korg/linux
0
0
Fork 0
mirror of https://mirrors.bfsu.edu.cn/git/linux.git synced 2024-11-30 07:34:12 +08:00
Code Issues Packages Projects Releases Wiki Activity

arm64: use preempt_disable_notrace in _percpu_read/write

Browse Source 
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 345ddcc882 ("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>
This commit is contained in:
Chunyan Zhang 2016-09-08 20:46:42 +08:00 committed by Catalin Marinas
parent 872c63fbf9
commit 2b9743441a
1 changed files with 4 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

8
arch/arm64/include/asm/percpu.h
View File

@ -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) \