linux/kernel/trace
Frederic Weisbecker 07695fa04e tracing/ftrace: fix a race condition in sched_switch tracer
Impact: fix race condition in sched_switch tracer

This patch fixes a race condition in the sched_switch tracer. If
several tasks (IE: concurrent initcalls) are playing with
tracing_start_cmdline_record() and tracing_stop_cmdline_record(), the
following situation could happen:

_ Task A and B are using the same tracepoint probe. Task A holds it.
  Task B is sleeping and doesn't hold it.

_ Task A frees the sched tracer, then sched_ref is decremented to 0.

_ Task A is preempted and hadn't yet unregistered its tracepoint
  probe, then B runs.

_ B increments sched_ref, sees it's 1 and then guess it has to
  register its probe. But it has not been freed by task A.

_ A lot of bad things can happen after that...

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-11-04 17:14:04 +01:00
..
ftrace.c ftrace: perform an initialization for ftrace to enable it 2008-10-28 19:15:58 +01:00
Kconfig tracing, alpha: undefined reference to `save_stack_trace' 2008-11-03 10:12:13 +01:00
Makefile ftrace: rename FTRACE to FUNCTION_TRACER 2008-10-20 18:27:03 +02:00
ring_buffer.c trace: fix printk warning for u64 2008-10-27 11:31:58 +01:00
trace_boot.c tracing/fastboot: Enable boot tracing only during initcalls 2008-11-04 17:14:02 +01:00
trace_functions.c ftrace: rename the ftrace tracer to function 2008-10-20 18:27:04 +02:00
trace_irqsoff.c ftrace: rename FTRACE to FUNCTION_TRACER 2008-10-20 18:27:03 +02:00
trace_mmiotrace.c ftrace: preempt disable over interrupt disable 2008-10-14 10:39:09 +02:00
trace_nop.c ftrace: make work with new ring buffer 2008-10-14 10:38:57 +02:00
trace_sched_switch.c tracing/ftrace: fix a race condition in sched_switch tracer 2008-11-04 17:14:04 +01:00
trace_sched_wakeup.c ftrace: rename FTRACE to FUNCTION_TRACER 2008-10-20 18:27:03 +02:00
trace_selftest_dynamic.c ftrace: fix dynamic ftrace selftest 2008-05-23 21:13:23 +02:00
trace_selftest.c ftrace: remove daemon 2008-10-23 16:00:22 +02:00
trace_stack.c ftrace: stack tracer only record when on stack 2008-10-20 18:31:37 +02:00
trace_sysprof.c ftrace: make work with new ring buffer 2008-10-14 10:38:57 +02:00
trace.c Merge branches 'tracing/ftrace', 'tracing/markers', 'tracing/mmiotrace', 'tracing/nmisafe', 'tracing/tracepoints' and 'tracing/urgent' into tracing/core 2008-11-03 10:34:23 +01:00
trace.h ftrace: handle archs that do not support irqs_disabled_flags 2008-10-31 00:03:26 +01:00