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Fix deadlock if peer is destroyed while sending MWI notice.

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A dialog cannot be destroyed by the ao2_callback dialog_needdestroy
because of a deadlock between the dialogs container lock and the RWLOCK of
the events subscription list.

* Create dialogs_to_destroy container to hold dialogs that will be
destroyed.

* Ensure that the event subscription callback will never happen with an
invalid peer pointer by making the event callback removal the first thing
in the peer destructor callback.

NOTE: This particular deadlock will not happen with Asterisk 10, but some
of the changes still apply.

(closes issue ASTERISK-18747)
Reported by: Gregory Hinton Nietsky

Review: https://reviewboard.asterisk.org/r/1564/
........

Merged revisions 343577 from http://svn.asterisk.org/svn/asterisk/branches/1.8
........

Merged revisions 343578 from http://svn.asterisk.org/svn/asterisk/branches/10


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@343579 65c4cc65-6c06-0410-ace0-fbb531ad65f3
This commit is contained in:
Richard Mudgett
2011-11-07 19:54:09 +00:00
parent f3c03ac1ec
commit 7a5f6684f0
1 changed files with 19 additions and 6 deletions
Download Patch File Download Diff File Expand all files Collapse all files

23
channels/chan_sip.c
View File

@@ -2956,6 +2956,13 @@ static void *dialog_unlink_rtpcheck(struct sip_pvt *dialog)
return NULL;
}
/*!
* \brief Unlink a dialog from the dialogs container, as well as any other places
* that it may be currently stored.
*
* \note A reference to the dialog must be held before calling this function, and this
* function does not release that reference.
*/
void dialog_unlink_all(struct sip_pvt *dialog)
{
struct sip_pkt *cp;
@@ -4589,9 +4596,18 @@ static void sip_destroy_peer_fn(void *peer)
static void sip_destroy_peer(struct sip_peer *peer)
{
ast_debug(3, "Destroying SIP peer %s\n", peer->name);
if (peer->outboundproxy)
/*
* Remove any mailbox event subscriptions for this peer before
* we destroy anything. An event subscription callback may be
* happening right now.
*/
clear_peer_mailboxes(peer);
if (peer->outboundproxy) {
ao2_ref(peer->outboundproxy, -1);
peer->outboundproxy = NULL;
}
/* Delete it, it needs to disappear */
if (peer->call) {
@@ -4625,7 +4641,6 @@ static void sip_destroy_peer(struct sip_peer *peer)
}
if (peer->dnsmgr)
ast_dnsmgr_release(peer->dnsmgr);
clear_peer_mailboxes(peer);
if (peer->socket.tcptls_session) {
ao2_ref(peer->socket.tcptls_session, -1);
@@ -17045,14 +17060,12 @@ static int dialog_checkrtp_cb(void *dialogobj, void *arg, int flags)
* \brief Match dialogs that need to be destroyed
*
* \details This is used with ao2_callback to unlink/delete all dialogs that
* are marked needdestroy. It will return CMP_MATCH for candidates, and they
* will be unlinked.
* are marked needdestroy.
*
* \todo Re-work this to improve efficiency. Currently, this function is called
* on _every_ dialog after processing _every_ incoming SIP/UDP packet, or
* potentially even more often when the scheduler has entries to run.
*/
static int dialog_needdestroy(void *dialogobj, void *arg, int flags)
{
struct sip_pvt *dialog = dialogobj;