by Hello Linus,
This patch against 2.5.22 adds support for wait queue function
callbacks, which are used by aio to build async read / write
operations on top of existing wait queues at points that would
normally block a process. Comments?
-ben
--
"You will be reincarnated as a toad; and you will be much happier."
:r ~/patches/v2.5/v2.5.22-waitqueue-func.diff
diff -urN v2.5.22/include/linux/wait.h wq-func-v2.5.22.diff/include/linux/wait.h
--- v2.5.22/include/linux/wait.h Mon Jun 10 21:41:10 2002
#include <asm/page.h>
#include <asm/processor.h>
+typedef struct __wait_queue wait_queue_t;
+typedef void (*wait_queue_func_t)(wait_queue_t *wait);
+
struct __wait_queue {
unsigned int flags;
#define WQ_FLAG_EXCLUSIVE 0x01
struct task_struct * task;
+ wait_queue_func_t func;
struct list_head task_list;
};
-typedef struct __wait_queue wait_queue_t;
struct __wait_queue_head {
#define __WAITQUEUE_INITIALIZER(name, tsk) { \
task: tsk, \
+ func: NULL, \
task_list: { NULL, NULL } }
{
q->flags = 0;
q->task = p;
+ q->func = NULL;
+}
+
+static inline void init_waitqueue_func_entry(wait_queue_t *q,
+ wait_queue_func_t func)
+{
+ q->flags = 0;
+ q->task = NULL;
+ q->func = func;
}
list_del(&old->task_list);
}
+#define add_wait_queue_cond(q, wait, cond) \
+ ({ \
+ unsigned long flags; \
+ int _raced = 0; \
+ wq_write_lock_irqsave(&(q)->lock, flags); \
+ (wait)->flags = 0; \
+ __add_wait_queue((q), (wait)); \
+ rmb(); \
+ if (!(cond)) { \
+ _raced = 1; \
+ __remove_wait_queue((q), (wait)); \
+ } \
+ wq_write_unlock_irqrestore(&(q)->lock, flags); \
+ _raced; \
+ })
+
#endif /* __KERNEL__ */
#endif
diff -urN v2.5.22/kernel/sched.c wq-func-v2.5.22.diff/kernel/sched.c
--- v2.5.22/kernel/sched.c Mon Jun 17 15:41:42 2002
*/
static inline void __wake_up_common(wait_queue_head_t *q, unsigned int mode, int nr_exclusive, int sync)
{
- struct list_head *tmp;
+ struct list_head *tmp, *next;
unsigned int state;
wait_queue_t *curr;
task_t *p;
- list_for_each(tmp, &q->task_list) {
+ list_for_each_safe(tmp, next, &q->task_list) {
+ wait_queue_func_t func;
curr = list_entry(tmp, wait_queue_t, task_list);
+ func = curr->func;
+ if (func) {
+ unsigned flags = curr->flags;
+ func(curr);
+ if ((flags & WQ_FLAG_EXCLUSIVE) && !--nr_exclusive)
+ break;
+ continue;
+ }
p = curr->task;
state = p->state;
if ((state & mode) && try_to_wake_up(p, sync) &&
-
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