On 9 September 2016 at 18:07, Will Deacon <[email protected]> wrote: > 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 <[email protected]> >> Signed-off-by: Chunyan Zhang <[email protected]> >> --- >> arch/arm64/include/asm/percpu.h | 8 ++++---- >> 1 file changed, 4 insertions(+), 4 deletions(-) > > Looks good to me: > > Acked-by: Will Deacon <[email protected]> > > However, don't you need to make a similar change to asm-generic/percpu.h > for other architectures (e.g. arch/arm/)?
Yes, I will send out another patch to fix that. Thanks, Chunyan > > Will
