred + * at the same time, giving false positive or negative results. + */ +static atomic_t tracing_selftest_running = ATOMIC_INIT(0); + /* For tracers that don't implement custom flags */ static struct tracer_opt dummy_tracer_opt[] = { { } @@ -589,6 +597,8 @@ int register_tracer(struct tracer *type) struct tracer *saved_tracer = current_trace; struct trace_array *tr = &global_trace; int i; + + atomic_set(&tracing_selftest_running, 1); /* * Run a selftest on this tracer. * Here we reset the trace buffer, and set the current @@ -603,6 +613,7 @@ int register_tracer(struct tracer *type) /* the test is responsible for initializing and enabling */ pr_info("Testing tracer %s: ", type->name); ret = type->selftest(type, tr); + atomic_set(&tracing_selftest_running, 0); /* the test is responsible for resetting too */ current_trace = saved_tracer; if (ret) { @@ -3594,7 +3605,7 @@ int trace_vprintk(unsigned long ip, int depth, const char *fmt, va_list args) unsigned long flags, irq_flags; int cpu, len = 0, size, pc; - if (tracing_disabled) + if (tracing_disabled || atomic_read(&tracing_selftest_running)) return 0; pc = preempt_count(); |
