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wait_event_lock_irq_cmd(9) [centos man page]

WAIT_EVENT_LOCK_IRQ_(9) 					   Driver Basics					   WAIT_EVENT_LOCK_IRQ_(9)

wait_event_lock_irq_cmd - sleep until a condition gets true. The condition is checked under the lock. This is expected to be called with the lock taken. SYNOPSIS
wait_event_lock_irq_cmd(wq, condition, lock, cmd); ARGUMENTS
wq the waitqueue to wait on condition a C expression for the event to wait for lock a locked spinlock_t, which will be released before cmd and schedule and reacquired afterwards. cmd a command which is invoked outside the critical section before sleep DESCRIPTION
The process is put to sleep (TASK_UNINTERRUPTIBLE) until the condition evaluates to true. The condition is checked each time the waitqueue wq is woken up. wake_up has to be called after changing any variable that could change the result of the wait condition. This is supposed to be called while holding the lock. The lock is dropped before invoking the cmd and going to sleep and is reacquired afterwards. COPYRIGHT
Kernel Hackers Manual 3.10 June 2014 WAIT_EVENT_LOCK_IRQ_(9)

Check Out this Related Man Page

sem_wait(2)							System Calls Manual						       sem_wait(2)

sem_wait, sem_trywait - lock a POSIX semaphore SYNOPSIS
is used to lock a semaphore. The calling thread will not return from its call to until one of the following events occur: it successfully obtains a lock on the semaphore; it is interrupted by a signal or an error condition occurs. is used to lock a semaphore, if it is available. The value of the semaphore sem is checked at some unspecified time during the call. If the semaphore is available at the time its value is checked, the calling thread will atomically, with respect to the checking of the value, lock the semaphore. The thread will now own a lock on the semaphore; the call will return successfully. If the semaphore is unavailable at the time its value is checked, then the call returns -1 with errno set to EAGAIN. If the specified semaphore referred to by sem is a named semaphore, then this semaphore must have been opened by the calling process with The calling process must have both read and write permissions on the semaphore to perform these operations. The semaphore will be locked upon successful return and will stay locked until it is explicitly released by a call to To use this function, link in the realtime library by specifying on the compiler or linker command line. EXAMPLES
The following call to will lock the semaphore sem. The following call to will lock the semaphore sem, if it is available. RETURN VALUE
A successful call to will return 0 and the calling thread will then own a lock on the semaphore. Otherwise, the call to will return -1 with errno set to the appropriate value of the error condition. A successful call to will return 0, if the semaphore was available and the calling thread was able to lock the semaphore. Otherwise, the call to will return -1 with errno set to the appropriate value of the error condition. ERRORS
and fail and do not perform the requested operation if any of the following conditions are encountered: [EPERM] The calling process does not have the privileges necessary to lock the semaphore. [EAGAIN] The semaphore was not available and hence could not be locked by This error condition only occurs in [EINVAL] The argument sem does not refer to a valid semaphore. [EINTR] The function was interrupted by a signal SEE ALSO
sem_post(2), <semaphore.h>. STANDARDS CONFORMANCE

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