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Message-ID: <20070810160512.24698.12317.stgit@warthog.cambridge.redhat.com>
Date: Fri, 10 Aug 2007 17:05:12 +0100
From: David Howells <dhowells@...hat.com>
To: torvalds@...l.org, akpm@...l.org, steved@...hat.com,
trond.myklebust@....uio.no
Cc: linux-fsdevel@...r.kernel.org, linux-cachefs@...hat.com,
nfsv4@...ux-nfs.org, linux-kernel@...r.kernel.org,
selinux@...ho.nsa.gov
Subject: [PATCH 03/16] FS-Cache: Provide an add_wait_queue_tail() function
[try #3]
Provide an add_wait_queue_tail() function to add a waiter to the back of a
wait queue instead of the front.
Signed-off-by: David Howells <dhowells@...hat.com>
---
include/linux/wait.h | 1 +
kernel/wait.c | 18 ++++++++++++++++++
2 files changed, 19 insertions(+), 0 deletions(-)
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 0e68628..4cae7db 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -118,6 +118,7 @@ static inline int waitqueue_active(wait_queue_head_t *q)
#define is_sync_wait(wait) (!(wait) || ((wait)->private))
extern void FASTCALL(add_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
+extern void FASTCALL(add_wait_queue_tail(wait_queue_head_t *q, wait_queue_t * wait));
extern void FASTCALL(add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t * wait));
extern void FASTCALL(remove_wait_queue(wait_queue_head_t *q, wait_queue_t * wait));
diff --git a/kernel/wait.c b/kernel/wait.c
index 444ddbf..7acc9cc 100644
--- a/kernel/wait.c
+++ b/kernel/wait.c
@@ -29,6 +29,24 @@ void fastcall add_wait_queue(wait_queue_head_t *q, wait_queue_t *wait)
}
EXPORT_SYMBOL(add_wait_queue);
+/**
+ * add_wait_queue_tail - Add a waiter to the back of a waitqueue
+ * @q: the wait queue to append the waiter to
+ * @wait: the waiter to be queued
+ *
+ * Add a waiter to the back of a waitqueue so that it gets woken up last.
+ */
+void fastcall add_wait_queue_tail(wait_queue_head_t *q, wait_queue_t *wait)
+{
+ unsigned long flags;
+
+ wait->flags &= ~WQ_FLAG_EXCLUSIVE;
+ spin_lock_irqsave(&q->lock, flags);
+ __add_wait_queue_tail(q, wait);
+ spin_unlock_irqrestore(&q->lock, flags);
+}
+EXPORT_SYMBOL(add_wait_queue_tail);
+
void fastcall add_wait_queue_exclusive(wait_queue_head_t *q, wait_queue_t *wait)
{
unsigned long flags;
-
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