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| author | Steven Rostedt <srostedt@redhat.com> | 2008-11-11 05:07:30 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-11-11 09:40:29 +0100 |
| commit | 5aa1ba6a6c710e747838a22d798ac97a8b248745 (patch) | |
| tree | 29a0e0bfdad1a5674667dda1236099952dbf41cb /kernel/trace/trace.c | |
| parent | Merge branch 'tracing/urgent' into tracing/ftrace (diff) | |
| download | linux-5aa1ba6a6c710e747838a22d798ac97a8b248745.tar.xz linux-5aa1ba6a6c710e747838a22d798ac97a8b248745.zip | |
ftrace: prevent ftrace_special from recursion
Impact: stop ftrace_special from recursion
The ftrace_special is used to help debug areas of the kernel.
Because of this, if it is put in certain locations, the fact that
it allows recursion can become a problem if the kernel developer
using does not realize that.
This patch changes ftrace_special to not allow recursion into itself
to make it more robust.
It also changes from preempt disable interrupts disable to prevent
any loss of trace entries.
Signed-off-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/trace/trace.c')
| -rw-r--r-- | kernel/trace/trace.c | 8 |
1 files changed, 5 insertions, 3 deletions
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c index 0c22fe2d43a7..216bbe7547a4 100644 --- a/kernel/trace/trace.c +++ b/kernel/trace/trace.c @@ -960,6 +960,7 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) { struct trace_array *tr = &global_trace; struct trace_array_cpu *data; + unsigned long flags; int cpu; int pc; @@ -967,14 +968,15 @@ ftrace_special(unsigned long arg1, unsigned long arg2, unsigned long arg3) return; pc = preempt_count(); - preempt_disable_notrace(); + local_irq_save(flags); cpu = raw_smp_processor_id(); data = tr->data[cpu]; - if (likely(!atomic_read(&data->disabled))) + if (likely(atomic_inc_return(&data->disabled) == 1)) ftrace_trace_special(tr, data, arg1, arg2, arg3, pc); - preempt_enable_notrace(); + atomic_dec(&data->disabled); + local_irq_restore(flags); } #ifdef CONFIG_FUNCTION_TRACER |