libperf: Adopt perf_mmap__consume() function from tools/perf

Move perf_mmap__consume() vrom tools/perf to libperf and export it in
the perf/mmap.h header.

Move also the needed helpers perf_mmap__write_tail(),
perf_mmap__read_head() and perf_mmap__empty().

Signed-off-by: Jiri 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/20191007125344.14268-10-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

5 files changed, 49 insertions, 2 deletions

diff --git a/tools/perf/lib/Makefile b/tools/perf/lib/Makefile
index 85ccb8c439a47..0889c9c3ec19d 100644
--- a/tools/perf/lib/Makefile
+++ b/tools/perf/lib/Makefile
@@ -172,8 +172,9 @@ install_headers:
 		$(call do_install,include/perf/cpumap.h,$(prefix)/include/perf,644); \
 		$(call do_install,include/perf/threadmap.h,$(prefix)/include/perf,644); \
 		$(call do_install,include/perf/evlist.h,$(prefix)/include/perf,644); \
-		$(call do_install,include/perf/evsel.h,$(prefix)/include/perf,644);
-		$(call do_install,include/perf/event.h,$(prefix)/include/perf,644);
+		$(call do_install,include/perf/evsel.h,$(prefix)/include/perf,644); \
+		$(call do_install,include/perf/event.h,$(prefix)/include/perf,644); \
+		$(call do_install,include/perf/mmap.h,$(prefix)/include/perf,644);
 
 install_pkgconfig: $(LIBPERF_PC)
 	$(call QUIET_INSTALL, $(LIBPERF_PC)) \
diff --git a/tools/perf/lib/include/internal/mmap.h b/tools/perf/lib/include/internal/mmap.h
index bf9cc7d005ab3..ee536c4441bb9 100644
--- a/tools/perf/lib/include/internal/mmap.h
+++ b/tools/perf/lib/include/internal/mmap.h
@@ -49,4 +49,6 @@ void perf_mmap__munmap(struct perf_mmap *map);
 void perf_mmap__get(struct perf_mmap *map);
 void perf_mmap__put(struct perf_mmap *map);
 
+u64 perf_mmap__read_head(struct perf_mmap *map);
+
 #endif /* __LIBPERF_INTERNAL_MMAP_H */
diff --git a/tools/perf/lib/include/perf/mmap.h b/tools/perf/lib/include/perf/mmap.h
new file mode 100644
index 0000000000000..d3678d1834d9c
--- /dev/null
+++ b/tools/perf/lib/include/perf/mmap.h
@@ -0,0 +1,11 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef __LIBPERF_MMAP_H
+#define __LIBPERF_MMAP_H
+
+#include <perf/core.h>
+
+struct perf_mmap;
+
+LIBPERF_API void perf_mmap__consume(struct perf_mmap *map);
+
+#endif /* __LIBPERF_MMAP_H */
diff --git a/tools/perf/lib/libperf.map b/tools/perf/lib/libperf.map
index ab8dbde1136cc..d7b327f224e25 100644
--- a/tools/perf/lib/libperf.map
+++ b/tools/perf/lib/libperf.map
@@ -40,6 +40,7 @@ LIBPERF_0.0.1 {
 		perf_evlist__next;
 		perf_evlist__set_maps;
 		perf_evlist__poll;
+		perf_mmap__consume;
 	local:
 		*;
 };
diff --git a/tools/perf/lib/mmap.c b/tools/perf/lib/mmap.c
index 89c1e0e8b897b..4cada1c89fdb9 100644
--- a/tools/perf/lib/mmap.c
+++ b/tools/perf/lib/mmap.c
@@ -1,5 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <sys/mman.h>
+#include <linux/ring_buffer.h>
+#include <linux/perf_event.h>
+#include <perf/mmap.h>
 #include <internal/mmap.h>
 #include <internal/lib.h>
 #include <linux/kernel.h>
@@ -59,3 +62,32 @@ void perf_mmap__put(struct perf_mmap *map)
 	if (refcount_dec_and_test(&map->refcnt))
 		perf_mmap__munmap(map);
 }
+
+static inline void perf_mmap__write_tail(struct perf_mmap *md, u64 tail)
+{
+	ring_buffer_write_tail(md->base, tail);
+}
+
+u64 perf_mmap__read_head(struct perf_mmap *map)
+{
+	return ring_buffer_read_head(map->base);
+}
+
+static bool perf_mmap__empty(struct perf_mmap *map)
+{
+	struct perf_event_mmap_page *pc = map->base;
+
+	return perf_mmap__read_head(map) == map->prev && !pc->aux_size;
+}
+
+void perf_mmap__consume(struct perf_mmap *map)
+{
+	if (!map->overwrite) {
+		u64 old = map->prev;
+
+		perf_mmap__write_tail(map, old);
+	}
+
+	if (refcount_read(&map->refcnt) == 1 && perf_mmap__empty(map))
+		perf_mmap__put(map);
+}