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Message-Id: <20080115095755.1172.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date: Tue, 15 Jan 2008 09:59:12 +0900
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: linux-mm@...ck.org, linux-kernel@...r.kernel.org
Cc: kosaki.motohiro@...fujitsu.com,
Marcelo Tosatti <marcelo@...ck.org>,
Daniel Spang <daniel.spang@...il.com>,
Rik van Riel <riel@...hat.com>,
Andrew Morton <akpm@...ux-foundation.org>
Subject: [RFC][PATCH 1/5] introduce poll_wait_exclusive() new API
There are 2 way of adding item to wait_queue,
1. add_wait_queue()
2. add_wait_queue_exclusive()
and add_wait_queue_exclusive() is very useful API.
unforunately, poll_wait_exclusive() against poll_wait() doesn't exist.
it means there is no way that wake up only 1 process where polled.
wake_up() is wake up all sleeping process by poll_wait(), not 1 process.
this patch introduce poll_wait_exclusive() new API for allow wake up only 1 process.
<example of usage>
unsigned int kosaki_poll(struct file *file,
struct poll_table_struct *wait)
{
poll_wait_exclusive(file, &kosaki_wait_queue, wait);
if (data_exist)
return POLLIN | POLLRDNORM;
return 0;
}
Signed-off-by: Marcelo Tosatti <marcelo@...ck.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
---
fs/eventpoll.c | 7 +++++--
fs/select.c | 9 ++++++---
include/linux/poll.h | 11 +++++++++--
3 files changed, 20 insertions(+), 7 deletions(-)
Index: linux-2.6.24-rc6-memnotify/fs/eventpoll.c
===================================================================
--- linux-2.6.24-rc6-memnotify.orig/fs/eventpoll.c 2007-12-30 02:08:58.000000000 +0900
+++ linux-2.6.24-rc6-memnotify/fs/eventpoll.c 2007-12-30 07:10:46.000000000 +0900
@@ -676,7 +676,7 @@ out_unlock:
* target file wakeup lists.
*/
static void ep_ptable_queue_proc(struct file *file, wait_queue_head_t *whead,
- poll_table *pt)
+ poll_table *pt, int exclusive)
{
struct epitem *epi = ep_item_from_epqueue(pt);
struct eppoll_entry *pwq;
@@ -685,7 +685,10 @@ static void ep_ptable_queue_proc(struct
init_waitqueue_func_entry(&pwq->wait, ep_poll_callback);
pwq->whead = whead;
pwq->base = epi;
- add_wait_queue(whead, &pwq->wait);
+ if (exclusive)
+ add_wait_queue_exclusive(whead, &pwq->wait);
+ else
+ add_wait_queue(whead, &pwq->wait);
list_add_tail(&pwq->llink, &epi->pwqlist);
epi->nwait++;
} else {
Index: linux-2.6.24-rc6-memnotify/fs/select.c
===================================================================
--- linux-2.6.24-rc6-memnotify.orig/fs/select.c 2007-12-30 02:09:00.000000000 +0900
+++ linux-2.6.24-rc6-memnotify/fs/select.c 2007-12-30 02:34:05.000000000 +0900
@@ -48,7 +48,7 @@ struct poll_table_page {
* poll table.
*/
static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
- poll_table *p);
+ poll_table *p, int exclusive);
void poll_initwait(struct poll_wqueues *pwq)
{
@@ -117,7 +117,7 @@ static struct poll_table_entry *poll_get
/* Add a new entry */
static void __pollwait(struct file *filp, wait_queue_head_t *wait_address,
- poll_table *p)
+ poll_table *p, int exclusive)
{
struct poll_table_entry *entry = poll_get_entry(p);
if (!entry)
@@ -126,7 +126,10 @@ static void __pollwait(struct file *filp
entry->filp = filp;
entry->wait_address = wait_address;
init_waitqueue_entry(&entry->wait, current);
- add_wait_queue(wait_address, &entry->wait);
+ if (exclusive)
+ add_wait_queue_exclusive(wait_address, &entry->wait);
+ else
+ add_wait_queue(wait_address, &entry->wait);
}
#define FDS_IN(fds, n) (fds->in + n)
Index: linux-2.6.24-rc6-memnotify/include/linux/poll.h
===================================================================
--- linux-2.6.24-rc6-memnotify.orig/include/linux/poll.h 2007-12-30 02:09:16.000000000 +0900
+++ linux-2.6.24-rc6-memnotify/include/linux/poll.h 2007-12-30 02:41:35.000000000 +0900
@@ -28,7 +28,8 @@ struct poll_table_struct;
/*
* structures and helpers for f_op->poll implementations
*/
-typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *, struct poll_table_struct *);
+typedef void (*poll_queue_proc)(struct file *, wait_queue_head_t *,
+ struct poll_table_struct *, int);
typedef struct poll_table_struct {
poll_queue_proc qproc;
@@ -37,7 +38,13 @@ typedef struct poll_table_struct {
static inline void poll_wait(struct file * filp, wait_queue_head_t * wait_address, poll_table *p)
{
if (p && wait_address)
- p->qproc(filp, wait_address, p);
+ p->qproc(filp, wait_address, p, 0);
+}
+
+static inline void poll_wait_exclusive(struct file *filp, wait_queue_head_t *wait_address, poll_table *p)
+{
+ if (p && wait_address)
+ p->qproc(filp, wait_address, p, 1);
}
static inline void init_poll_funcptr(poll_table *pt, poll_queue_proc qproc)
--
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