WAKE_UP_BIT(9) Driver Basics WAKE_UP_BIT(9)NAMEwake_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_clear_bit, 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.
COPYRIGHTKernel Hackers Manual 3.11 November 2013 WAKE_UP_BIT(9)
