spinlock & mutex

spinlock ensures only one thread can enter critical section

spinlock example:

#include

spinlock_t mylock = SPIN_LOCK_UNLOCKED; /* Initialize */

/* Acquire the spinlock. This is inexpensive if there

 * is no one inside the critical section. In the face of

 * contention, spinlock() has to busy-wait.

 */

spin_lock(&mylock);

/* ... Critical Section code ... */

spin_unlock(&mylock); /* Release the lock */

spinlock will busy-wait,  mutex will sleep

mutex example:

#include

/* Statically declare a mutex. To dynamically

   create a mutex, use mutex_init() */

static DEFINE_MUTEX(mymutex);

/* Acquire the mutex. This is inexpensive if there

 * is no one inside the critical section. In the face of

 * contention, mutex_lock() puts the calling thread to sleep.

 */

mutex_lock(&mymutex);

/* ... Critical Section code ... */

mutex_unlock(&mymutex);      /* Release the mutex */