On 26/08/2015:09:13:02 AM, Jeff Layton wrote:
> On Wed, 26 Aug 2015 18:10:44 +0530
> Pratyush Anand <pan...@redhat.com> wrote:
>
> > `perf stat -e sunrpc:svc_xprt_do_enqueue true` results in
> >
> > Warning: unknown op '->'
> > Warning: [sunrpc:svc_xprt_do_enqueue] unknown op '->'
> >
> > Similar warning for svc_handle_xprt as well.
> >
> > Actually TP_printk() should never dereference an address saved in the ring
> > buffer that points somewhere in the kernel. There's no guarantee that that
> > object still exists (with the exception of static strings).
> >
> > Therefore change all the arguments for TP_printk(), so that it references
> > values existing in the ring buffer only.
> >
> > While doing that, also fix another possible bug when argument xprt could be
> > NULL and TP_fast_assign() tries to access it's elements.
> >
> > Signed-off-by: Pratyush Anand <pan...@redhat.com>
> > Acked-by: Steven Rostedt <rost...@goodmis.org>
> > ---
> > Changes since V1:
> > - struct sockaddr memcopied to ring buffer so that its internal element can
> > be accessed while printing %pIS.
> >
> > include/trace/events/sunrpc.h | 23 ++++++++++++++++-------
> > 1 file changed, 16 insertions(+), 7 deletions(-)
> >
> > diff --git a/include/trace/events/sunrpc.h b/include/trace/events/sunrpc.h
> > index fd1a02cb3c82..75a16fcc0795 100644
> > --- a/include/trace/events/sunrpc.h
> > +++ b/include/trace/events/sunrpc.h
> > @@ -529,18 +529,23 @@ TRACE_EVENT(svc_xprt_do_enqueue,
> >
> > TP_STRUCT__entry(
> > __field(struct svc_xprt *, xprt)
> > + __field_struct(struct sockaddr_storage, ss)
> > __field(struct svc_rqst *, rqst)
>
> nit: I think you should be able to avoid storing "rqst" now.
Yes.
>
> > + __field(int, pid)
> > + __field(unsigned long, flags)
> > ),
> >
> > TP_fast_assign(
> > - __entry->xprt = xprt;
> > + __entry->xprt = xprt,
>
> Shouldn't that line end with ';'?
>
I think, both should be OK.. I just copied this hunk from svc_xprt_dequeue.
> > + xprt ? memcpy(&__entry->ss, &xprt->xpt_remote,
> > sizeof(__entry->ss)) : memset(&__entry->ss, 0, sizeof(__entry->ss));
> > __entry->rqst = rqst;
> > + __entry->pid = rqst? rqst->rq_task->pid : 0;
> > + __entry->flags = xprt ? xprt->xpt_flags : 0;
> > ),
> >
> > TP_printk("xprt=0x%p addr=%pIScp pid=%d flags=%s", __entry->xprt,
> > - (struct sockaddr *)&__entry->xprt->xpt_remote,
> > - __entry->rqst ? __entry->rqst->rq_task->pid : 0,
> > - show_svc_xprt_flags(__entry->xprt->xpt_flags))
> > + (struct sockaddr *)&__entry->ss,
> > + __entry->pid, show_svc_xprt_flags(__entry->flags))
> > );
> >
> > TRACE_EVENT(svc_xprt_dequeue,
> > @@ -589,16 +594,20 @@ TRACE_EVENT(svc_handle_xprt,
> > TP_STRUCT__entry(
> > __field(struct svc_xprt *, xprt)
> > __field(int, len)
> > + __field_struct(struct sockaddr_storage, ss)
> > + __field(unsigned long, flags)
> > ),
> >
> > TP_fast_assign(
> > - __entry->xprt = xprt;
> > + __entry->xprt = xprt,
> > + xprt ? memcpy(&__entry->ss, &xprt->xpt_remote,
> > sizeof(__entry->ss)) : memset(&__entry->ss, 0, sizeof(__entry->ss));
> > __entry->len = len;
> > + __entry->flags = xprt ? xprt->xpt_flags : 0;
> > ),
> >
> > TP_printk("xprt=0x%p addr=%pIScp len=%d flags=%s", __entry->xprt,
> > - (struct sockaddr *)&__entry->xprt->xpt_remote, __entry->len,
> > - show_svc_xprt_flags(__entry->xprt->xpt_flags))
> > + (struct sockaddr *)&__entry->ss,
> > + __entry->len, show_svc_xprt_flags(__entry->flags))
> > );
> > #endif /* _TRACE_SUNRPC_H */
> >
>
> Looks good otherwise. Thanks for fixing this!
>
> Reviewed-by: Jeff Layton <jeff.lay...@primarydata.com>
Thanks :-)
~Pratyush
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