Hi Steven,
On 24/02/15 14:09, Steven Rostedt wrote:
> On Tue, 24 Feb 2015 11:47:56 +0000
> James Hogan <james.hogan@xxxxxxxxxx> wrote:
>
>
>
>> TP_printk("xprt=0x%p addr=%pIScp pid=%d flags=%s", __entry->xprt,
>> - (struct sockaddr *)&__entry->xprt->xpt_remote,
>
> There's actually nothing wrong with the above even if xprt is NULL.
> It's not dereferencing the structure, it is just getting the address of
> what would be dereference.
I think that corresponds to the %pIScp format which I presumed does
dereference the pointer?
Looking at Documentation/printk-formats.txt I see:
> IPv4/IPv6 addresses (generic, with port, flowinfo, scope):
> ...
> %pISpc 1.2.3.4:12345 or [1:2:3:4:5:6:7:8]:12345
Same applies below. Should these formats still be avoided?
Thanks for reviewing,
Cheers
James
>
>> - __entry->rqst ? __entry->rqst->rq_task->pid : 0,
>> - show_svc_xprt_flags(__entry->xprt->xpt_flags))
>> + (struct sockaddr *)&__entry->ss,
>
> The above is meaningless. You just printed the address of the ring
> buffer and this will be different (and useless) every time.
>
>> + __entry->pid,
>> + show_svc_xprt_flags(__entry->flags))
>> );
>>
>> TRACE_EVENT(svc_xprt_dequeue,
>> @@ -562,17 +566,21 @@ TRACE_EVENT(svc_handle_xprt,
>>
>> TP_STRUCT__entry(
>> __field(struct svc_xprt *, xprt)
>> + __field_struct(struct sockaddr_storage, ss)
>> + __field(unsigned long, flags);
>> __field(int, len)
>> ),
>>
>> TP_fast_assign(
>> __entry->xprt = xprt;
>> + xprt ? memcpy(&__entry->ss, &xprt->xpt_remote, sizeof(__entry->ss)) : memset(&__entry->ss, 0, sizeof(__entry->ss));
>> + __entry->flags = xprt ? xprt->xpt_flags : 0;
>> __entry->len = len;
>> ),
>>
>> 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,
>
> Ditto.
>
> Don't use field_struct() unless you really know what you are doing.
> This is copying the entire struct into the ring buffer and only using
> the address of that struct. Which not only is useless, but wastes a lot
> of space in the ring buffer.
>
> -- Steve
>
>> + show_svc_xprt_flags(__entry->flags))
>> );
>> #endif /* _TRACE_SUNRPC_H */
>>
>
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