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Merged revisions 301790 via svnmerge from 

https://origsvn.digium.com/svn/asterisk/branches/1.8

........
  r301790 | jpeeler | 2011-01-14 11:32:52 -0600 (Fri, 14 Jan 2011) | 42 lines
  
  Resolve deadlock involving REFER.
  
  Two fixes:
  1) One must always have the private unlocked before calling
  pbx_builtin_setvar_helper to not invalidate locking order since it locks the
  channel.
  2) Unlock the channel before calling pbx_find_extension, which starts and stops
  autoservice during the lookup. The problem scenario as illustrated by the
  reporter:
  
  Thread: do_monitor
  -----------------------
  handle_request_do
   handle_incoming
    handle_request_refer
     ast_parking_ext_valid
      pbx_find_extension
       ast_autoservice_stop
        while (chan_list_state == as_chan_list_state) { usleep(1000); }
  
  Thread: autoservice_run
  -----------------------
  autoservice_run
   chan = ast_waitfor_n
    ast_waitfor_nandfds
     ast_waitfor_nandfds_classic / simple / complex (depending on your system)
      ast_channel_lock(c[x]);
  
  handle_request_do and schedule_process_request_queue locks the owner
  if it exists. The autoservice thread is waiting for the channel lock, which
  wasn't ever released since the do_monitor thread was waiting for autoservice
  operations to complete. Solved by unlocking the channel but keeping a reference
  to guarantee safety.
  
  (closes issue #18403)
  Reported by: jthurman
  Patches: 
        20110103-blind_deadlock.diff uploaded by jthurman (license 614)
        issue18403.patch uploaded by jpeeler (license 325)
  Tested by: jthurman
........


git-svn-id: http://svn.digium.com/svn/asterisk/trunk@301791 f38db490-d61c-443f-a65b-d21fe96a405b
This commit is contained in:
jpeeler 2011-01-14 17:34:28 +00:00
parent b2273c22ea
commit 3a449d1a53
1 changed files with 16 additions and 12 deletions
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28
channels/chan_sip.c
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@ -22353,11 +22353,20 @@ static int handle_request_refer(struct sip_pvt *p, struct sip_request *req, int
/* Fallthrough if we can't find the call leg internally */
}
/* Must release lock now, because it will not longer
be accessible after the transfer! */
*nounlock = 1;
/*
* Increase ref count so that we can delay channel destruction until after
* we get a chance to fire off some events.
*/
ast_channel_ref(current.chan1);
sip_pvt_unlock(p);
ast_channel_unlock(current.chan1);
/* Parking a call */
if (p->refer->localtransfer && ast_parking_ext_valid(p->refer->refer_to, p->owner, p->owner->context)) {
/* Must release c's lock now, because it will not longer be accessible after the transfer! */
*nounlock = 1;
ast_channel_unlock(current.chan1);
sip_pvt_lock(p);
copy_request(&current.req, req);
ast_clear_flag(&p->flags[0], SIP_GOTREFER);
p->refer->status = REFER_200OK;
@ -22383,6 +22392,7 @@ static int handle_request_refer(struct sip_pvt *p, struct sip_request *req, int
if (sip_park(current.chan2, current.chan1, req, seqno, p->refer->refer_to)) {
transmit_notify_with_sipfrag(p, seqno, "500 Internal Server Error", TRUE);
}
ast_channel_unref(current.chan1);
return res;
}
@ -22391,6 +22401,9 @@ static int handle_request_refer(struct sip_pvt *p, struct sip_request *req, int
ast_debug(3, "chan1->name: %s\n", current.chan1->name);
pbx_builtin_setvar_helper(current.chan1, "BLINDTRANSFER", current.chan2->name);
}
sip_pvt_lock(p);
if (current.chan2) {
pbx_builtin_setvar_helper(current.chan2, "BLINDTRANSFER", current.chan1->name);
pbx_builtin_setvar_helper(current.chan2, "SIPDOMAIN", p->refer->refer_to_domain);
@ -22412,15 +22425,6 @@ static int handle_request_refer(struct sip_pvt *p, struct sip_request *req, int
if (current.chan2)
pbx_builtin_setvar_helper(current.chan2, "_SIPTRANSFER_REPLACES", tempheader);
}
/* Must release lock now, because it will not longer
be accessible after the transfer! */
*nounlock = 1;
/*
* Increase ref count so that we can delay channel destruction until after
* we get a chance to fire off some events.
*/
ast_channel_ref(current.chan1);
ast_channel_unlock(current.chan1);
/* Connect the call */