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tracing: Use flag buffer_disabled for irqsoff tracer

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If the ring buffer is disabled and the irqsoff tracer records a trace it
will clear out its buffer and lose the data it had previously recorded.

Currently there's a callback when writing to the tracing_of file, but if
tracing is disabled via the function tracer trigger, it will not inform
the irqsoff tracer to stop recording.

By using the "mirror" flag (buffer_disabled) in the trace_array, that keeps
track of the status of the trace_array's buffer, it gives the irqsoff
tracer a fast way to know if it should record a new trace or not.
The flag may be a little behind the real state of the buffer, but it
should not affect the trace too much. It's more important for the irqsoff
tracer to be fast.

Reported-by: Dave Jones <davej@redhat.com>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
This commit is contained in:
Steven Rostedt (Red Hat) 2013-07-01 15:58:24 -04:00 • committed by Steven Rostedt
parent b04d52e368
commit 10246fa35d
2 changed files with 72 additions and 33 deletions
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4
kernel/trace/trace_irqsoff.c
View file

@ -373,7 +373,7 @@ start_critical_timing(unsigned long ip, unsigned long parent_ip)
struct trace_array_cpu *data;
unsigned long flags;
if (likely(!tracer_enabled))
if (!tracer_enabled || !tracing_is_enabled())
return;
cpu = raw_smp_processor_id();
@ -416,7 +416,7 @@ stop_critical_timing(unsigned long ip, unsigned long parent_ip)
else
return;
if (!tracer_enabled)
if (!tracer_enabled || !tracing_is_enabled())
return;
data = per_cpu_ptr(tr->trace_buffer.data, cpu);