[PATCH 4.19 09/41] tracepoint: Use __idx instead of idx in DO_TRACE macro to make it unique

Greg Kroah-Hartman
2018-12-06T14:41:11Z

From: Zenghui Yu <yuzenghui@huawei.com>

commit 0c7a52e4d4b5c4d35b31f3c3ad32af814f1bf491 upstream.

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 e6753f23d961
("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: e6753f23d961 ("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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
include/linux/tracepoint.h | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -166,7 +166,7 @@ static inline struct tracepoint *tracepo
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 *tracepo
* 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 *tracepo
\
if (rcuidle) { \
rcu_irq_exit_irqson(); \
- srcu_read_unlock_notrace(&tracepoint_srcu, idx);\
+ srcu_read_unlock_notrace(&tracepoint_srcu, __idx);\
} \
\
preempt_enable_notrace(); \