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tracing: Fix initialization failure path in tracing_set_tracer()

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If tracer->init() fails, current code will leave current_tracer pointing
to an unusable tracer, which at best makes 'current_tracer' report
inaccurate value.

Fix the issue by pointing current_tracer to nop tracer, and only update
current_tracer with the new one after all the initialization succeeds.

Signed-off-by: Anton Vorontsov <anton.vorontsov@linaro.org>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Anton Vorontsov
2012-07-09 17:10:39 -07:00
committed by Greg Kroah-Hartman
parent c1743cbc8d
commit b2ad368beb
1 changed files with 4 additions and 3 deletions
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7
kernel/trace/trace.c
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@ -3172,10 +3172,10 @@ static int tracing_set_tracer(const char *buf)
} }
destroy_trace_option_files(topts); destroy_trace_option_files(topts);
current_trace = t; current_trace = &nop_trace;
topts = create_trace_option_files(current_trace); topts = create_trace_option_files(t);
if (current_trace->use_max_tr) { if (t->use_max_tr) {
int cpu; int cpu;
/* we need to make per cpu buffer sizes equivalent */ /* we need to make per cpu buffer sizes equivalent */
for_each_tracing_cpu(cpu) { for_each_tracing_cpu(cpu) {
@ -3195,6 +3195,7 @@ static int tracing_set_tracer(const char *buf)
goto out; goto out;
} }
current_trace = t;
trace_branch_enable(tr); trace_branch_enable(tr);
out: out:
mutex_unlock(&trace_types_lock); mutex_unlock(&trace_types_lock);