Linux Device Drivers Development

Spinlock versus mutexes

Used for concurrency in the kernel, spinlocks and mutexes both have their own objectives:

• Mutexes protect the process's critical resources, whereas spinlocks protect the IRQ handler's critical sections
• Mutexes put contenders to sleep until the lock is acquired, whereas spinlocks infinitely spin in a loop (consuming CPU) until the lock is acquired
• Because of the previous point, you can't hold spinlocks for a long time, since waiters will waste CPU time waiting for the lock, whereas a mutex can be held as long as the resource needs to be protected, since contenders are put to sleep in a wait queue

When dealing with spinlocks, please keep in mind that preemption is disabled only for threads holding spinlocks, not for ...