tracing/branch-tracer: fix a trace recursion on branch tracer
authorFrederic Weisbecker <fweisbec@gmail.com>
Sun, 16 Nov 2008 04:59:52 +0000 (05:59 +0100)
committerIngo Molnar <mingo@elte.hu>
Sun, 16 Nov 2008 06:55:59 +0000 (07:55 +0100)
commit072b40a15616fe6bea68466e6bffcfcbf5c8f26f
tree0efdcf29a712e8f381a56e57f6a89cb7ca7be901
parentc91add5fa68ea9b1f2923b3788c5dae0e60e1f6b
tracing/branch-tracer: fix a trace recursion on branch tracer

Impact: fix crash when enabling the branch-tracer

When the branch tracer inserts an event through
probe_likely_condition(), it calls local_irq_save() and then results
in a trace recursion.

local_irq_save() -> trace_hardirqs_off() -> trace_hardirqs_off_caller()
-> unlikely()

The trace_branch.c file is protected by DISABLE_BRANCH_PROFILING but
that doesn't prevent from external call to functions that use
unlikely().

My box crashed each time I tried to set this tracer (sudden and hard
reboot).

Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
kernel/trace/trace_branch.c