res_fax.c: Remove redundant locking.

When FAX was developed, apparently the faxregistry.container used to be a
linked list that was converted to an ao2 container.  Some of the
replacement ao2 container operations still had explicit lock/unlocks
around them.

Two off nominal code paths in res_fax.c unlock the channel even though the
routine did not lock the channel and other code paths in the routine do
not unlock the channel.

Review: https://reviewboard.asterisk.org/r/4340/

Backported from v13 revision fa80d9658df8aff71a8975ab7d1fe477ea3f99b9.

Change-Id: I59a1b95a91dac8375e0db568ddb217bcd6d7d2fa

diff --git a/res/res_fax.c b/res/res_fax.c
index f4deca4e05229963558cab1296dbfddaacb13896..5f660fe78d9a4a2b71d65b3431459172dc160af2 100644 (file)
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -1370,21 +1370,15 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
                ast_format_copy(&orig_write_format, ast_channel_writeformat(chan));
                if (ast_set_write_format_by_id(chan, AST_FORMAT_SLINEAR) < 0) {
                        ast_log(LOG_ERROR, "channel '%s' failed to set write format to signed linear'.\n", ast_channel_name(chan));
-                       ao2_lock(faxregistry.container);
-                       ao2_unlink(faxregistry.container, fax);
-                       ao2_unlock(faxregistry.container);
-                       ao2_ref(fax, -1);
-                       ast_channel_unlock(chan);
+                       ao2_unlink(faxregistry.container, fax);
+                       ao2_ref(fax, -1);
                        return -1;
                }
                ast_format_copy(&orig_read_format, ast_channel_readformat(chan));
                if (ast_set_read_format_by_id(chan, AST_FORMAT_SLINEAR) < 0) {
                        ast_log(LOG_ERROR, "channel '%s' failed to set read format to signed linear.\n", ast_channel_name(chan));
-                       ao2_lock(faxregistry.container);
-                       ao2_unlink(faxregistry.container, fax);
-                       ao2_unlock(faxregistry.container);
-                       ao2_ref(fax, -1);
-                       ast_channel_unlock(chan);
+                       ao2_unlink(faxregistry.container, fax);
+                       ao2_ref(fax, -1);
                        return -1;
                }
                if (fax->smoother) {
@@ -1560,9 +1554,7 @@ static int generic_fax_exec(struct ast_channel *chan, struct ast_fax_session_det
        }
 
        if (fax) {
-               ao2_lock(faxregistry.container);
                ao2_unlink(faxregistry.container, fax);
-               ao2_unlock(faxregistry.container);
                ao2_ref(fax, -1);
        }
 
@@ -2508,18 +2500,14 @@ static int sendfax_exec(struct ast_channel *chan, const char *data)
 static void destroy_v21_sessions(struct fax_gateway *gateway)
 {
        if (gateway->chan_v21_session) {
-               ao2_lock(faxregistry.container);
                ao2_unlink(faxregistry.container, gateway->chan_v21_session);
-               ao2_unlock(faxregistry.container);
 
                ao2_ref(gateway->chan_v21_session, -1);
                gateway->chan_v21_session = NULL;
        }
 
        if (gateway->peer_v21_session) {
-               ao2_lock(faxregistry.container);
                ao2_unlink(faxregistry.container, gateway->peer_v21_session);
-               ao2_unlock(faxregistry.container);
 
                ao2_ref(gateway->peer_v21_session, -1);
                gateway->peer_v21_session = NULL;
@@ -2537,9 +2525,7 @@ static void destroy_gateway(void *data)
                fax_session_release(gateway->s, gateway->token);
                gateway->token = NULL;
 
-               ao2_lock(faxregistry.container);
                ao2_unlink(faxregistry.container, gateway->s);
-               ao2_unlock(faxregistry.container);
 
                ao2_ref(gateway->s, -1);
                gateway->s = NULL;