Messages in this thread | | | Date | Tue, 22 Apr 2014 16:25:17 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH 03/16] perf, mmap: Factor out perf_alloc/free_rb() |
| |
On Mon, Apr 07, 2014 at 05:04:25PM +0200, Jean Pihet wrote: > From: Robert Richter <robert.richter@linaro.org> > > Factor out code to allocate and deallocate ringbuffers. We need this > later to setup the sampling buffer for persistent events. > > While at this, replacing get_current_user() with get_uid(user). > > Signed-off-by: Robert Richter <robert.richter@linaro.org> > Signed-off-by: Robert Richter <rric@kernel.org> > Signed-off-by: Jean Pihet <jean.pihet@linaro.org> > --- > kernel/events/core.c | 77 +++++++++++++++++++++++++++++------------------- > kernel/events/internal.h | 3 ++ > 2 files changed, 50 insertions(+), 30 deletions(-) > > diff --git a/kernel/events/core.c b/kernel/events/core.c > index 5eaba42..22ec8f0 100644 > --- a/kernel/events/core.c > +++ b/kernel/events/core.c > @@ -3193,7 +3193,45 @@ static void free_event_rcu(struct rcu_head *head) > } > > static void ring_buffer_put(struct ring_buffer *rb); > +static void ring_buffer_attach(struct perf_event *event, struct ring_buffer *rb); > static void ring_buffer_detach(struct perf_event *event, struct ring_buffer *rb); > +static void perf_event_init_userpage(struct perf_event *event); > + > +/* > + * Must be called with &event->mmap_mutex held. event->rb must be > + * NULL. perf_alloc_rb() requires &event->mmap_count to be incremented > + * on success which corresponds to &rb->mmap_count that is initialized > + * with 1. > + */ > +int perf_alloc_rb(struct perf_event *event, int nr_pages, int flags) > +{ > + struct ring_buffer *rb;
lockdep_assert_held(&event->mmap_mutex); WARN_ON(event->rb);
> + > + rb = rb_alloc(nr_pages, > + event->attr.watermark ? event->attr.wakeup_watermark : 0, > + event->cpu, flags); > + if (!rb) > + return -ENOMEM; > + > + atomic_set(&rb->mmap_count, 1); > + ring_buffer_attach(event, rb); > + rcu_assign_pointer(event->rb, rb); > + > + perf_event_init_userpage(event); > + perf_event_update_userpage(event); > + > + return 0; > +} > + > +/* Must be called with &event->mmap_mutex held. event->rb must be set. */ > +void perf_free_rb(struct perf_event *event) > +{ > + struct ring_buffer *rb = event->rb;
lockdep_assert_held(&event->mmap_mutex);
> + rcu_assign_pointer(event->rb, NULL); > + ring_buffer_detach(event, rb); > + ring_buffer_put(rb); > +}
| |