326 lines
11 KiB
C
326 lines
11 KiB
C
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/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_WAIT_BIT_H
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#define _LINUX_WAIT_BIT_H
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/*
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* Linux wait-bit related types and methods:
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*/
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#include <linux/wait.h>
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struct wait_bit_key {
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void *flags;
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int bit_nr;
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unsigned long timeout;
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};
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struct wait_bit_queue_entry {
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struct wait_bit_key key;
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struct wait_queue_entry wq_entry;
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};
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#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
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{ .flags = word, .bit_nr = bit, }
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typedef int wait_bit_action_f(struct wait_bit_key *key, int mode);
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void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit);
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int __wait_on_bit(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
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int __wait_on_bit_lock(struct wait_queue_head *wq_head, struct wait_bit_queue_entry *wbq_entry, wait_bit_action_f *action, unsigned int mode);
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void wake_up_bit(void *word, int bit);
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int out_of_line_wait_on_bit(void *word, int, wait_bit_action_f *action, unsigned int mode);
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int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
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int out_of_line_wait_on_bit_lock(void *word, int, wait_bit_action_f *action, unsigned int mode);
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struct wait_queue_head *bit_waitqueue(void *word, int bit);
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extern void __init wait_bit_init(void);
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int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
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#define DEFINE_WAIT_BIT(name, word, bit) \
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struct wait_bit_queue_entry name = { \
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.key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \
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.wq_entry = { \
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.private = current, \
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.func = wake_bit_function, \
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.entry = \
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LIST_HEAD_INIT((name).wq_entry.entry), \
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}, \
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}
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extern int bit_wait(struct wait_bit_key *key, int mode);
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extern int bit_wait_io(struct wait_bit_key *key, int mode);
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extern int bit_wait_timeout(struct wait_bit_key *key, int mode);
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extern int bit_wait_io_timeout(struct wait_bit_key *key, int mode);
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/**
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* wait_on_bit - wait for a bit to be cleared
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @mode: the task state to sleep in
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*
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* There is a standard hashed waitqueue table for generic use. This
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* is the part of the hashtable's accessor API that waits on a bit.
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* For instance, if one were to have waiters on a bitflag, one would
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* call wait_on_bit() in threads waiting for the bit to clear.
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* One uses wait_on_bit() where one is waiting for the bit to clear,
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* but has no intention of setting it.
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* Returned value will be zero if the bit was cleared, or non-zero
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* if the process received a signal and the mode permitted wakeup
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* on that signal.
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*/
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static inline int
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wait_on_bit(unsigned long *word, int bit, unsigned mode)
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{
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might_sleep();
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if (!test_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit(word, bit,
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bit_wait,
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mode);
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}
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/**
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* wait_on_bit_io - wait for a bit to be cleared
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @mode: the task state to sleep in
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*
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* Use the standard hashed waitqueue table to wait for a bit
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* to be cleared. This is similar to wait_on_bit(), but calls
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* io_schedule() instead of schedule() for the actual waiting.
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*
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* Returned value will be zero if the bit was cleared, or non-zero
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* if the process received a signal and the mode permitted wakeup
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* on that signal.
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*/
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static inline int
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wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
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{
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might_sleep();
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if (!test_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit(word, bit,
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bit_wait_io,
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mode);
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}
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/**
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* wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @mode: the task state to sleep in
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* @timeout: timeout, in jiffies
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*
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* Use the standard hashed waitqueue table to wait for a bit
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* to be cleared. This is similar to wait_on_bit(), except also takes a
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* timeout parameter.
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*
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* Returned value will be zero if the bit was cleared before the
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* @timeout elapsed, or non-zero if the @timeout elapsed or process
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* received a signal and the mode permitted wakeup on that signal.
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*/
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static inline int
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wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
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unsigned long timeout)
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{
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might_sleep();
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if (!test_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit_timeout(word, bit,
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bit_wait_timeout,
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mode, timeout);
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}
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/**
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* wait_on_bit_action - wait for a bit to be cleared
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @action: the function used to sleep, which may take special actions
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* @mode: the task state to sleep in
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*
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* Use the standard hashed waitqueue table to wait for a bit
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* to be cleared, and allow the waiting action to be specified.
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* This is like wait_on_bit() but allows fine control of how the waiting
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* is done.
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*
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* Returned value will be zero if the bit was cleared, or non-zero
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* if the process received a signal and the mode permitted wakeup
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* on that signal.
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*/
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static inline int
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wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
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unsigned mode)
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{
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might_sleep();
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if (!test_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit(word, bit, action, mode);
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}
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/**
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* wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @mode: the task state to sleep in
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*
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* There is a standard hashed waitqueue table for generic use. This
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* is the part of the hashtable's accessor API that waits on a bit
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* when one intends to set it, for instance, trying to lock bitflags.
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* For instance, if one were to have waiters trying to set bitflag
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* and waiting for it to clear before setting it, one would call
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* wait_on_bit() in threads waiting to be able to set the bit.
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* One uses wait_on_bit_lock() where one is waiting for the bit to
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* clear with the intention of setting it, and when done, clearing it.
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*
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* Returns zero if the bit was (eventually) found to be clear and was
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* set. Returns non-zero if a signal was delivered to the process and
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* the @mode allows that signal to wake the process.
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*/
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static inline int
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wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
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{
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might_sleep();
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if (!test_and_set_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
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}
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/**
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* wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @mode: the task state to sleep in
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*
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* Use the standard hashed waitqueue table to wait for a bit
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* to be cleared and then to atomically set it. This is similar
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* to wait_on_bit(), but calls io_schedule() instead of schedule()
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* for the actual waiting.
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*
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* Returns zero if the bit was (eventually) found to be clear and was
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* set. Returns non-zero if a signal was delivered to the process and
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* the @mode allows that signal to wake the process.
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*/
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static inline int
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wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
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{
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might_sleep();
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if (!test_and_set_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
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}
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/**
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* wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
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* @word: the word being waited on, a kernel virtual address
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* @bit: the bit of the word being waited on
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* @action: the function used to sleep, which may take special actions
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* @mode: the task state to sleep in
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*
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* Use the standard hashed waitqueue table to wait for a bit
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* to be cleared and then to set it, and allow the waiting action
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* to be specified.
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* This is like wait_on_bit() but allows fine control of how the waiting
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* is done.
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*
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* Returns zero if the bit was (eventually) found to be clear and was
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* set. Returns non-zero if a signal was delivered to the process and
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* the @mode allows that signal to wake the process.
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*/
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static inline int
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wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
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unsigned mode)
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{
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might_sleep();
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if (!test_and_set_bit(bit, word))
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return 0;
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return out_of_line_wait_on_bit_lock(word, bit, action, mode);
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}
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extern void init_wait_var_entry(struct wait_bit_queue_entry *wbq_entry, void *var, int flags);
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extern void wake_up_var(void *var);
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extern wait_queue_head_t *__var_waitqueue(void *p);
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#define ___wait_var_event(var, condition, state, exclusive, ret, cmd) \
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({ \
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__label__ __out; \
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struct wait_queue_head *__wq_head = __var_waitqueue(var); \
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struct wait_bit_queue_entry __wbq_entry; \
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long __ret = ret; /* explicit shadow */ \
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\
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init_wait_var_entry(&__wbq_entry, var, \
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exclusive ? WQ_FLAG_EXCLUSIVE : 0); \
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for (;;) { \
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long __int = prepare_to_wait_event(__wq_head, \
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&__wbq_entry.wq_entry, \
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state); \
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if (condition) \
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break; \
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\
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if (___wait_is_interruptible(state) && __int) { \
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__ret = __int; \
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goto __out; \
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} \
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\
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cmd; \
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} \
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finish_wait(__wq_head, &__wbq_entry.wq_entry); \
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__out: __ret; \
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})
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#define __wait_var_event(var, condition) \
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___wait_var_event(var, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
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schedule())
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#define wait_var_event(var, condition) \
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do { \
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might_sleep(); \
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if (condition) \
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break; \
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__wait_var_event(var, condition); \
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} while (0)
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#define __wait_var_event_killable(var, condition) \
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___wait_var_event(var, condition, TASK_KILLABLE, 0, 0, \
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schedule())
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#define wait_var_event_killable(var, condition) \
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({ \
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int __ret = 0; \
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might_sleep(); \
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if (!(condition)) \
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__ret = __wait_var_event_killable(var, condition); \
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__ret; \
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})
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#define __wait_var_event_timeout(var, condition, timeout) \
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___wait_var_event(var, ___wait_cond_timeout(condition), \
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TASK_UNINTERRUPTIBLE, 0, timeout, \
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__ret = schedule_timeout(__ret))
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#define wait_var_event_timeout(var, condition, timeout) \
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({ \
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long __ret = timeout; \
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might_sleep(); \
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if (!___wait_cond_timeout(condition)) \
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__ret = __wait_var_event_timeout(var, condition, timeout); \
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__ret; \
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})
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/**
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* clear_and_wake_up_bit - clear a bit and wake up anyone waiting on that bit
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*
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* @bit: the bit of the word being waited on
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* @word: the word being waited on, a kernel virtual address
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*
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* You can use this helper if bitflags are manipulated atomically rather than
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* non-atomically under a lock.
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*/
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static inline void clear_and_wake_up_bit(int bit, void *word)
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{
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clear_bit_unlock(bit, word);
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/* See wake_up_bit() for which memory barrier you need to use. */
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smp_mb__after_atomic();
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wake_up_bit(word, bit);
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}
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#endif /* _LINUX_WAIT_BIT_H */
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