Re: [PATCH v1 1/5] perf: add context parameter to perf_event overflow handler

[Avi Kivity <avi@redhat.com>]

On 06/03/2011 05:41 PM, Peter Zijlstra wrote:
> On Wed, 2011-05-11 at 11:55 -0400, Avi Kivity wrote:
> >  +++ b/include/linux/perf_event.h
> >  @@ -709,7 +709,9 @@ struct perf_buffer {
> >
> >   struct perf_sample_data;
> >
> >  -typedef void (*perf_overflow_handler_t)(struct perf_event *, int,
> >  +typedef void (*perf_overflow_handler_t)(void *context,
> >  +                                       struct perf_event *event,
> >  +                                       int,
> >                                          struct perf_sample_data *,
> >                                          struct pt_regs *regs);
> >
> >  @@ -855,6 +857,7 @@ struct perf_event {
> >          u64                             id;
> >
> >          perf_overflow_handler_t         overflow_handler;
> >  +       void                            *overflow_handler_context;
> >
> >   #ifdef CONFIG_EVENT_TRACING
> >          struct ftrace_event_call        *tp_event;
>
> If you're adding a pointer here, then why pass it along in the callback
> thing if it already has the perf_event *?
>
> It seems to me the callback can easily do
> event->overflow_handler_context if it needs the thing.

Makes sense.  Will update.

(I would have preferred a caller-allocated perf_event with 
container_of(), but that's a huge change).

-- 
error compiling committee.c: too many arguments to function