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 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>

1 files changed, 3 insertions, 3 deletions

diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
index 538ba1a58f5b..e9de8ad0bad7 100644
--- a/include/linux/tracepoint.h
+++ b/include/linux/tracepoint.h
@@ -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();                               \