core: Add cache_media_frames debugging option.

The media frame cache gets in the way of finding use after free errors of
media frames.  Tools like valgrind and MALLOC_DEBUG don't know when a
frame is released because it gets put into the cache instead of being
freed.

* Added the "cache_media_frames" option to asterisk.conf.  Disabling the
option helps track down media frame mismanagement when using valgrind or
MALLOC_DEBUG.  The cache gets in the way of determining if the frame is
used after free and who freed it.  NOTE: This option has no effect when
Asterisk is compiled with the LOW_MEMORY compile time option enabled
because the cache code does not exist.

To disable the media frame cache simply disable the cache_media_frames
option in asterisk.conf and restart Asterisk.

Sample asterisk.conf setting:
[options]
cache_media_frames=no

ASTERISK-27413

Change-Id: I0ab2ce0f4547cccf2eb214901835c2d951b78c00

2 files changed, 20 insertions, 7 deletions

diff --git a/main/asterisk.c b/main/asterisk.c
index 40986a484..20ed947f7 100644
--- a/main/asterisk.c
+++ b/main/asterisk.c
@@ -607,6 +607,9 @@ static char *handle_show_settings(struct ast_cli_entry *e, int cmd, struct ast_c
 	ast_cli(a->fd, "  Transmit silence during rec: %s\n", ast_test_flag(&ast_options, AST_OPT_FLAG_TRANSMIT_SILENCE) ? "Enabled" : "Disabled");
 	ast_cli(a->fd, "  Generic PLC:                 %s\n", ast_test_flag(&ast_options, AST_OPT_FLAG_GENERIC_PLC) ? "Enabled" : "Disabled");
 	ast_cli(a->fd, "  Min DTMF duration::          %u\n", option_dtmfminduration);
+#if !defined(LOW_MEMORY)
+	ast_cli(a->fd, "  Cache media frames:          %s\n", ast_opt_cache_media_frames ? "Enabled" : "Disabled");
+#endif
 	ast_cli(a->fd, "  RTP use dynamic payloads:    %u\n", ast_option_rtpusedynamic);
 
 	if (ast_option_rtpptdynamic == AST_RTP_PT_LAST_REASSIGN) {
@@ -3714,6 +3717,11 @@ static void ast_readconfig(void)
 		/* Cache recorded sound files to another directory during recording */
 		} else if (!strcasecmp(v->name, "cache_record_files")) {
 			ast_set2_flag(&ast_options, ast_true(v->value), AST_OPT_FLAG_CACHE_RECORD_FILES);
+#if !defined(LOW_MEMORY)
+		/* Cache media frames for performance */
+		} else if (!strcasecmp(v->name, "cache_media_frames")) {
+			ast_set2_flag(&ast_options, ast_true(v->value), AST_OPT_FLAG_CACHE_MEDIA_FRAMES);
+#endif
 		/* Specify cache directory */
 		}  else if (!strcasecmp(v->name, "record_cache_dir")) {
 			ast_copy_string(record_cache_dir, v->value, AST_CACHE_DIR_LEN);
diff --git a/main/frame.c b/main/frame.c
index c24cc8f78..690d48e27 100644
--- a/main/frame.c
+++ b/main/frame.c
@@ -120,14 +120,18 @@ static void __frame_free(struct ast_frame *fr, int cache)
 		return;
 
 #if !defined(LOW_MEMORY)
-	if (cache && fr->mallocd == AST_MALLOCD_HDR) {
+	if (fr->mallocd == AST_MALLOCD_HDR
+		&& cache
+		&& ast_opt_cache_media_frames) {
 		/* Cool, only the header is malloc'd, let's just cache those for now
 		 * to keep things simple... */
 		struct ast_frame_cache *frames;
-		if ((frames = ast_threadstorage_get(&frame_cache, sizeof(*frames))) &&
-		    (frames->size < FRAME_CACHE_MAX_SIZE)) {
-			if ((fr->frametype == AST_FRAME_VOICE) || (fr->frametype == AST_FRAME_VIDEO) ||
-				(fr->frametype == AST_FRAME_IMAGE)) {
+
+		frames = ast_threadstorage_get(&frame_cache, sizeof(*frames));
+		if (frames && frames->size < FRAME_CACHE_MAX_SIZE) {
+			if (fr->frametype == AST_FRAME_VOICE
+				|| fr->frametype == AST_FRAME_VIDEO
+				|| fr->frametype == AST_FRAME_IMAGE) {
 				ao2_cleanup(fr->subclass.format);
 			}
 
@@ -147,8 +151,9 @@ static void __frame_free(struct ast_frame *fr, int cache)
 		ast_free((void *) fr->src);
 	}
 	if (fr->mallocd & AST_MALLOCD_HDR) {
-		if ((fr->frametype == AST_FRAME_VOICE) || (fr->frametype == AST_FRAME_VIDEO) ||
-			(fr->frametype == AST_FRAME_IMAGE)) {
+		if (fr->frametype == AST_FRAME_VOICE
+			|| fr->frametype == AST_FRAME_VIDEO
+			|| fr->frametype == AST_FRAME_IMAGE) {
 			ao2_cleanup(fr->subclass.format);
 		}