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pespin gerrit-no-reply at lists.osmocom.orgpespin has submitted this change. ( https://gerrit.osmocom.org/c/osmo-trx/+/19206 ) Change subject: Transceiver: Fix race condition obtaining Dl burst from Upper layer ...................................................................... Transceiver: Fix race condition obtaining Dl burst from Upper layer The queue was being accessed sequentially obtaining and releasing the mutual exclusion zone twice. First in getStaleBurst() dropping all FN<currTime, then in getCurrentBurst() trying to obtain FN=currTime. However, since in between the mutex is released, it could happen that for instance upper layer would introduce currTime-1 in the queue, which would make then getCurrentBurst() detect that one instead of potential currTime in the queue and return NULL. By holding the mutex during the call to both functions we make sure the state is kept during the whole transaction. Related: OS#4487 (comment #7) Change-Id: If1fd8d7fc5f21ee2894192ef1ac2a3cdda6bbb98 --- M Transceiver52M/Transceiver.cpp M Transceiver52M/radioVector.cpp M Transceiver52M/radioVector.h 3 files changed, 17 insertions(+), 23 deletions(-) Approvals: fixeria: Looks good to me, but someone else must approve laforge: Looks good to me, approved Jenkins Builder: Verified diff --git a/Transceiver52M/Transceiver.cpp b/Transceiver52M/Transceiver.cpp index d45a28b..7aaf1d4 100644 --- a/Transceiver52M/Transceiver.cpp +++ b/Transceiver52M/Transceiver.cpp @@ -433,9 +433,15 @@ std::vector<bool> filler(mChans, true); bool stale_bursts_changed; + TN = nowTime.TN(); + for (size_t i = 0; i < mChans; i ++) { state = &mStates[i]; stale_bursts_changed = false; + zeros[i] = state->chanType[TN] == NONE; + + Mutex *mtx = mTxPriorityQueues[i].getMutex(); + mtx->lock(); while ((burst = mTxPriorityQueues[i].getStaleBurst(nowTime))) { LOGCHAN(i, DTRXDDL, NOTICE) << "dumping STALE burst in TRX->SDR interface (" @@ -447,15 +453,6 @@ delete burst; } - if (stale_bursts_changed) - dispatch_trx_rate_ctr_change(state, i); - - TN = nowTime.TN(); - modFN = nowTime.FN() % state->fillerModulus[TN]; - - bursts[i] = state->fillerTable[modFN][TN]; - zeros[i] = state->chanType[TN] == NONE; - if ((burst = mTxPriorityQueues[i].getCurrentBurst(nowTime))) { bursts[i] = burst->getVector(); @@ -467,7 +464,15 @@ } delete burst; + } else { + modFN = nowTime.FN() % state->fillerModulus[TN]; + bursts[i] = state->fillerTable[modFN][TN]; } + + mtx->unlock(); + + if (stale_bursts_changed) + dispatch_trx_rate_ctr_change(state, i); } mRadioInterface->driveTransmitRadio(bursts, zeros); diff --git a/Transceiver52M/radioVector.cpp b/Transceiver52M/radioVector.cpp index ad40a11..68e42c5 100644 --- a/Transceiver52M/radioVector.cpp +++ b/Transceiver52M/radioVector.cpp @@ -120,38 +120,26 @@ radioVector* VectorQueue::getStaleBurst(const GSM::Time& targTime) { - mLock.lock(); - if ((mQ.size()==0)) { - mLock.unlock(); + if ((mQ.size()==0)) return NULL; - } if (mQ.top()->getTime() < targTime) { radioVector* retVal = mQ.top(); mQ.pop(); - mLock.unlock(); return retVal; } - mLock.unlock(); - return NULL; } radioVector* VectorQueue::getCurrentBurst(const GSM::Time& targTime) { - mLock.lock(); - if ((mQ.size()==0)) { - mLock.unlock(); + if ((mQ.size()==0)) return NULL; - } if (mQ.top()->getTime() == targTime) { radioVector* retVal = mQ.top(); mQ.pop(); - mLock.unlock(); return retVal; } - mLock.unlock(); - return NULL; } diff --git a/Transceiver52M/radioVector.h b/Transceiver52M/radioVector.h index 0a14a4d..84e3987 100644 --- a/Transceiver52M/radioVector.h +++ b/Transceiver52M/radioVector.h @@ -65,6 +65,7 @@ GSM::Time nextTime() const; radioVector* getStaleBurst(const GSM::Time& targTime); radioVector* getCurrentBurst(const GSM::Time& targTime); + Mutex *getMutex() const { return &mLock; }; }; #endif /* RADIOVECTOR_H */ -- To view, visit https://gerrit.osmocom.org/c/osmo-trx/+/19206 To unsubscribe, or for help writing mail filters, visit https://gerrit.osmocom.org/settings Gerrit-Project: osmo-trx Gerrit-Branch: master Gerrit-Change-Id: If1fd8d7fc5f21ee2894192ef1ac2a3cdda6bbb98 Gerrit-Change-Number: 19206 Gerrit-PatchSet: 3 Gerrit-Owner: pespin <pespin at sysmocom.de> Gerrit-Reviewer: Jenkins Builder Gerrit-Reviewer: fixeria <vyanitskiy at sysmocom.de> Gerrit-Reviewer: laforge <laforge at osmocom.org> Gerrit-Reviewer: pespin <pespin at sysmocom.de> Gerrit-MessageType: merged -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://lists.osmocom.org/pipermail/gerrit-log/attachments/20200714/14cb8414/attachment.htm>