Skip to content

Commit

Permalink
MB-35049: Release StreamContainer rlock before calling Stream::setDead
Browse files Browse the repository at this point in the history 
TSan found lock inversion as DcpProducer::setDisconnect holds
`StreamContainer->rlock()` and then acquires `vb->getStateLock()`
whereas `VBucket::set()` acquires them in the opposite order.

Release the stream container lock before calling `Stream::setDead()` to
avoid holding both in the `setDisconnect` path.

TSan report:

 [ RUN      ] DurabilityTest.MB34780
 ==================
 WARNING: ThreadSanitizer: lock-order-inversion (potential deadlock) (pid=10424)
   Cycle in lock order graph: M4054 (0x7b68000308f8) => M201671426334441480 (0x000000000000) => M4054

   Mutex M201671426334441480 acquired here while holding mutex M4054 in thread T7:
     #0 pthread_rwlock_rdlock <null> (libtsan.so.0+0x00000002953b)
     #1 cb_rw_reader_enter(pthread_rwlock_t*) .../platform/src/cb_pthreads.cc:195 (libplatform_so.so.0.1.0+0x000000009cfa)
     #2 cb::RWLock::readerLock() .../platform/include/platform/rwlock.h:87 (ep.so+0x0000000f4326)
     #3 cb::RWLock::lock_shared() .../platform/include/platform/rwlock.h:67 (ep.so+0x00000012f2ba)
     #4 std::shared_lock<cb::RWLock>::shared_lock(cb::RWLock&) /usr/local/include/c++/7.3.0/shared_mutex:553 (ep.so+0x00000012f2ba)
     #5 StreamContainer<std::shared_ptr<Stream> >::ReadLockedHandle::ReadLockedHandle(...) .../kv_engine/engines/ep/src/dcp/stream_container.h:213 (ep.so+0x00000012f2ba)
     #6 StreamContainer<std::shared_ptr<Stream> >::rlock() const .../kv_engine/engines/ep/src/dcp/stream_container.h:273 (ep.so+0x000000122ad5)
     #7 DcpProducer::notifySeqnoAvailable(Vbid, unsigned long) .../kv_engine/engines/ep/src/dcp/producer.cc:1312 (ep.so+0x000000122ad5)
     #8 DcpConnMap::notifyVBConnections(Vbid, unsigned long) .../kv_engine/engines/ep/src/dcp/dcpconnmap.cc:424 (ep.so+0x0000000fa0af)
     #9 KVBucket::notifyReplication(Vbid, long) .../kv_engine/engines/ep/src/kv_bucket.cc:2570 (ep.so+0x00000020ed03)
     #10 EPBucket::notifyNewSeqno(Vbid, VBNotifyCtx const&) .../kv_engine/engines/ep/src/ep_bucket.cc:1327 (ep.so+0x000000160a95)
     #11 NotifyNewSeqnoCB::callback(Vbid const&, VBNotifyCtx const&) .../kv_engine/engines/ep/src/kv_bucket.h:837 (ep.so+0x000000224dcb)
     #12 VBucket::notifyNewSeqno(VBNotifyCtx const&) .../kv_engine/engines/ep/src/vbucket.cc:3579 (ep.so+0x000000262f6b)
     #13 VBucket::set(...) .../kv_engine/engines/ep/src/vbucket.cc:1569 (ep.so+0x00000026af3f)
     #14 KVBucket::set(...) .../kv_engine/engines/ep/src/kv_bucket.cc:692 (ep.so+0x00000021ee48)
     #15 EventuallyPersistentEngine::storeIfInner(...) .../kv_engine/engines/ep/src/ep_engine.cc:2440 (ep.so+0x00000018071f)

   Mutex M4054 previously acquired by the same thread here:
     #0 AnnotateRWLockAcquired <null> (libtsan.so.0+0x00000005b63d)
     #1 folly::detail::annotate_rwlock_acquired_impl(...) .../follytsan/folly/synchronization/SanitizeThread.cpp:91 (memcached+0x0000006463de)
     #2 annotate_rwlock_acquired .../build/tlm/deps/folly.exploded/include/folly/synchronization/SanitizeThread.h:99 (ep.so+0x00000021e932)
     #3 folly::SharedMutexImpl<false, void, std::atomic, false, true>::annotateAcquired(folly::annotate_rwlock_level) .../build/tlm/deps/folly.exploded/include/folly/SharedMutex.h:696 (ep.so+0x00000021e932)
     #4 folly::SharedMutexImpl<false, void, std::atomic, false, true>::lock_shared(folly::SharedMutexToken&) .../build/tlm/deps/folly.exploded/include/folly/SharedMutex.h:376 (ep.so+0x00000021e932)
     #5 folly::SharedMutexImpl<false, void, std::atomic, false, true>::ReadHolder::ReadHolder(folly::SharedMutexImpl<false, void, std::atomic, false, true> const&) .../build/tlm/deps/folly.exploded/include/folly/SharedMutex.h:1315 (ep.so+0x00000021e932)
     #6 KVBucket::set(...) .../kv_engine/engines/ep/src/kv_bucket.cc:659 (ep.so+0x00000021e932)
     #7 EventuallyPersistentEngine::storeIfInner(...)> const&) .../kv_engine/engines/ep/src/ep_engine.cc:2440 (ep.so+0x00000018071f)

   Mutex M4054 acquired here while holding mutex M201671426334441480 in thread T5:
     #0 AnnotateRWLockAcquired <null> (libtsan.so.0+0x00000005b63d)
     #1 folly::detail::annotate_rwlock_acquired_impl(void const volatile*, folly::annotate_rwlock_level, char const*, int) .../follytsan/folly/synchronization/SanitizeThread.cpp:91 (memcached+0x0000006463de)
     #2 annotate_rwlock_acquired .../build/tlm/deps/folly.exploded/include/folly/synchronization/SanitizeThread.h:99 (ep.so+0x0000000bb5b6)
     #3 folly::SharedMutexImpl<false, void, std::atomic, false, true>::annotateAcquired(folly::annotate_rwlock_level) .../build/tlm/deps/folly.exploded/include/folly/SharedMutex.h:696 (ep.so+0x0000000bb5b6)
     #4 folly::SharedMutexImpl<false, void, std::atomic, false, true>::lock_shared(folly::SharedMutexToken&) .../build/tlm/deps/folly.exploded/include/folly/SharedMutex.h:376 (ep.so+0x0000000bb5b6)
     #5 folly::SharedMutexImpl<false, void, std::atomic, false, true>::ReadHolder::ReadHolder(...) .../build/tlm/deps/folly.exploded/include/folly/SharedMutex.h:1315 (ep.so+0x0000000bb5b6)
     #6 ActiveStream::setDead(end_stream_status_t) .../kv_engine/engines/ep/src/dcp/active_stream.cc:1181 (ep.so+0x0000000bb5b6)
     #7 operator() .../kv_engine/engines/ep/src/dcp/producer.cc:1491 (ep.so+0x0000001207df)
     #8 for_each<..., DcpProducer::setDisconnect()::<lambda(folly::AtomicHashMap<...>::value_type&)> > /usr/local/include/c++/7.3.0/bits/stl_algo.h:3884 (ep.so+0x0000001207df)
     #9 DcpProducer::setDisconnect() .../kv_engine/engines/ep/src/dcp/producer.cc:1493 (ep.so+0x000000120b08)

   Mutex M201671426334441480 previously acquired by the same thread here:
     #0 pthread_rwlock_rdlock <null> (libtsan.so.0+0x00000002953b)
     #1 cb_rw_reader_enter(pthread_rwlock_t*) .../platform/src/cb_pthreads.cc:195 (libplatform_so.so.0.1.0+0x000000009cfa)
     #2 cb::RWLock::readerLock() .../platform/include/platform/rwlock.h:87 (ep.so+0x0000001205e9)
     #3 cb::RWLock::lock_shared() .../platform/include/platform/rwlock.h:67 (ep.so+0x0000001205e9)
     #4 std::shared_lock<cb::RWLock>::shared_lock(cb::RWLock&) /usr/local/include/c++/7.3.0/shared_mutex:553 (ep.so+0x0000001205e9)
     #5 StreamContainer<std::shared_ptr<Stream> >::ReadLockedHandle::ReadLockedHandle(StreamContainer<std::shared_ptr<Stream> > const&) .../kv_engine/engines/ep/src/dcp/stream_container.h:213 (ep.so+0x0000001205e9)
     #6 StreamContainer<std::shared_ptr<Stream> >::rlock() const .../kv_engine/engines/ep/src/dcp/stream_container.h:273 (ep.so+0x0000001205e9)
     #7 operator() .../kv_engine/engines/ep/src/dcp/producer.cc:1490 (ep.so+0x0000001205e9)
     #8 for_each<..., DcpProducer::setDisconnect()::<lambda(folly::AtomicHashMap<...>::value_type&)> > /usr/local/include/c++/7.3.0/bits/stl_algo.h:3884 (ep.so+0x0000001207df)
     #9 DcpProducer::setDisconnect() .../kv_engine/engines/ep/src/dcp/producer.cc:1493 (ep.so+0x000000120b08)

Change-Id: Ibb2ae11498c7226514bc18788778878bd6c87363
Reviewed-on: http://review.couchbase.org/111905
Reviewed-by: Dave Rigby <[email protected]>
Tested-by: Build Bot <[email protected]>
  • Loading branch information
@jameseh96 @owend74
jameseh96 authored and owend74 committed Jul 15, 2019
1 parent 1c08303 commit 9378b9e
Showing 1 changed file with 8 additions and 1 deletion.
9 changes: 8 additions & 1 deletion engines/ep/src/dcp/producer.cc
View file
Original file line number Diff line number Diff line change
Expand Up @@ -1487,8 +1487,15 @@ void DcpProducer::setDisconnect() {
ConnHandler::setDisconnect();
std::for_each(
streams.begin(), streams.end(), [](StreamsMap::value_type& vt) {
std::vector<std::shared_ptr<Stream>> streamPtrs;
// MB-35049: hold StreamContainer rlock while calling setDead
// leads to lock inversion - so collect sharedptrs in one pass
// then setDead once it is released (itr out of scope).
for (auto itr = vt.second->rlock(); !itr.end(); itr.next()) {
itr.get()->setDead(END_STREAM_DISCONNECTED);
streamPtrs.push_back(itr.get());
}
for (auto stream : streamPtrs) {
stream->setDead(END_STREAM_DISCONNECTED);
}
});
}
Expand Down

0 comments on commit 9378b9e

Please sign in to comment.