Commit 285aaeac authored by Jiri Olsa's avatar Jiri Olsa Committed by Arnaldo Carvalho de Melo
Browse files

libperf: Centralize map refcnt setting 



Currently when a new map is mmapped we set its refcnt to 2 in the
perf_evlist_mmap_ops::mmap callback.

Every mmap gets its refcnt set to 2 when it's first mmaped:

  - 1 for the current user, which will be taken out by a call to
    perf_evlist__munmap_filtered(), where we find out there's
    no more data comming from kernel to this mmap.

  - 1 for the drain code where in perf_mmap__consume() the mmap
    is released if it is empty.

Move this common setup into libperf's generic code before the mmap
callback is called.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lore.kernel.org/lkml/20191007125344.14268-23-jolsa@kernel.org


Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
parent 923d0f18

tools/perf/lib/evlist.c

+15 −15
Original line number Diff line number Diff line
@@ -362,21 +362,6 @@ static int 
perf_evlist__mmap_cb_mmap(struct perf_mmap *map, struct perf_mmap_param *mp,

			  int output, int cpu)

{

	/*

	 * The last one will be done at perf_mmap__consume(), so that we

	 * make sure we don't prevent tools from consuming every last event in

	 * the ring buffer.

	 *

	 * I.e. we can get the POLLHUP meaning that the fd doesn't exist

	 * anymore, but the last events for it are still in the ring buffer,

	 * waiting to be consumed.

	 *

	 * Tools can chose to ignore this at their own discretion, but the

	 * evlist layer can't just drop it when filtering events in

	 * perf_evlist__filter_pollfd().

	 */

	refcount_set(&map->refcnt, 2);



	return perf_mmap__mmap(map, mp, output, cpu);

}
@@ -418,6 +403,21 @@ mmap_per_evsel(struct perf_evlist *evlist, struct perf_evlist_mmap_ops *ops, 
		if (*output == -1) {

			*output = fd;



			/*

			 * The last one will be done at perf_mmap__consume(), so that we

			 * make sure we don't prevent tools from consuming every last event in

			 * the ring buffer.

			 *

			 * I.e. we can get the POLLHUP meaning that the fd doesn't exist

			 * anymore, but the last events for it are still in the ring buffer,

			 * waiting to be consumed.

			 *

			 * Tools can chose to ignore this at their own discretion, but the

			 * evlist layer can't just drop it when filtering events in

			 * perf_evlist__filter_pollfd().

			 */

			refcount_set(&map->refcnt, 2);



			if (ops->mmap(map, mp, *output, evlist_cpu) < 0)

				return -1;

		} else {

tools/perf/util/mmap.c

+0 −15
Original line number Diff line number Diff line
@@ -243,21 +243,6 @@ static void perf_mmap__setup_affinity_mask(struct mmap *map, struct mmap_params 


int mmap__mmap(struct mmap *map, struct mmap_params *mp, int fd, int cpu)

{

	/*

	 * The last one will be done at perf_mmap__consume(), so that we

	 * make sure we don't prevent tools from consuming every last event in

	 * the ring buffer.

	 *

	 * I.e. we can get the POLLHUP meaning that the fd doesn't exist

	 * anymore, but the last events for it are still in the ring buffer,

	 * waiting to be consumed.

	 *

	 * Tools can chose to ignore this at their own discretion, but the

	 * evlist layer can't just drop it when filtering events in

	 * perf_evlist__filter_pollfd().

	 */

	refcount_set(&map->core.refcnt, 2);



	if (perf_mmap__mmap(&map->core, &mp->core, fd, cpu)) {

		pr_debug2("failed to mmap perf event ring buffer, error %d\n",

			  errno);

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