Commit 0c7a52e4 authored Nov 28, 2018 by Zenghui Yu Committed by Steven Rostedt (VMware) Nov 29, 2018

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 e6753f23
("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: e6753f23 ("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>

parent 3054426d

include/linux/tracepoint.h

+3 −3

Original line number	Diff line number	Diff line
		@@ -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(); \

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