futex_requeue (9)

int futex_requeue(u32 __user * uaddr1, unsigned int flags, u32 __user * uaddr2, int nr_wake, int nr_requeue, u32 * cmpval, int requeue_pi);

uaddr1

source futex user address

flags

futex flags (FLAGS_SHARED, etc.)

uaddr2

target futex user address

nr_wake

number of waiters to wake (must be 1 for requeue_pi)

nr_requeue

number of waiters to requeue (0-INT_MAX)

cmpval

uaddr1 expected value (or NULL)

requeue_pi

if we are attempting to requeue from a non-pi futex to a pi futex (pi to pi requeue is not supported)

Requeue waiters on uaddr1 to uaddr2. In the requeue_pi case, try to acquire uaddr2 atomically on behalf of the top waiter.

>=0 - on success, the number of tasks requeued or woken; <0 - on error

Rusty Russell <[email protected]>

Author.