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tracepoint: Use __idx instead of idx in DO_TRACE macro to make it unique 

After enabling KVM event tracing, almost all of trace_kvm_exit()'s
printk shows

	"kvm_exit: IRQ: ..."

even if the actual exception_type is NOT IRQ.  More specifically,
trace_kvm_exit() is defined in virt/kvm/arm/trace.h by TRACE_EVENT.

This slight problem may have existed after commit e6753f23d9
("tracepoint: Make rcuidle tracepoint callers use SRCU"). There are
two variables in trace_kvm_exit() and __DO_TRACE() which have the
same name, *idx*. Thus the actual value of *idx* will be overwritten
when tracing. Fix it by adding a simple prefix.

Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Wang Haibin <wanghaibin.wang@huawei.com>
Cc: linux-trace-devel@vger.kernel.org
Cc: stable@vger.kernel.org
Fixes: e6753f23d9 ("tracepoint: Make rcuidle tracepoint callers use SRCU")
Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Zenghui Yu <yuzenghui@huawei.com>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Zenghui Yu 2018-11-28 03:35:23 +00:00 committed by Steven Rostedt (VMware)
parent 3054426dc6
commit 0c7a52e4d4
1 changed files with 3 additions and 3 deletions
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6
include/linux/tracepoint.h
View File

@ -166,7 +166,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
struct tracepoint_func *it_func_ptr; \
void *it_func; \
void *__data; \
int __maybe_unused idx = 0; \
int __maybe_unused __idx = 0; \
\
if (!(cond)) \
return; \
@ -182,7 +182,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
* doesn't work from the idle path. \
*/ \
if (rcuidle) { \
idx = srcu_read_lock_notrace(&tracepoint_srcu); \
__idx = srcu_read_lock_notrace(&tracepoint_srcu);\
rcu_irq_enter_irqson(); \
} \
\
@ -198,7 +198,7 @@ static inline struct tracepoint *tracepoint_ptr_deref(tracepoint_ptr_t *p)
\
if (rcuidle) { \
rcu_irq_exit_irqson(); \
srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
} \
\
preempt_enable_notrace(); \