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Merged revisions 321515 via svnmerge from

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

........
  r321515 | dvossel | 2011-05-31 13:52:54 -0500 (Tue, 31 May 2011) | 12 lines
  
  Chan_local locking cleanup.
  
  This patch removes all of the unnecessary deadlock
  avoidance loops that occur in chan_local.  It also
  resolves an issue with a deadlock triggered by
  local channel optimizations.
  
  (issue #18028)
  
  Review: https://reviewboard.asterisk.org/r/1231/
........


git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@321516 65c4cc65-6c06-0410-ace0-fbb531ad65f3
10-digiumphones
David Vossel 14 years ago
parent 42907d40cd
commit 3588746c75
1 changed files with 280 additions and 213 deletions
Show Stats Download Patch File Download Diff File

493
channels/chan_local.c
Unescape View File

@ -154,68 +154,124 @@ struct local_pvt {
#define LOCAL_BRIDGE (1 << 3) /*!< Report back the "true" channel as being bridged to */
#define LOCAL_MOH_PASSTHRU (1 << 4) /*!< Pass through music on hold start/stop frames */
static int local_setoption(struct ast_channel *chan, int option, void * data, int datalen)
/*
* \brief Send a pvt in with no locks held and get all locks
*
* \note NO locks should be held prior to calling this function
* \note The pvt must have a ref held before calling this function
* \note if outchan or outowner is set != NULL after calling this function
* those channels are locked and reffed.
* \note Batman.
*/
static void awesome_locking(struct local_pvt *p, struct ast_channel **outchan, struct ast_channel **outowner)
{
int res;
struct local_pvt *p;
struct ast_channel *otherchan;
struct ast_channel *chan = NULL;
struct ast_channel *owner = NULL;
for (;;) {
ao2_lock(p);
if (p->chan) {
chan = p->chan;
ast_channel_ref(chan);
}
if (p->owner) {
owner = p->owner;
ast_channel_ref(owner);
}
ao2_unlock(p);
/* if we don't have both channels, then this is very easy */
if (!owner || !chan) {
if (owner) {
ast_channel_lock(owner);
} else if(chan) {
ast_channel_lock(chan);
}
ao2_lock(p);
} else {
/* lock both channels first, then get the pvt lock */
ast_channel_lock(chan);
while (ast_channel_trylock(owner)) {
CHANNEL_DEADLOCK_AVOIDANCE(chan);
}
ao2_lock(p);
}
/* Now that we have all the locks, validate that nothing changed */
if (p->owner != owner || p->chan != chan) {
if (owner) {
ast_channel_unlock(owner);
owner = ast_channel_unref(owner);
}
if (chan) {
ast_channel_unlock(chan);
chan = ast_channel_unref(chan);
}
ao2_unlock(p);
continue;
}
break;
}
*outowner = p->owner;
*outchan = p->chan;
}
static int local_setoption(struct ast_channel *ast, int option, void * data, int datalen)
{
int res = 0;
struct local_pvt *p = NULL;
struct ast_channel *otherchan = NULL;
ast_chan_write_info_t *write_info;
if (option != AST_OPTION_CHANNEL_WRITE) {
return -1;
res = -1;
goto setoption_cleanup;
}
write_info = data;
if (write_info->version != AST_CHAN_WRITE_INFO_T_VERSION) {
ast_log(LOG_ERROR, "The chan_write_info_t type has changed, and this channel hasn't been updated!\n");
return -1;
}
startover:
ast_channel_lock(chan);
p = chan->tech_pvt;
if (!p) {
ast_channel_unlock(chan);
ast_log(LOG_WARNING, "Could not update other side of %s, local_pvt went away.\n", chan->name);
return -1;
res = -1;
goto setoption_cleanup;
}
while (ao2_trylock(p)) {
ast_channel_unlock(chan);
sched_yield();
ast_channel_lock(chan);
p = chan->tech_pvt;
if (!p) {
ast_channel_unlock(chan);
ast_log(LOG_WARNING, "Could not update other side of %s, local_pvt went away.\n", chan->name);
return -1;
}
/* get the tech pvt */
ast_channel_lock(ast);
if (!(p = ast->tech_pvt)) {
ast_channel_unlock(ast);
res = -1;
goto setoption_cleanup;
}
ao2_ref(p, 1);
ast_channel_unlock(ast);
/* get the channel we are supposed to write to */
ao2_lock(p);
otherchan = (write_info->chan == p->owner) ? p->chan : p->owner;
if (!otherchan || otherchan == write_info->chan) {
res = -1;
otherchan = NULL;
ao2_unlock(p);
ast_channel_unlock(chan);
ast_log(LOG_WARNING, "Could not update other side of %s, other side went away.\n", chan->name);
return 0;
goto setoption_cleanup;
}
ast_channel_ref(otherchan);
if (ast_channel_trylock(otherchan)) {
ao2_unlock(p);
ast_channel_unlock(chan);
goto startover;
}
/* clear the pvt lock before grabbing the channel */
ao2_unlock(p);
ast_channel_lock(otherchan);
res = write_info->write_fn(otherchan, write_info->function, write_info->data, write_info->value);
ast_channel_unlock(otherchan);
ao2_unlock(p);
ast_channel_unlock(chan);
setoption_cleanup:
if (p) {
ao2_ref(p, -1);
}
if (otherchan) {
ast_channel_unref(otherchan);
}
return res;
}
@ -294,57 +350,51 @@ static struct ast_channel *local_bridgedchannel(struct ast_channel *chan, struct
static int local_queryoption(struct ast_channel *ast, int option, void *data, int *datalen)
{
struct local_pvt *p = ast->tech_pvt;
struct ast_channel *chan, *bridged;
int res;
struct local_pvt *p;
struct ast_channel *bridged = NULL;
struct ast_channel *tmp = NULL;
int res = 0;
if (!p) {
if (option != AST_OPTION_T38_STATE) {
/* AST_OPTION_T38_STATE is the only supported option at this time */
return -1;
}
if (option != AST_OPTION_T38_STATE) {
/* AST_OPTION_T38_STATE is the only supported option at this time */
/* for some reason the channel is not locked in channel.c when this function is called */
ast_channel_lock(ast);
if (!(p = ast->tech_pvt)) {
ast_channel_unlock(ast);
return -1;
}
ao2_lock(p);
chan = IS_OUTBOUND(ast, p) ? p->owner : p->chan;
try_again:
if (!chan) {
if (!(tmp = IS_OUTBOUND(ast, p) ? p->owner : p->chan)) {
ao2_unlock(p);
ast_channel_unlock(ast);
return -1;
}
ast_channel_ref(tmp);
ao2_unlock(p);
ast_channel_unlock(ast);
if (ast_channel_trylock(chan)) {
ao2_unlock(p);
sched_yield();
ao2_lock(p);
chan = IS_OUTBOUND(ast, p) ? p->owner : p->chan;
goto try_again;
ast_channel_lock(tmp);
if (!(bridged = ast_bridged_channel(tmp))) {
res = -1;
ast_channel_unlock(tmp);
goto query_cleanup;
}
ast_channel_ref(bridged);
ast_channel_unlock(tmp);
bridged = ast_bridged_channel(chan);
if (!bridged) {
/* can't query channel unless we are bridged */
ao2_unlock(p);
ast_channel_unlock(chan);
return -1;
query_cleanup:
if (bridged) {
res = ast_channel_queryoption(bridged, option, data, datalen, 0);
bridged = ast_channel_unref(bridged);
}
if (ast_channel_trylock(bridged)) {
ast_channel_unlock(chan);
ao2_unlock(p);
sched_yield();
ao2_lock(p);
chan = IS_OUTBOUND(ast, p) ? p->owner : p->chan;
goto try_again;
if (tmp) {
tmp = ast_channel_unref(tmp);
}
res = ast_channel_queryoption(bridged, option, data, datalen, 0);
ao2_unlock(p);
ast_channel_unlock(chan);
ast_channel_unlock(bridged);
return res;
}
@ -373,31 +423,24 @@ static int local_queue_frame(struct local_pvt *p, int isoutbound, struct ast_fra
return 0;
}
/* Ensure that we have both channels locked */
while (other && ast_channel_trylock(other)) {
int res;
if ((res = ao2_unlock(p))) {
ast_log(LOG_ERROR, "chan_local bug! '&p->lock' was not locked when entering local_queue_frame! (%s)\n", strerror(res));
return -1;
}
if (us && us_locked) {
do {
CHANNEL_DEADLOCK_AVOIDANCE(us);
} while (ao2_trylock(p));
} else {
usleep(1);
ao2_lock(p);
}
other = isoutbound ? p->owner : p->chan;
/* grab a ref on the channel before unlocking the pvt,
* other can not go away from us now regardless of locking */
ast_channel_ref(other);
if (us && us_locked) {
ast_channel_unlock(us);
}
ao2_unlock(p);
if (other) {
if (f->frametype == AST_FRAME_CONTROL && f->subclass.integer == AST_CONTROL_RINGING) {
ast_setstate(other, AST_STATE_RINGING);
}
ast_queue_frame(other, f);
ast_channel_unlock(other);
if (f->frametype == AST_FRAME_CONTROL && f->subclass.integer == AST_CONTROL_RINGING) {
ast_setstate(other, AST_STATE_RINGING);
}
ast_queue_frame(other, f);
other = ast_channel_unref(other);
if (us && us_locked) {
ast_channel_lock(us);
}
ao2_lock(p);
return 0;
}
@ -429,12 +472,38 @@ static int local_answer(struct ast_channel *ast)
/*!
* \internal
* \note This function assumes that we're only called from the "outbound" local channel side
*
* \note it is assummed p is locked and reffed before entering this function
*/
static void check_bridge(struct local_pvt *p)
{
struct ast_channel_monitor *tmp;
if (ast_test_flag(p, LOCAL_ALREADY_MASQED) || ast_test_flag(p, LOCAL_NO_OPTIMIZATION) || !p->chan || !p->owner || (p->chan->_bridge != ast_bridged_channel(p->chan)))
struct ast_channel *chan = NULL;
struct ast_channel *bridged_chan = NULL;
/* Do a few conditional checks early on just to see if this optimization is possible */
if (ast_test_flag(p, LOCAL_NO_OPTIMIZATION)) {
return;
}
if (ast_test_flag(p, LOCAL_ALREADY_MASQED) || !p->chan || !p->owner) {
return;
}
/* Safely get the channel bridged to p->chan */
chan = ast_channel_ref(p->chan);
ao2_unlock(p); /* don't call bridged channel with the pvt locked */
bridged_chan = ast_bridged_channel(chan);
ao2_lock(p);
chan = ast_channel_unref(chan);
/* since we had to unlock p to get the bridged chan, validate our
* data once again and verify the bridged channel is what we expect
* it to be in order to perform this optimization */
if (ast_test_flag(p, LOCAL_ALREADY_MASQED) || !p->owner || !p->chan || (p->chan->_bridge != bridged_chan)) {
return;
}
/* only do the masquerade if we are being called on the outbound channel,
if it has been bridged to another channel and if there are no pending
@ -521,18 +590,22 @@ static int local_write(struct ast_channel *ast, struct ast_frame *f)
int res = -1;
int isoutbound;
if (!p)
if (!p) {
return -1;
}
/* Just queue for delivery to the other side */
ao2_lock(p);
ao2_ref(p, 1); /* ref for local_queue_frame */
ao2_lock(p);
isoutbound = IS_OUTBOUND(ast, p);
if (isoutbound && f && (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_VIDEO))
if (isoutbound && f && (f->frametype == AST_FRAME_VOICE || f->frametype == AST_FRAME_VIDEO)) {
check_bridge(p);
if (!ast_test_flag(p, LOCAL_ALREADY_MASQED))
}
if (!ast_test_flag(p, LOCAL_ALREADY_MASQED)) {
res = local_queue_frame(p, isoutbound, f, ast, 1);
else {
} else {
ast_debug(1, "Not posting to queue since already masked on '%s'\n", ast->name);
res = 0;
}
@ -731,49 +804,38 @@ static int local_sendhtml(struct ast_channel *ast, int subclass, const char *dat
static int local_call(struct ast_channel *ast, char *dest, int timeout)
{
struct local_pvt *p = ast->tech_pvt;
int pvt_locked = 0;
struct ast_channel *owner = NULL;
struct ast_channel *chan = NULL;
int res;
struct ast_var_t *varptr = NULL, *new;
size_t len, namelen;
char *reduced_dest = ast_strdupa(dest);
char *slash;
struct ast_channel *chan;
const char *exten;
const char *context;
if (!p || p->owner != ast) {
if (!p) {
return -1;
}
/* since we are letting go of channel locks that were locked coming into
* this function, then we need to give the tech pvt a ref */
ao2_ref(p, 1);
ast_channel_unlock(ast);
while (ao2_trylock(p)) {
ast_channel_unlock(ast);
sched_yield();
ast_channel_lock(ast);
}
while ((p->chan && p->owner) && ast_channel_trylock(p->chan)) {
ao2_unlock(p);
if (p->owner) {
ast_channel_unlock(p->owner);
}
sched_yield();
if (p->owner) {
ast_channel_lock(p->owner);
}
ao2_lock(p);
awesome_locking(p, &chan, &owner);
pvt_locked = 1;
if (owner != ast) {
res = -1;
goto return_cleanup;
}
if (!p->owner || !p->chan) {
/* someone went away during the locking madness.
* time to bail. */
if (p->chan) {
ast_channel_unlock(p->chan);
}
ao2_unlock(p);
ao2_ref(p,-1);
return -1;
if (!owner || !chan) {
res = -1;
goto return_cleanup;
}
/*
@ -783,37 +845,37 @@ static int local_call(struct ast_channel *ast, char *dest, int timeout)
* All these failure points just return -1. The individual strings will
* be cleared when we destroy the channel.
*/
ast_party_redirecting_copy(&p->chan->redirecting, &p->owner->redirecting);
ast_party_redirecting_copy(&chan->redirecting, &owner->redirecting);
ast_party_dialed_copy(&p->chan->dialed, &p->owner->dialed);
ast_party_dialed_copy(&chan->dialed, &owner->dialed);
ast_connected_line_copy_to_caller(&p->chan->caller, &p->owner->connected);
ast_connected_line_copy_from_caller(&p->chan->connected, &p->owner->caller);
ast_connected_line_copy_to_caller(&chan->caller, &owner->connected);
ast_connected_line_copy_from_caller(&chan->connected, &owner->caller);
ast_string_field_set(p->chan, language, p->owner->language);
ast_string_field_set(p->chan, accountcode, p->owner->accountcode);
ast_string_field_set(p->chan, musicclass, p->owner->musicclass);
ast_cdr_update(p->chan);
ast_string_field_set(chan, language, owner->language);
ast_string_field_set(chan, accountcode, owner->accountcode);
ast_string_field_set(chan, musicclass, owner->musicclass);
ast_cdr_update(chan);
ast_channel_cc_params_init(p->chan, ast_channel_get_cc_config_params(p->owner));
ast_channel_cc_params_init(chan, ast_channel_get_cc_config_params(owner));
/* Make sure we inherit the ANSWERED_ELSEWHERE flag if it's set on the queue/dial call request in the dialplan */
if (ast_test_flag(ast, AST_FLAG_ANSWERED_ELSEWHERE)) {
ast_set_flag(p->chan, AST_FLAG_ANSWERED_ELSEWHERE);
ast_set_flag(chan, AST_FLAG_ANSWERED_ELSEWHERE);
}
/* copy the channel variables from the incoming channel to the outgoing channel */
/* Note that due to certain assumptions, they MUST be in the same order */
AST_LIST_TRAVERSE(&p->owner->varshead, varptr, entries) {
AST_LIST_TRAVERSE(&owner->varshead, varptr, entries) {
namelen = strlen(varptr->name);
len = sizeof(struct ast_var_t) + namelen + strlen(varptr->value) + 2;
if ((new = ast_calloc(1, len))) {
memcpy(new, varptr, len);
new->value = &(new->name[0]) + namelen + 1;
AST_LIST_INSERT_TAIL(&p->chan->varshead, new, entries);
AST_LIST_INSERT_TAIL(&chan->varshead, new, entries);
}
}
ast_channel_datastore_inherit(p->owner, p->chan);
ast_channel_datastore_inherit(owner, chan);
/* If the local channel has /n or /b on the end of it,
* we need to lop that off for our argument to setting
* up the CC_INTERFACES variable
@ -821,18 +883,21 @@ static int local_call(struct ast_channel *ast, char *dest, int timeout)
if ((slash = strrchr(reduced_dest, '/'))) {
*slash = '\0';
}
ast_set_cc_interfaces_chanvar(p->chan, reduced_dest);
ast_set_cc_interfaces_chanvar(chan, reduced_dest);
chan = ast_channel_ref(p->chan);
ao2_unlock(p);
exten = ast_strdupa(chan->exten);
context = ast_strdupa(chan->context);
ao2_unlock(p);
pvt_locked = 0;
ast_channel_unlock(chan);
if (!ast_exists_extension(chan, context, exten, 1,
S_COR(p->owner->caller.id.number.valid, p->owner->caller.id.number.str, NULL))) {
S_COR(owner->caller.id.number.valid, owner->caller.id.number.str, NULL))) {
ast_log(LOG_NOTICE, "No such extension/context %s@%s while calling Local channel\n", exten, context);
res = -1;
chan = ast_channel_unref(chan); /* we already unlocked it, so clear it hear so the cleanup label won't touch it. */
goto return_cleanup;
}
@ -842,10 +907,33 @@ static int local_call(struct ast_channel *ast, char *dest, int timeout)
ast_set_flag(p, LOCAL_LAUNCHED_PBX);
ao2_unlock(p);
}
chan = ast_channel_unref(chan); /* chan is already unlocked, clear it here so the cleanup lable won't touch it. */
return_cleanup:
ast_channel_unref(chan);
ao2_ref(p, -1);
if (p) {
if (pvt_locked) {
ao2_unlock(p);
}
ao2_ref(p, -1);
}
if (chan) {
ast_channel_unlock(chan);
chan = ast_channel_unref(chan);
}
/* owner is supposed to be == to ast, if it
* is, don't unlock it because ast must exit locked */
if (owner) {
if (owner != ast) {
ast_channel_unlock(owner);
ast_channel_lock(ast);
}
owner = ast_channel_unref(owner);
} else {
/* we have to exit with ast locked */
ast_channel_lock(ast);
}
return res;
}
@ -854,19 +942,31 @@ static int local_hangup(struct ast_channel *ast)
{
struct local_pvt *p = ast->tech_pvt;
int isoutbound;
int hangup_chan = 0;
int res = 0;
struct ast_frame f = { AST_FRAME_CONTROL, { AST_CONTROL_HANGUP }, .data.uint32 = ast->hangupcause };
struct ast_channel *ochan = NULL;
struct ast_channel *owner = NULL;
struct ast_channel *chan = NULL;
if (!p)
if (!p) {
return -1;
}
/* we MUST give the tech_pvt a ref here since we are unlocking the
* channel during deadlock avoidance. */
/* give the pvt a ref since we are unlocking the channel. */
ao2_ref(p, 1);
ao2_lock(p);
/* the pvt isn't going anywhere, we gave it a ref */
ast_channel_unlock(ast);
isoutbound = IS_OUTBOUND(ast, p);
/* lock everything */
awesome_locking(p, &chan, &owner);
if (ast != chan && ast != owner) {
res = -1;
goto local_hangup_cleanup;
}
isoutbound = IS_OUTBOUND(ast, p); /* just comparing pointer of ast */
if (p->chan && ast_test_flag(ast, AST_FLAG_ANSWERED_ELSEWHERE)) {
ast_set_flag(p->chan, AST_FLAG_ANSWERED_ELSEWHERE);
@ -876,92 +976,59 @@ static int local_hangup(struct ast_channel *ast)
if (isoutbound) {
const char *status = pbx_builtin_getvar_helper(p->chan, "DIALSTATUS");
if ((status) && (p->owner)) {
/* Deadlock avoidance */
while (p->owner && ast_channel_trylock(p->owner)) {
ao2_unlock(p);
if (p->chan) {
ast_channel_unlock(p->chan);
}
sched_yield();
if (p->chan) {
ast_channel_lock(p->chan);
}
ao2_lock(p);
}
if (p->owner) {
p->owner->hangupcause = p->chan->hangupcause;
pbx_builtin_setvar_helper(p->owner, "CHANLOCALSTATUS", status);
ast_channel_unlock(p->owner);
}
p->owner->hangupcause = p->chan->hangupcause;
pbx_builtin_setvar_helper(p->owner, "CHANLOCALSTATUS", status);
}
if (!p->chan) {
/* chan was == to ast and was !NULL before deadlock avoidance started, if chan
* is NULL now, then we should bail because that channel
* hungup already. This is possible because we let go of the
* lock given to the ast channel passed to this function during
* deadlock avoidance. */
ao2_unlock(p);
ao2_ref(p, -1);
return 0;
}
p->chan = NULL;
ast_clear_flag(p, LOCAL_LAUNCHED_PBX);
ast_module_user_remove(p->u_chan);
p->chan = NULL;
} else {
ast_module_user_remove(p->u_owner);
while (p->chan && ast_channel_trylock(p->chan)) {
ao2_unlock(p);
if (p->owner) {
ast_channel_unlock(p->owner);
}
sched_yield();
if (p->owner) {
ast_channel_lock(p->owner);
}
ao2_lock(p);
}
if (p->chan) {
ast_queue_hangup(p->chan);
ast_channel_unlock(p->chan);
}
if (!p->owner) {
/* owner was == to ast and was !NULL before deadlock avoidance started, if
* owner is NULL now, then we should bail because that channel
* hungup already. This is possible because we let go of the
* lock given to the ast channel passed to this function during
* deadlock avoidance. */
ao2_unlock(p);
ao2_ref(p, -1);
return 0;
}
p->owner = NULL;
}
ast->tech_pvt = NULL;
ast->tech_pvt = NULL; /* this is one of our locked channels, doesn't matter which */
if (!p->owner && !p->chan) {
ao2_unlock(p);
/* Remove from list */
ao2_unlink(locals, p);
ao2_ref(p, -1);
return 0;
p = NULL;
res = 0;
goto local_hangup_cleanup;
}
if (p->chan && !ast_test_flag(p, LOCAL_LAUNCHED_PBX)) {
/* Need to actually hangup since there is no PBX */
ochan = p->chan;
hangup_chan = 1;
} else {
local_queue_frame(p, isoutbound, &f, NULL, 1);
local_queue_frame(p, isoutbound, &f, NULL, 0);
}
ao2_unlock(p);
if (ochan) {
ast_hangup(ochan);
local_hangup_cleanup:
if (p) {
ao2_unlock(p);
ao2_ref(p, -1);
}
if (chan) {
ast_channel_unlock(chan);
if (hangup_chan) {
ast_hangup(chan);
}
chan = ast_channel_unref(chan);
}
if (owner) {
ast_channel_unlock(owner);
owner = ast_channel_unref(owner);
}
ao2_ref(p, -1);
return 0;
/* leave with the same stupid channel locked that came in */
ast_channel_lock(ast);
return res;
}
static void local_destroy(void *obj)

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