[patch] v2.5.22 - add wait queue function callback support

Benjamin LaHaise (bcrl@redhat.com)
Mon, 17 Jun 2002 16:14:34 -0400


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 +++ wq-func-v2.5.22.diff/include/linux/wait.h Mon Jun 17 15:53:25 2002 @@ -19,13 +19,16 @@ #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 { spinlock_t lock; @@ -40,6 +43,7 @@ #define __WAITQUEUE_INITIALIZER(name, tsk) { \ task: tsk, \ + func: NULL, \ task_list: { NULL, NULL } } #define DECLARE_WAITQUEUE(name, tsk) \ @@ -62,6 +66,15 @@ { 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; } static inline int waitqueue_active(wait_queue_head_t *q) @@ -89,6 +102,22 @@ 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 +++ wq-func-v2.5.22.diff/kernel/sched.c Mon Jun 17 16:00:03 2002 @@ -916,13 +916,22 @@ */ 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) && - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/