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avoid deadlock when holding callback lock, deleting channel, but not

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identified as thread that might be in possesion of cb lock
This commit is contained in:
Jeff Hill
2002-02-11 19:22:17 +00:00
parent 94835992fc
commit bb307159d9
1 changed files with 60 additions and 44 deletions
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104
src/ca/cac.cpp
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@@ -286,7 +286,7 @@ cac::~cac ()
// wait for tcp threads to exit
//
while ( this->serverTable.numEntriesInstalled() ) {
this->iiuUninstal.wait ();
this->iiuUninstall.wait ();
}
delete this->pRepeaterSubscribeTmr;
@@ -440,7 +440,8 @@ void cac::show ( unsigned level ) const
/*
* cac::beaconNotify
*/
void cac::beaconNotify ( const inetAddrID & addr, const epicsTime & currentTime )
void cac::beaconNotify ( const inetAddrID & addr, const epicsTime & currentTime,
unsigned beaconNumber, unsigned protocolRevision )
{
epicsAutoMutex autoMutex ( this->mutex );
@@ -456,7 +457,8 @@ void cac::beaconNotify ( const inetAddrID & addr, const epicsTime & currentTime
/*
* return if the beacon period has not changed significantly
*/
if ( ! pBHE->updatePeriod ( this->programBeginTime, currentTime ) ) {
if ( ! pBHE->updatePeriod ( this->programBeginTime, currentTime,
beaconNumber, protocolRevision ) ) {
return;
}
}
@@ -877,56 +879,70 @@ bool cac::lookupChannelAndTransferToTCP ( unsigned cid, unsigned sid,
void cac::uninstallChannel ( nciu & chan )
{
// wait for any IO callbacks in progress to complete
// prior to destroying the IO object
tsDLList < baseNMIU > tmpList;
// uninstall channel and any subsiderary IO so that recv threads
// will not start a new callback for this channel's IO. Send any
// side effect IO requests w/o holding the callback lock so that
// we do not dead lock
{
epicsAutoMutex autoMutex ( this->mutex );
this->flushIfRequired ( *chan.getPIIU() );
while ( baseNMIU *pIO = chan.cacPrivateListOfIO::eventq.get() ) {
tmpList.add ( *pIO );
this->ioTable.remove ( *pIO );
class netSubscription *pSubscr = pIO->isSubscription ();
if ( pSubscr && chan.connected() ) {
chan.getPIIU()->subscriptionCancelRequest ( chan, *pSubscr );
}
{
epicsAutoMutexRelease autoMutexRelease ( this->mutex );
// If they call ioCancel() here it will be ignored
// because the IO has been unregistered above
pIO->exception ( ECA_CHANDESTROY, chan.pName() );
}
}
nciu * pChan = this->chanTable.remove ( chan );
assert ( pChan == &chan );
// if the claim reply has not returned yet then we will issue
// the clear channel request to the server when the claim reply
// arrives and there is no matching nciu in the client
if ( pChan->connected() ) {
chan.getPIIU()->clearChannelRequest ( chan.getSID(), chan.getCID() );
}
chan.getPIIU()->detachChannel ( chan );
}
// take callback lock briefly to ensure that any callbacks in
// progress complete prior to destroying channel and any associated IO
//
// If this is a callback thread then it already owns the
// CB lock at this point. If this is the main thread then we
// are not in pendEvent, pendIO, SG block, etc and
// this->pCallbackLocker protects. Otherwise if this is
// the users auxillary thread then this->pCallbackLocker
// a preemptive callback enabled app then this->pCallbackLocker
// isnt set and we must take the call back lock.
if ( epicsThreadPrivateGet ( caClientCallbackThreadId ) ) {
this->uninstallChannelPrivate ( chan );
}
else if ( this->pCallbackLocker ) {
this->uninstallChannelPrivate ( chan );
}
else {
// taking this mutex guarantees that we will not delete
// a channel out from under a callback
//
// must _not_ hold callback lock while sending channel and subscription
// cancel requests above unless.
// 1) this is a recv thread
// 2) this is the thread that initialized the library and preemptive
// callback is disabled
bool alreadyLocked = epicsThreadPrivateGet ( caClientCallbackThreadId )
|| this->pCallbackLocker;
if ( ! alreadyLocked ) {
// taking this mutex priior to deleting the IO and channel guarantees
// that we will not delete a channel out from under a callback
epicsAutoMutex autoCallbackMutex ( this->callbackMutex );
this->uninstallChannelPrivate ( chan );
}
}
void cac::uninstallChannelPrivate ( nciu & chan )
{
epicsAutoMutex autoMutex ( this->mutex );
this->flushIfRequired ( *chan.getPIIU() );
while ( baseNMIU *pIO = chan.cacPrivateListOfIO::eventq.get() ) {
this->ioTable.remove ( *pIO );
class netSubscription *pSubscr = pIO->isSubscription ();
if ( pSubscr && chan.connected() ) {
chan.getPIIU()->subscriptionCancelRequest ( chan, *pSubscr );
}
{
epicsAutoMutexRelease autoMutexRelease ( this->mutex );
// If they call ioCancel() here it will be ignored
// because the IO has been unregistered above
pIO->exception ( ECA_CHANDESTROY, chan.pName() );
}
pIO->destroy ( *this );
}
nciu * pChan = this->chanTable.remove ( chan );
assert ( pChan = &chan );
// if the claim reply has not returned yet then we will issue
// the clear channel request to the server when the claim reply
// arrives and there is no matching nciu in the client
if ( pChan->connected() ) {
chan.getPIIU()->clearChannelRequest ( chan.getSID(), chan.getCID() );
// destroy subsiderary IO now that it is safe to do so
{
epicsAutoMutex autoMutex ( this->mutex );
while ( baseNMIU *pIO = tmpList.get() ) {
pIO->destroy ( *this );
}
}
chan.getPIIU()->detachChannel ( chan );
}
int cac::printf ( const char *pformat, ... ) const
@@ -1834,7 +1850,7 @@ void cac::privateUninstallIIU ( tcpiiu & iiu )
this->pSearchTmr->resetPeriod ( 0.0 );
// signal iiu uninstal event so that cac can properly shut down
this->iiuUninstal.signal();
this->iiuUninstall.signal();
}
void cac::preemptiveCallbackLock ()