Commit 2b974344 authored by Chunyan Zhang's avatar Chunyan Zhang Committed by Catalin Marinas

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 345ddcc8 ("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: default avatarYonghui Yang <mark.yang@spreadtrum.com>
Signed-off-by: default avatarChunyan Zhang <zhang.chunyan@linaro.org>
Acked-by: default avatarWill Deacon <will.deacon@arm.com>
Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
parent 872c63fb
...@@ -199,19 +199,19 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val, ...@@ -199,19 +199,19 @@ static inline unsigned long __percpu_xchg(void *ptr, unsigned long val,
#define _percpu_read(pcp) \ #define _percpu_read(pcp) \
({ \ ({ \
typeof(pcp) __retval; \ typeof(pcp) __retval; \
preempt_disable(); \ preempt_disable_notrace(); \
__retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), \ __retval = (typeof(pcp))__percpu_read(raw_cpu_ptr(&(pcp)), \
sizeof(pcp)); \ sizeof(pcp)); \
preempt_enable(); \ preempt_enable_notrace(); \
__retval; \ __retval; \
}) })
#define _percpu_write(pcp, val) \ #define _percpu_write(pcp, val) \
do { \ do { \
preempt_disable(); \ preempt_disable_notrace(); \
__percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), \ __percpu_write(raw_cpu_ptr(&(pcp)), (unsigned long)(val), \
sizeof(pcp)); \ sizeof(pcp)); \
preempt_enable(); \ preempt_enable_notrace(); \
} while(0) \ } while(0) \
#define _pcp_protect(operation, pcp, val) \ #define _pcp_protect(operation, pcp, val) \
......
Markdown is supported
0%
or
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment