perf evlist: Map backward events to backward_mmap

In perf_evlist__mmap_per_evsel(), select backward_mmap for backward
events. Utilize new perf_mmap APIs. Dynamically alloc backward_mmap.

Remove useless functions.

Signed-off-by: Wang Nan <[e-mail]>
Acked-by: Jiri Olsa <[e-mail]>
Cc: He Kuang <[e-mail]>
Cc: Masami Hiramatsu <[e-mail]>
Cc: Namhyung Kim <[e-mail]>
Cc: Nilay Vaish <[e-mail]>
Cc: Zefan Li <[e-mail]>
Cc: [e-mail]
Link: http://lkml.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/perf/tests/backward-ring-buffer.c

···
 	for (i = 0; i < evlist->nr_mmaps; i++) {
 		union perf_event *event;
 
-		perf_evlist__mmap_read_catchup(evlist, i);
-		while ((event = perf_evlist__mmap_read_backward(evlist, i)) != NULL) {
+		perf_mmap__read_catchup(&evlist->backward_mmap[i]);
+		while ((event = perf_mmap__read_backward(&evlist->backward_mmap[i])) != NULL) {
 			const u32 type = event->header.type;
 
 			switch (type) {

tools/perf/util/evlist.c

···
 #include <linux/log2.h>
 #include <linux/err.h>
 
-static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx);
 static void perf_mmap__munmap(struct perf_mmap *map);
 static void perf_mmap__put(struct perf_mmap *map);
 
···
 {
 	int i;
 
+	if (!evlist->backward_mmap)
+		return 0;
+
 	for (i = 0; i < evlist->nr_mmaps; i++) {
-		int fd = evlist->mmap[i].fd;
+		int fd = evlist->backward_mmap[i].fd;
 		int err;
 
 		if (fd < 0)
···
 		perf_mmap__munmap(md);
 }
 
-static void perf_evlist__mmap_get(struct perf_evlist *evlist, int idx)
-{
-	perf_mmap__get(&evlist->mmap[idx]);
-}
-
-static void perf_evlist__mmap_put(struct perf_evlist *evlist, int idx)
-{
-	perf_mmap__put(&evlist->mmap[idx]);
-}
-
 void perf_mmap__consume(struct perf_mmap *md, bool overwrite)
 {
 	if (!overwrite) {
···
 	return 0;
 }
 
-static int __perf_evlist__mmap(struct perf_evlist *evlist, int idx,
-			       struct mmap_params *mp, int fd)
-{
-	return perf_mmap__mmap(&evlist->mmap[idx], mp, fd);
-}
-
 static bool
 perf_evlist__should_poll(struct perf_evlist *evlist __maybe_unused,
 			 struct perf_evsel *evsel)
···
 
 static int perf_evlist__mmap_per_evsel(struct perf_evlist *evlist, int idx,
 				       struct mmap_params *mp, int cpu,
-				       int thread, int *output)
+				       int thread, int *_output, int *_output_backward)
 {
 	struct perf_evsel *evsel;
 	int revent;
 
 	evlist__for_each_entry(evlist, evsel) {
+		struct perf_mmap *maps = evlist->mmap;
+		int *output = _output;
 		int fd;
 
-		if (!!evsel->attr.write_backward != (evlist->overwrite && evlist->backward))
-			continue;
+		if (evsel->attr.write_backward) {
+			output = _output_backward;
+			maps = evlist->backward_mmap;
+
+			if (!maps) {
+				maps = perf_evlist__alloc_mmap(evlist);
+				if (!maps)
+					return -1;
+				evlist->backward_mmap = maps;
+			}
+		}
 
 		if (evsel->system_wide && thread)
 			continue;
···
 
 		if (*output == -1) {
 			*output = fd;
-			if (__perf_evlist__mmap(evlist, idx, mp, *output) < 0)
+
+			if (perf_mmap__mmap(&maps[idx], mp, *output)  < 0)
 				return -1;
 		} else {
 			if (ioctl(fd, PERF_EVENT_IOC_SET_OUTPUT, *output) != 0)
 				return -1;
 
-			perf_evlist__mmap_get(evlist, idx);
+			perf_mmap__get(&maps[idx]);
 		}
 
 		revent = perf_evlist__should_poll(evlist, evsel) ? POLLIN : 0;
···
 		 * Therefore don't add it for polling.
 		 */
 		if (!evsel->system_wide &&
-		    __perf_evlist__add_pollfd(evlist, fd, &evlist->mmap[idx], revent) < 0) {
-			perf_evlist__mmap_put(evlist, idx);
+		    __perf_evlist__add_pollfd(evlist, fd, &maps[idx], revent) < 0) {
+			perf_mmap__put(&maps[idx]);
 			return -1;
 		}
 
···
 	pr_debug2("perf event ring buffer mmapped per cpu\n");
 	for (cpu = 0; cpu < nr_cpus; cpu++) {
 		int output = -1;
+		int output_backward = -1;
 
 		auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, cpu,
 					      true);
 
 		for (thread = 0; thread < nr_threads; thread++) {
 			if (perf_evlist__mmap_per_evsel(evlist, cpu, mp, cpu,
-							thread, &output))
+							thread, &output, &output_backward))
 				goto out_unmap;
 		}
 	}
···
 	pr_debug2("perf event ring buffer mmapped per thread\n");
 	for (thread = 0; thread < nr_threads; thread++) {
 		int output = -1;
+		int output_backward = -1;
 
 		auxtrace_mmap_params__set_idx(&mp->auxtrace_mp, evlist, thread,
 					      false);
 
 		if (perf_evlist__mmap_per_evsel(evlist, thread, mp, 0, thread,
-						&output))
+						&output, &output_backward))
 			goto out_unmap;
 	}