On Fri, Feb 11, 2005 at 01:07:08AM -0600, Al Borchers wrote:
>
>
> On Thursday 10 February 2005 9:39 am, Nishanth Aravamudan wrote:
> >> It came up on IRC that the wait_cond*() functions from
> >> usb/serial/gadget.c could be useful in other parts of the kernel. Does
> >> the following patch make sense towards this?
>
> Sure, if people want to use these.
>
> I did not push them because they seemed a bit "heavy weight",
> but the construct is useful and general.
>
> The docs should explain that the purpose is to wait atomically on
> a complex condition, and that the usage pattern is to hold the
> lock when using the wait_event_* functions or when changing any
> variable that might affect the condition and waking up the waiting
> processes.
How does this patch look? I wasn't sure if macros and DocBook-style
comments played well together, and the names of the macros pretty much
explain what they do :)
Description: The following patch attempts to make the wait_cond*()
functions from usb/serial/gadget.c, which are basically the same
as wait_event*() but with locks, globally available via wait.h. Adds a
comment to explain the usage pattern for all of the wait_event*()
macros.
Signed-off-by: Nishanth Aravamudan <[EMAIL PROTECTED]>
--- 2.6.11-rc3-v/include/linux/wait.h 2004-12-24 13:34:57.000000000 -0800
+++ 2.6.11-rc3/include/linux/wait.h 2005-02-11 11:55:07.000000000 -0800
@@ -156,6 +156,32 @@ wait_queue_head_t *FASTCALL(bit_waitqueu
#define wake_up_locked(x) __wake_up_locked((x),
TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE)
#define wake_up_interruptible_sync(x) __wake_up_sync((x),TASK_INTERRUPTIBLE,
1)
+/*
+ * The wait_event*() macros wait atomically on @wq for a complex
+ * @condition to become true, thus avoiding the race conditions
+ * associated with the deprecated sleep_on*() family of functions.
+ *
+ * The macros indicate their usage in their name. Unless explicitly
+ * requested to be different, the following defaults are the case:
+ * - no lock needs to be grabbed/released;
+ * - a timeout is not requested, i.e. only @condition being true
+ * will cause the macro to return; and
+ * - the sleep will be in TASK_UNINTERRUPTIBLE, i.e. signals will
+ * be ignored.
+ * If the macro name contains:
+ * lock, then @lock should be held before calling wait_event*().
+ * It is released before sleeping and grabbed after
+ * waking, saving the current IRQ mask in @flags. This lock
+ * should also be held when changing any variables
+ * affecting the condition and when waking up the process.
+ * timeout, then even if @condition is not true, but @timeout
+ * jiffies have passed, the macro will return. The number
+ * of jiffies remaining in the delay will be returned
+ * interruptible, then signals will cause the macro to return
+ * early with a return code of -ERESTARTSYS
+ * exclusive, then current is an exclusive process and must be
+ * selectively woken.
+ */
#define __wait_event(wq, condition) \
do { \
DEFINE_WAIT(__wait); \
@@ -176,6 +202,28 @@ do {
\
__wait_event(wq, condition); \
} while (0)
+#define __wait_event_lock(wq, condition, lock, flags) \
+do { \
+ DEFINE_WAIT(__wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ spin_unlock_irqrestore(lock, flags); \
+ schedule(); \
+ spin_lock_irqsave(lock, flags); \
+ } \
+ finish_wait(&wq, &__wait); \
+} while (0)
+
+#define wait_event_lock(wq, condition, lock, flags) \
+do { \
+ if (condition) \
+ break; \
+ __wait_event_lock(wq, condition, lock, flags); \
+} while (0)
+
#define __wait_event_timeout(wq, condition, ret) \
do { \
DEFINE_WAIT(__wait); \
@@ -199,6 +247,31 @@ do {
\
__ret; \
})
+#define __wait_event_timeout_lock(wq, condition, lock, flags, ret) \
+do { \
+ DEFINE_WAIT(__wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&wq, &__wait, TASK_UNINTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ spin_unlock_irqrestore(lock, flags); \
+ ret = schedule_timeout(ret); \
+ spin_lock_irqsave(lock, flags); \
+ if (!ret) \
+ break; \
+ } \
+ finish_wait(&wq, &__wait); \
+} while (0)
+
+#define wait_event_timeout_lock(wq, condition, lock, flags, timeout) \
+({ \
+ long __ret = timeout; \
+ if (!(condition)) \
+ __wait_event_timeout_lock(wq, condition, lock, flags, __ret); \
+ __ret; \
+})
+
#define __wait_event_interruptible(wq, condition, ret) \
do { \
DEFINE_WAIT(__wait); \
@@ -225,6 +298,34 @@ do {
\
__ret; \
})
+#define __wait_event_interruptible_lock(wq, condition, lock, flags, ret) \
+do { \
+ DEFINE_WAIT(__wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ if (!signal_pending(current)) { \
+ spin_unlock_irqrestore(lock, flags) \
+ schedule(); \
+ spin_lock_irqsave(lock, flags) \
+ continue; \
+ } \
+ ret = -ERESTARTSYS; \
+ break; \
+ } \
+ finish_wait(&wq, &__wait); \
+} while (0)
+
+#define wait_event_interruptible_lock(wq, condition, lock, flags) \
+({ \
+ int __ret = 0; \
+ if (!(condition)) \
+ __wait_event_interruptible_lock(wq, condition, lock, flags,
__ret); \
+ __ret; \
+})
+
#define __wait_event_interruptible_timeout(wq, condition, ret) \
do { \
DEFINE_WAIT(__wait); \
@@ -253,6 +354,36 @@ do {
\
__ret; \
})
+#define __wait_event_interruptible_timeout_lock(wq, condition, lock, flags,
ret) \
+do { \
+ DEFINE_WAIT(__wait); \
+ \
+ for (;;) { \
+ prepare_to_wait(&wq, &__wait, TASK_INTERRUPTIBLE); \
+ if (condition) \
+ break; \
+ if (!signal_pending(current)) { \
+ spin_unlock_irqrestore(lock, flags); \
+ ret = schedule_timeout(ret); \
+ spin_lock_irqsave(lock, flags); \
+ if (!ret) \
+ break; \
+ continue; \
+ } \
+ ret = -ERESTARTSYS; \
+ break; \
+ } \
+ finish_wait(&wq, &__wait); \
+} while (0)
+
+#define wait_event_interruptible_timeout_lock(wq, condition, lock, flags,
timeout) \
+({ \
+ long __ret = timeout; \
+ if (!(condition)) \
+ __wait_event_interruptible_timeout_lock(wq, condition, lock,
flags, __ret); \
+ __ret; \
+})
+
#define __wait_event_interruptible_exclusive(wq, condition, ret) \
do { \
DEFINE_WAIT(__wait); \
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
