WAKE_UP_BIT(9)                            Driver Basics                            WAKE_UP_BIT(9)



NAME
       wake_up_bit - wake up a waiter on a bit

SYNOPSIS
       void wake_up_bit(void * word, int bit);

ARGUMENTS
       word
           the word being waited on, a kernel virtual address

       bit
           the bit of the word being waited on

DESCRIPTION
       There is a standard hashed waitqueue table for generic use. This is the part of the
       hashtable's accessor API that wakes up waiters on a bit. For instance, if one were to have
       waiters on a bitflag, one would call wake_up_bit after clearing the bit.

       In order for this to function properly, as it uses waitqueue_active internally, some kind
       of memory barrier must be done prior to calling this. Typically, this will be
       smp_mb__after_atomic, but in some cases where bitflags are manipulated non-atomically
       under a lock, one may need to use a less regular barrier, such fs/inode.c's smp_mb,
       because spin_unlock does not guarantee a memory barrier.

COPYRIGHT
Kernel Hackers Manual 4.8.                 January 2017                            WAKE_UP_BIT(9)