On Wed, 28 Nov 2018 03:35:23 +0000
Zenghui Yu <yuzenghui@xxxxxxxxxx> wrote:
> 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.
Nice catch! I'll apply it tomorrow and start testing it then.
Thanks!
-- Steve
>
> Signed-off-by: Zenghui Yu <yuzenghui@xxxxxxxxxx>
> Cc: Joel Fernandes <joel@xxxxxxxxxxxxxxxxx>
> Cc: Wang Haibin <wanghaibin.wang@xxxxxxxxxx>
> Cc: linux-trace-devel@xxxxxxxxxxxxxxx
> ---
> include/linux/tracepoint.h | 6 +++---
> 1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/include/linux/tracepoint.h b/include/linux/tracepoint.h
> index 538ba1a..e9de8ad 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(); \
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