Messages in this thread Patch in this message | | | Date | Sun, 16 Nov 2008 05:59:52 +0100 | From | Frederic Weisbecker <> | Subject | [PATCH 3/4] tracing/branch-tracer: Fix a trace recursion on branch tracer |
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Impact: Make the branch tracer use raw irq save/restore
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> Cc: Steven Rostedt <rostedt@goodmis.org> --- kernel/trace/trace_branch.c | 4 ++-- 1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/kernel/trace/trace_branch.c b/kernel/trace/trace_branch.c index 44bd395..23f9b02 100644 --- a/kernel/trace/trace_branch.c +++ b/kernel/trace/trace_branch.c @@ -41,7 +41,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) if (unlikely(!tr)) return; - local_irq_save(flags); + raw_local_irq_save(flags); cpu = raw_smp_processor_id(); if (atomic_inc_return(&tr->data[cpu]->disabled) != 1) goto out; @@ -73,7 +73,7 @@ probe_likely_condition(struct ftrace_branch_data *f, int val, int expect) out: atomic_dec(&tr->data[cpu]->disabled); - local_irq_restore(flags); + raw_local_irq_restore(flags); } static inline -- 1.5.2.5
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