SVR5

SLEEP_LOCK_SIG(D3)

SLEEP_LOCK_SIG -- acquire a sleep lock

Synopsis

   #include <sys/types.h>
   #include <sys/ksynch.h>
   #include <sys/ddi.h>
   
   bool_t SLEEP_LOCK_SIG(sleep_t *lockp, int priority);

Description

SLEEP_LOCK_SIG acquires the sleep lock specified by lockp. If the lock is not immediately available, the caller is put to sleep (the caller's execution is suspended and other processes may be scheduled) until the lock becomes available to the caller, at which point the caller wakes up and returns with the lock held.

SLEEP_LOCK_SIG may be interrupted by a signal, in which case it may return early without acquiring the lock.

If the function is interrupted by a job control stop signal (e.g. SIGSTOP, SIGTSTP, SIGTTIN, SIGTTOU) which results in the caller entering a stopped state, the SLEEP_LOCK_SIG function will transparently retry the lock operation upon continuing (the call will not return without the lock).

If the function is interrupted by a signal other than a job control stop signal, or by a job control stop signal that does not result in the caller stopping (because the signal has a non-default disposition), the SLEEP_LOCK_SIG call will return early without acquiring the lock.

Arguments

lockp: Pointer to the sleep lock to be acquired.
priority: A hint to the scheduling policy as to the relative priority the caller wishes to be assigned while running in the kernel after waking up.

Return values

SLEEP_LOCK_SIG returns TRUE (a non-zero value) if the lock is successfully acquired or FALSE (zero) if the function returned early because of a signal.

Usage

priority argument

Valid values for priority are:

pridisk: Priority appropriate for disk driver.
prinet: Priority appropriate for network driver.
pritty: Priority appropriate for terminal driver.
pritape: Priority appropriate for tape driver.
prihi: High priority.
primed: Medium priority.
prilo: Low priority.

Drivers may use these values to request a priority appropriate to a given type of device or to request a priority that is high, medium or low relative to other activities within the kernel.

It is also permissible to specify positive or negative offsets from the values defined above. Positive offsets result in more favorable priority. The maximum allowable offset in all cases is 3 (that is, pridisk+3 and pridisk-3 are valid values but pridisk+4 and pridisk-4 are not valid). Offsets can be useful in defining the relative importance of different locks or resources that may be held by a given driver. In general, a higher relative priority should be used when the caller is attempting to acquire a highly contended lock or resource, or when the caller is already holding one or more locks or kernel resources upon entry to SLEEP_LOCK_SIG.

The exact semantic of the priority argument is specific to the scheduling class of the caller, and some scheduling classes may choose to ignore the argument for the purposes of assigning a scheduling priority.

Context and synchronization

User or blockable context.

Warnings

Sleep locks are not recursive. A call to SLEEP_LOCK_SIG attempting to acquire a lock that is currently held by the calling context will result in deadlock.

Hardware applicability

All

Version applicability

ddi: 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp, 8, 8mp

References

SLEEP_ALLOC(D3), SLEEP_DEALLOC(D3), SLEEP_LOCK(D3), SLEEP_LOCKAVAIL(D3), SLEEP_LOCKOWNED(D3), SLEEP_TRYLOCK(D3), SLEEP_UNLOCK(D3), signals(D5)

``Sleep locks'' in HDK Technical Reference