Re: [PATCH] tracepoint: fix bad trace value in trace_kvm_exit()

[Joel Fernandes <joel@joelfernandes.org>]

On Wed, Nov 28, 2018 at 09:34:42PM -0500, Steven Rostedt wrote:
> On Thu, 29 Nov 2018 10:21:55 +0800
> Zenghui Yu <yuzenghui@huawei.com> wrote:
> 
> > On 2018/11/28 11:54, Steven Rostedt wrote:
> > > On Wed, 28 Nov 2018 03:35:23 +0000
> > > Zenghui Yu <yuzenghui@huawei.com> 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 Steven!
> > 
> 
> FYI, I renamed your subject to:
> 
>  tracepoint: Use __idx instead of idx in DO_TRACE macro to make it unique
> 
> to make the name more specific to the fix and not the symptom.
> 
> Thanks!

Thanks!

Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org>

 - Joel