12/14/2023 0 Comments Lock queue lock 52A spin lock must always be acquired or released either as a queued spin lock, or as an ordinary spin lock. For a description of when to use spin locks, see KeAcquireSpinLock.ĭrivers must not combine calls to KeAcquireSpinLock and KeAcquireInStackQueuedSpinLock on the same spin lock. If both unit locks as well as queue locks are created within an application LUW, then the queue locks are always set first and then the unit locks are assigned to the appropriate queues. All queue locks become active at the next COMMIT WORK. An empty unit is created to map the lock. Like ordinary spin locks, queued spin locks must only be used in very special circumstances. This makes it possible to lock a queue preemptively. For a driver that is running at IRQL = DISPATCH_LEVEL, this routine improves performance by acquiring the lock without first setting the IRQL to DISPATCH_LEVEL, which, in this case, would be a redundant operation. Otherwise, use the KeAcquireInStackQueuedSpinLock routine to acquire the spin lock.įor a driver that is running at IRQL > DISPATCH_LEVEL, this routine acquires the lock without modifying the current IRQL. To release the spin lock, call the KeReleaseInStackQueuedSpinLockFromDpcLevel routine.ĭrivers that are already running at an IRQL >= DISPATCH_LEVEL can call this routine to acquire the queued spin lock more quickly. For more information, see Queued Spin Locks. Return valueįor a driver running at IRQL >= DISPATCH_LEVEL, KeAcquireInStackQueuedSpinLockAtDpcLevel acquires a spin lock as a queued spin lock. To release the lock, the caller passes this value to the KeReleaseInStackQueuedSpinLockFromDpcLevel routine. Pointer to a caller-supplied KLOCK_QUEUE_HANDLE structure that the routine can use to return the spin lock queue handle. This parameter must have been initialized by a call to the KeInitializeSpinLock routine. Syntax void KeAcquireInStackQueuedSpinLockAtDpcLevel( Interval-Based Memory Reclamation, Haosen Wen et al., Proceedings of the 23rd ACM SIGPLAN Symposium on Principles and Practice of Parallel Programming (PPoPP), 2018.The KeAcquireInStackQueuedSpinLockAtDpcLevel routine acquires a queued spin lock when the caller is already running at IRQL >= DISPATCH_LEVEL. McKenney et al., Ottawa Linux Symposium, 2002. Hart et al., Journal of Parallel and Distributed Computing, 2007. Performance of Memory Reclamation for Lockless Synchronization, Thomas E. Michael, IEEE Transactions on Parallel and Distributed Systems, 2004. Hazard Pointers: Safe Memory Reclamation for Lock-Free Objects, Maged M. This is a general problem in non-blocking data structures and we generally don't consider it as the bug of the data structure itself-after all it only occurs in languages using manual memory management like C/C++ but not in those like Java (BTW, Michael & Scott Queue has been adopted in Java Concurrency for years). The paper of Interval-Based Memory Reclamation has much background discussed. You can take a look at these papers referred below for more details. As far as I know, epoch-based reclamations are widely adopted to handle this problem. They avoid use-after-free by reserving epochs and are faster than Hazard Pointers. There're also many epoch-based reclamation variants such as RCU, and most recently, interval-based reclamation (IBR). However, this mechanism incurs nontrivial performance overhead. Hazard Pointers allow the thread to reserve blocks so that other threads won't really reclaim them before it finishes. This is actually the non-blocking memory reclamation problem that’s being explored years since Maged Michael, one of the authors of MS queue, introduced Hazard Pointers. Thread 1 continues and advanced to D4, trying to read head.ptr->next, but as head.ptr is already freed by Thread 1, crash happens.Īnd my C++ code really always crashes at D4 for Thread 1.Ĭan anyone please point out my mistake and give some explanation ?.
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