From: Paul Clements <Paul.Clements@SteelEye.com>
To: marcelo@conectiva.com.br
Cc: linux-kernel <linux-kernel@vger.kernel.org>
Subject: [PATCH 2.4.22-pre] nbd: fix race conditions
Date: Sat, 09 Aug 2003 18:10:41 -0400 [thread overview]
Message-ID: <3F357161.7940B75@SteelEye.com> (raw)
In-Reply-To: 3F3402F7.A8986417@SteelEye.com
[-- Attachment #1: Type: text/plain, Size: 653 bytes --]
This patch is similar to one I posted yesterday for 2.6. It fixes the
following race conditions in nbd:
1) adds locking and properly orders the code in NBD_CLEAR_SOCK to
eliminate races with other code
2) adds an lo->sock check to nbd_clear_que to eliminate races between
do_nbd_request and nbd_clear_que, which resulted in the dequeuing of
active requests
3) adds an lo->sock check to NBD_DO_IT to eliminate races with
NBD_CLEAR_SOCK, which caused an Oops when "nbd-client -d" was called
Marcelo,
If we can get this into 2.4.22, that would be great. I know there's at
least one person who's consistently getting oopses with nbd.
Thanks,
Paul
[-- Attachment #2: nbd-race_fixes_2_4_21.diff --]
[-- Type: text/x-diff, Size: 2027 bytes --]
--- linux-2.4.21-PRISTINE/drivers/block/nbd.c Fri Jun 13 10:51:32 2003
+++ linux-2.4.21/drivers/block/nbd.c Sat Aug 9 13:25:49 2003
@@ -428,23 +428,24 @@ static int nbd_ioctl(struct inode *inode
return 0 ;
case NBD_CLEAR_SOCK:
+ error = 0;
+ down(&lo->tx_lock);
+ lo->sock = NULL;
+ up(&lo->tx_lock);
+ spin_lock(&lo->queue_lock);
+ file = lo->file;
+ lo->file = NULL;
+ spin_unlock(&lo->queue_lock);
nbd_clear_que(lo);
spin_lock(&lo->queue_lock);
if (!list_empty(&lo->queue_head)) {
- spin_unlock(&lo->queue_lock);
- printk(KERN_ERR "nbd: Some requests are in progress -> can not turn off.\n");
- return -EBUSY;
- }
- file = lo->file;
- if (!file) {
- spin_unlock(&lo->queue_lock);
- return -EINVAL;
+ printk(KERN_ERR "nbd: disconnect: some requests are in progress -> please try again.\n");
+ error = -EBUSY;
}
- lo->file = NULL;
- lo->sock = NULL;
spin_unlock(&lo->queue_lock);
- fput(file);
- return 0;
+ if (file)
+ fput(file);
+ return error;
case NBD_SET_SOCK:
if (lo->file)
return -EBUSY;
@@ -491,9 +492,12 @@ static int nbd_ioctl(struct inode *inode
* there should be a more generic interface rather than
* calling socket ops directly here */
down(&lo->tx_lock);
- printk(KERN_WARNING "nbd: shutting down socket\n");
- lo->sock->ops->shutdown(lo->sock, SEND_SHUTDOWN|RCV_SHUTDOWN);
- lo->sock = NULL;
+ if (lo->sock) {
+ printk(KERN_WARNING "nbd: shutting down socket\n");
+ lo->sock->ops->shutdown(lo->sock,
+ SEND_SHUTDOWN|RCV_SHUTDOWN);
+ lo->sock = NULL;
+ }
up(&lo->tx_lock);
spin_lock(&lo->queue_lock);
file = lo->file;
@@ -505,6 +509,13 @@ static int nbd_ioctl(struct inode *inode
fput(file);
return lo->harderror;
case NBD_CLEAR_QUE:
+ down(&lo->tx_lock);
+ if (lo->sock) {
+ up(&lo->tx_lock);
+ return 0; /* probably should be error, but that would
+ * break "nbd-client -d", so just return 0 */
+ }
+ up(&lo->tx_lock);
nbd_clear_que(lo);
return 0;
#ifdef PARANOIA
next prev parent reply other threads:[~2003-08-09 22:12 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-08-05 16:51 [PATCH] 2.6.0 NBD driver: remove send/recieve race for request Lou Langholtz
2003-08-05 19:37 ` Paul Clements
2003-08-05 22:48 ` Lou Langholtz
2003-08-06 0:51 ` Paul Clements
2003-08-06 7:34 ` Lou Langholtz
2003-08-08 5:02 ` Paul Clements
2003-08-08 5:27 ` Andrew Morton
2003-08-08 17:05 ` Paul Clements
2003-08-08 6:30 ` Lou Langholtz
2003-08-08 6:43 ` Andrew Morton
2003-08-08 6:59 ` Jens Axboe
2003-08-08 15:00 ` Paul Clements
2003-08-25 9:58 ` Jens Axboe
2003-08-08 16:47 ` Paul Clements
2003-08-08 20:07 ` [PATCH 2.6.0-test2-mm] nbd: fix send/receive/shutdown/disconnect races Paul Clements
2003-08-09 22:10 ` Paul Clements [this message]
[not found] <iKef.8c1.15@gated-at.bofh.it>
2003-08-10 17:06 ` [PATCH 2.4.22-pre] nbd: fix race conditions Peter T. Breuer
2003-08-10 18:15 ` Paul Clements
2003-08-11 18:52 ` Marcelo Tosatti
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