v4.19.13 snapshot.
diff --git a/include/linux/wait_bit.h b/include/linux/wait_bit.h
new file mode 100644
index 0000000..2b0072f
--- /dev/null
+++ b/include/linux/wait_bit.h
@@ -0,0 +1,325 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _LINUX_WAIT_BIT_H
+#define _LINUX_WAIT_BIT_H
+
+/*
+ * Linux wait-bit related types and methods:
+ */
+#include <linux/wait.h>
+
+struct wait_bit_key {
+ void *flags;
+ int bit_nr;
+ unsigned long timeout;
+};
+
+struct wait_bit_queue_entry {
+ struct wait_bit_key key;
+ struct wait_queue_entry wq_entry;
+};
+
+#define __WAIT_BIT_KEY_INITIALIZER(word, bit) \
+ { .flags = word, .bit_nr = bit, }
+
+typedef int wait_bit_action_f(struct wait_bit_key *key, int mode);
+
+void __wake_up_bit(struct wait_queue_head *wq_head, void *word, int bit);
+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);
+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);
+void wake_up_bit(void *word, int bit);
+int out_of_line_wait_on_bit(void *word, int, wait_bit_action_f *action, unsigned int mode);
+int out_of_line_wait_on_bit_timeout(void *word, int, wait_bit_action_f *action, unsigned int mode, unsigned long timeout);
+int out_of_line_wait_on_bit_lock(void *word, int, wait_bit_action_f *action, unsigned int mode);
+struct wait_queue_head *bit_waitqueue(void *word, int bit);
+extern void __init wait_bit_init(void);
+
+int wake_bit_function(struct wait_queue_entry *wq_entry, unsigned mode, int sync, void *key);
+
+#define DEFINE_WAIT_BIT(name, word, bit) \
+ struct wait_bit_queue_entry name = { \
+ .key = __WAIT_BIT_KEY_INITIALIZER(word, bit), \
+ .wq_entry = { \
+ .private = current, \
+ .func = wake_bit_function, \
+ .entry = \
+ LIST_HEAD_INIT((name).wq_entry.entry), \
+ }, \
+ }
+
+extern int bit_wait(struct wait_bit_key *key, int mode);
+extern int bit_wait_io(struct wait_bit_key *key, int mode);
+extern int bit_wait_timeout(struct wait_bit_key *key, int mode);
+extern int bit_wait_io_timeout(struct wait_bit_key *key, int mode);
+
+/**
+ * wait_on_bit - wait for a bit to be cleared
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @mode: the task state to sleep in
+ *
+ * There is a standard hashed waitqueue table for generic use. This
+ * is the part of the hashtable's accessor API that waits on a bit.
+ * For instance, if one were to have waiters on a bitflag, one would
+ * call wait_on_bit() in threads waiting for the bit to clear.
+ * One uses wait_on_bit() where one is waiting for the bit to clear,
+ * but has no intention of setting it.
+ * Returned value will be zero if the bit was cleared, or non-zero
+ * if the process received a signal and the mode permitted wakeup
+ * on that signal.
+ */
+static inline int
+wait_on_bit(unsigned long *word, int bit, unsigned mode)
+{
+ might_sleep();
+ if (!test_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit(word, bit,
+ bit_wait,
+ mode);
+}
+
+/**
+ * wait_on_bit_io - wait for a bit to be cleared
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @mode: the task state to sleep in
+ *
+ * Use the standard hashed waitqueue table to wait for a bit
+ * to be cleared. This is similar to wait_on_bit(), but calls
+ * io_schedule() instead of schedule() for the actual waiting.
+ *
+ * Returned value will be zero if the bit was cleared, or non-zero
+ * if the process received a signal and the mode permitted wakeup
+ * on that signal.
+ */
+static inline int
+wait_on_bit_io(unsigned long *word, int bit, unsigned mode)
+{
+ might_sleep();
+ if (!test_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit(word, bit,
+ bit_wait_io,
+ mode);
+}
+
+/**
+ * wait_on_bit_timeout - wait for a bit to be cleared or a timeout elapses
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @mode: the task state to sleep in
+ * @timeout: timeout, in jiffies
+ *
+ * Use the standard hashed waitqueue table to wait for a bit
+ * to be cleared. This is similar to wait_on_bit(), except also takes a
+ * timeout parameter.
+ *
+ * Returned value will be zero if the bit was cleared before the
+ * @timeout elapsed, or non-zero if the @timeout elapsed or process
+ * received a signal and the mode permitted wakeup on that signal.
+ */
+static inline int
+wait_on_bit_timeout(unsigned long *word, int bit, unsigned mode,
+ unsigned long timeout)
+{
+ might_sleep();
+ if (!test_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit_timeout(word, bit,
+ bit_wait_timeout,
+ mode, timeout);
+}
+
+/**
+ * wait_on_bit_action - wait for a bit to be cleared
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @action: the function used to sleep, which may take special actions
+ * @mode: the task state to sleep in
+ *
+ * Use the standard hashed waitqueue table to wait for a bit
+ * to be cleared, and allow the waiting action to be specified.
+ * This is like wait_on_bit() but allows fine control of how the waiting
+ * is done.
+ *
+ * Returned value will be zero if the bit was cleared, or non-zero
+ * if the process received a signal and the mode permitted wakeup
+ * on that signal.
+ */
+static inline int
+wait_on_bit_action(unsigned long *word, int bit, wait_bit_action_f *action,
+ unsigned mode)
+{
+ might_sleep();
+ if (!test_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit(word, bit, action, mode);
+}
+
+/**
+ * wait_on_bit_lock - wait for a bit to be cleared, when wanting to set it
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @mode: the task state to sleep in
+ *
+ * There is a standard hashed waitqueue table for generic use. This
+ * is the part of the hashtable's accessor API that waits on a bit
+ * when one intends to set it, for instance, trying to lock bitflags.
+ * For instance, if one were to have waiters trying to set bitflag
+ * and waiting for it to clear before setting it, one would call
+ * wait_on_bit() in threads waiting to be able to set the bit.
+ * One uses wait_on_bit_lock() where one is waiting for the bit to
+ * clear with the intention of setting it, and when done, clearing it.
+ *
+ * Returns zero if the bit was (eventually) found to be clear and was
+ * set. Returns non-zero if a signal was delivered to the process and
+ * the @mode allows that signal to wake the process.
+ */
+static inline int
+wait_on_bit_lock(unsigned long *word, int bit, unsigned mode)
+{
+ might_sleep();
+ if (!test_and_set_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit_lock(word, bit, bit_wait, mode);
+}
+
+/**
+ * wait_on_bit_lock_io - wait for a bit to be cleared, when wanting to set it
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @mode: the task state to sleep in
+ *
+ * Use the standard hashed waitqueue table to wait for a bit
+ * to be cleared and then to atomically set it. This is similar
+ * to wait_on_bit(), but calls io_schedule() instead of schedule()
+ * for the actual waiting.
+ *
+ * Returns zero if the bit was (eventually) found to be clear and was
+ * set. Returns non-zero if a signal was delivered to the process and
+ * the @mode allows that signal to wake the process.
+ */
+static inline int
+wait_on_bit_lock_io(unsigned long *word, int bit, unsigned mode)
+{
+ might_sleep();
+ if (!test_and_set_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit_lock(word, bit, bit_wait_io, mode);
+}
+
+/**
+ * wait_on_bit_lock_action - wait for a bit to be cleared, when wanting to set it
+ * @word: the word being waited on, a kernel virtual address
+ * @bit: the bit of the word being waited on
+ * @action: the function used to sleep, which may take special actions
+ * @mode: the task state to sleep in
+ *
+ * Use the standard hashed waitqueue table to wait for a bit
+ * to be cleared and then to set it, and allow the waiting action
+ * to be specified.
+ * This is like wait_on_bit() but allows fine control of how the waiting
+ * is done.
+ *
+ * Returns zero if the bit was (eventually) found to be clear and was
+ * set. Returns non-zero if a signal was delivered to the process and
+ * the @mode allows that signal to wake the process.
+ */
+static inline int
+wait_on_bit_lock_action(unsigned long *word, int bit, wait_bit_action_f *action,
+ unsigned mode)
+{
+ might_sleep();
+ if (!test_and_set_bit(bit, word))
+ return 0;
+ return out_of_line_wait_on_bit_lock(word, bit, action, mode);
+}
+
+extern void init_wait_var_entry(struct wait_bit_queue_entry *wbq_entry, void *var, int flags);
+extern void wake_up_var(void *var);
+extern wait_queue_head_t *__var_waitqueue(void *p);
+
+#define ___wait_var_event(var, condition, state, exclusive, ret, cmd) \
+({ \
+ __label__ __out; \
+ struct wait_queue_head *__wq_head = __var_waitqueue(var); \
+ struct wait_bit_queue_entry __wbq_entry; \
+ long __ret = ret; /* explicit shadow */ \
+ \
+ init_wait_var_entry(&__wbq_entry, var, \
+ exclusive ? WQ_FLAG_EXCLUSIVE : 0); \
+ for (;;) { \
+ long __int = prepare_to_wait_event(__wq_head, \
+ &__wbq_entry.wq_entry, \
+ state); \
+ if (condition) \
+ break; \
+ \
+ if (___wait_is_interruptible(state) && __int) { \
+ __ret = __int; \
+ goto __out; \
+ } \
+ \
+ cmd; \
+ } \
+ finish_wait(__wq_head, &__wbq_entry.wq_entry); \
+__out: __ret; \
+})
+
+#define __wait_var_event(var, condition) \
+ ___wait_var_event(var, condition, TASK_UNINTERRUPTIBLE, 0, 0, \
+ schedule())
+
+#define wait_var_event(var, condition) \
+do { \
+ might_sleep(); \
+ if (condition) \
+ break; \
+ __wait_var_event(var, condition); \
+} while (0)
+
+#define __wait_var_event_killable(var, condition) \
+ ___wait_var_event(var, condition, TASK_KILLABLE, 0, 0, \
+ schedule())
+
+#define wait_var_event_killable(var, condition) \
+({ \
+ int __ret = 0; \
+ might_sleep(); \
+ if (!(condition)) \
+ __ret = __wait_var_event_killable(var, condition); \
+ __ret; \
+})
+
+#define __wait_var_event_timeout(var, condition, timeout) \
+ ___wait_var_event(var, ___wait_cond_timeout(condition), \
+ TASK_UNINTERRUPTIBLE, 0, timeout, \
+ __ret = schedule_timeout(__ret))
+
+#define wait_var_event_timeout(var, condition, timeout) \
+({ \
+ long __ret = timeout; \
+ might_sleep(); \
+ if (!___wait_cond_timeout(condition)) \
+ __ret = __wait_var_event_timeout(var, condition, timeout); \
+ __ret; \
+})
+
+/**
+ * clear_and_wake_up_bit - clear a bit and wake up anyone waiting on that bit
+ *
+ * @bit: the bit of the word being waited on
+ * @word: the word being waited on, a kernel virtual address
+ *
+ * You can use this helper if bitflags are manipulated atomically rather than
+ * non-atomically under a lock.
+ */
+static inline void clear_and_wake_up_bit(int bit, void *word)
+{
+ clear_bit_unlock(bit, word);
+ /* See wake_up_bit() for which memory barrier you need to use. */
+ smp_mb__after_atomic();
+ wake_up_bit(word, bit);
+}
+
+#endif /* _LINUX_WAIT_BIT_H */