Re: [2.4.21]: nbd ksymoops-report

[Paul Clements <Paul.Clements@SteelEye.com>]

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Paul Clements wrote:
> 
> Paul Clements wrote:
> >
> > On Thu, 7 Aug 2003, Bernd Schubert wrote:
> >
> > > every time when nbd-client disconnects a nbd-device the decoded oops
> > > from below will happen.
> > > This only happens after we upgraded from 2.4.20 to 2.4.21,
> > > so I guess the backported update from 2.5.50 causes this.

[snip]

> > Would you be willing to test a patch against 2.4.21?
> 
> If you're willing to test the attached patch, I'd be grateful. Otherwise
> I'll test it in the next few days and forward on to Marcelo...

OK, the previous patch didn't quite do it. The attached should work (I
got a chance to test it, finally). 

Thanks,
Paul

[-- Attachment #2: nbd_sock_null_race_fix_2_4_21-2.diff --]
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diff -up linux-2.4.21-PRISTINE/drivers/block/nbd.c linux-2.4.21/drivers/block/nbd.c
--- linux-2.4.21-PRISTINE/drivers/block/nbd.c	2003-06-13 10:51:32.000000000 -0400
+++ linux-2.4.21/drivers/block/nbd.c	2003-08-07 18:05:39.000000000 -0400
@@ -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;
+			printk(KERN_ERR "nbd: disconnect: some requests are in progress -> please try again.\n");
+			error = -EBUSY;
 		}
-		file = lo->file;
-		if (!file) {
-			spin_unlock(&lo->queue_lock);
-			return -EINVAL;
-		}
-		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;
Common subdirectories: linux-2.4.21-PRISTINE/drivers/block/paride and linux-2.4.21/drivers/block/paride