Messages in this thread | | | Date | Fri, 9 Sep 2016 11:07:33 +0100 | From | Will Deacon <> | Subject | Re: [PATCH] arm64: use preempt_disable_notrace in _percpu_read/write |
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On Thu, Sep 08, 2016 at 08:46:42PM +0800, Chunyan Zhang wrote: > When debug preempt or preempt tracer is enabled, preempt_count_add/sub() > can be traced by function and function graph tracing, and > preempt_disable/enable() would call preempt_count_add/sub(), so in Ftrace > subsystem we should use preempt_disable/enable_notrace instead. > > In the commit 345ddcc882d8 ("ftrace: Have set_ftrace_pid use the bitmap > like events do") the function this_cpu_read() was added to > trace_graph_entry(), and if this_cpu_read() calls preempt_disable(), graph > tracer will go into a recursive loop, even if the tracing_on is > disabled. > > So this patch change to use preempt_enable/disable_notrace instead in > this_cpu_read(). > > Since Yonghui Yang helped a lot to find the root cause of this problem, > so also add his SOB. > > Signed-off-by: Yonghui Yang <mark.yang@spreadtrum.com> > Signed-off-by: Chunyan Zhang <zhang.chunyan@linaro.org> > --- > arch/arm64/include/asm/percpu.h | 8 ++++---- > 1 file changed, 4 insertions(+), 4 deletions(-)
Looks good to me:
Acked-by: Will Deacon <will.deacon@arm.com>
However, don't you need to make a similar change to asm-generic/percpu.h for other architectures (e.g. arch/arm/)?
Will
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