Only deref a reserved gateway session if we actually reserved one

Its perfectly acceptable to have a gateway session unreserved when we go to
first allocate one.  Unreffing the reserved gateway session - when its NULL -
will result in an assertion error.

This problem was caught by the Asterisk Test Suite (once we had enough of the
debugging flags enabled)
........

Merged revisions 375797 from http://svn.asterisk.org/svn/asterisk/branches/10
........

Merged revisions 375798 from http://svn.asterisk.org/svn/asterisk/branches/11

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@375799 65c4cc65-6c06-0410-ace0-fbb531ad65f3

diff --git a/res/res_fax.c b/res/res_fax.c
index 9cb8292..cc3e23f 100644 (file)
--- a/res/res_fax.c
+++ b/res/res_fax.c
@@ -2583,7 +2583,9 @@ static int fax_gateway_start(struct fax_gateway *gateway, struct ast_fax_session
        }
        /* release the reference for the reserved session and replace it with
         * the real session */
-       ao2_ref(gateway->s, -1);
+       if (gateway->s) {
+               ao2_ref(gateway->s, -1);
+       }
        gateway->s = s;
        gateway->token = NULL;