spdk_spinlock Struct Reference

A spinlock augmented with safety checks for use with SPDK. More...

#include <thread.h>

Data Fields
pthread_spinlock_t	spinlock
struct spdk_thread *	thread
struct spdk_spinlock_internal *	internal
bool	initialized
bool	destroyed

Detailed Description

A spinlock augmented with safety checks for use with SPDK.

SPDK code that uses spdk_spinlock runs from an SPDK thread, which itself is associated with a pthread. There are typically many SPDK threads associated with each pthread. The SPDK application may migrate SPDK threads between pthreads from time to time to balance the load on those threads. Migration of SPDK threads only happens when the thread is off CPU, and as such it is only safe to hold a lock so long as an SPDK thread stays on CPU.

It is not safe to lock a spinlock, return from the event or poller, then unlock it at some later time because:

• Even though the SPDK thread may be the same, the SPDK thread may be running on different pthreads during lock and unlock. A pthread spinlock may consider this to be an unlock by a non-owner, which results in undefined behavior.
• A lock that is acquired by a poller or event may be needed by another poller or event that runs on the same pthread. This can lead to deadlock or detection of deadlock.
• A lock that is acquired by a poller or event that is needed by another poller or event that runs on a second pthread will block the second pthread from doing any useful work until the lock is released. Because the lock holder and the lock acquirer are on the same pthread, this would lead to deadlock.

If an SPDK spinlock is used erroneously, the program will abort.

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The documentation for this struct was generated from the following file:

• thread.h