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authorChunyan Zhang <zhang.chunyan@linaro.org>2016-09-08 20:46:42 +0800
committerCatalin Marinas <catalin.marinas@arm.com>2016-09-09 12:34:47 +0100
commit2b9743441a312e0b0a2d87deae363eccbe9d0f00 (patch)
tree4545db239efeb695ced5c8b1069d82d63d32be39 /arch
parent872c63fbf9e153146b07f0cece4da0d70b283eeb (diff)
downloadlinux-2b9743441a312e0b0a2d87deae363eccbe9d0f00.tar.bz2
arm64: use preempt_disable_notrace in _percpu_read/write
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> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Diffstat (limited to 'arch')
-rw-r--r--arch/arm64/include/asm/percpu.h8
1 files changed, 4 insertions, 4 deletions
diff --git a/arch/arm64/include/asm/percpu.h b/arch/arm64/include/asm/percpu.h
index 0a456bef8c79..2fee2f59288c 100644
--- a/arch/arm64/include/asm/percpu.h
+++ b/arch/arm64/include/asm/percpu.h
@@ -199,19 +199,19 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val,
#define _percpu_read(pcp) \
({ \
typeof(pcp) __retval; \
- preempt_disable(); \
+ preempt_disable_notrace(); \
__retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), \
sizeof(pcp)); \
- preempt_enable(); \
+ preempt_enable_notrace(); \
__retval; \
})
#define _percpu_write(pcp, val) \
do { \
- preempt_disable(); \
+ preempt_disable_notrace(); \
__percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), \
sizeof(pcp)); \
- preempt_enable(); \
+ preempt_enable_notrace(); \
} while(0) \
#define _pcp_protect(operation, pcp, val) \