Re: [PATCH] Fix soft lockup with iSeries viocd driver

2007-03-01 Thread Stephen Rothwell 
On Thu, 1 Mar 2007 00:37:48 -0800 Andrew Morton <[EMAIL PROTECTED]> wrote:
>
> On Thu, 1 Mar 2007 14:56:40 +1100 [EMAIL PROTECTED] (Tony Breeds) wrote:
>
> > From: Tony Breeds <[EMAIL PROTECTED]>
> >
> > Fix soft lockup with iSeries viocd driver, caused by eventually calling
> > end_that_request_first() with nr_bytes 0.
> >
> > The lockup is triggered by hald, interrogating the device.
> >
>
> What causes the lockup, and how does this patch fix it?

Some versions of hald do an SG_IO ioctl on the viocd device which becomes
a request with hard_nr_sectors and hard_cur_sectors set to zero.  Passing
zero as the number of sectors to end_request() (which calls
end_that_request_first()) causes an infinite loop when the bio is being
freed.  This patch makes sure that the zero is never passed. It only
requires some number larger the the request size the terminate the loop.

--
Cheers,
Stephen Rothwell[EMAIL PROTECTED]
http://www.canb.auug.org.au/~sfr/


pgp7H2Qxz0Ee8.pgp
Description: PGP signature

Re: [PATCH] Fix soft lockup with iSeries viocd driver

2007-03-01 Thread Andrew Morton 
On Thu, 1 Mar 2007 14:56:40 +1100 [EMAIL PROTECTED] (Tony Breeds) wrote:

> From: Tony Breeds <[EMAIL PROTECTED]>
> 
> Fix soft lockup with iSeries viocd driver, caused by eventually calling
> end_that_request_first() with nr_bytes 0.
> 
> The lockup is triggered by hald, interrogating the device.
> 

What causes the lockup, and how does this patch fix it?

> 
> Index: linux-2.6.20-rc5/drivers/cdrom/viocd.c
> ===
> --- linux-2.6.20-rc5.orig/drivers/cdrom/viocd.c
> +++ linux-2.6.20-rc5/drivers/cdrom/viocd.c
> @@ -376,6 +376,25 @@ static int send_request(struct request *
> return 0;
>  }
>  
> +static void viocd_end_request(struct request *req, int uptodate)
> +{
> +   int nsectors = req->hard_nr_sectors;

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Re: [PATCH] Fix soft lockup with iSeries viocd driver

2007-03-01 Thread Andrew Morton 
On Thu, 1 Mar 2007 14:56:40 +1100 [EMAIL PROTECTED] (Tony Breeds) wrote:

 From: Tony Breeds [EMAIL PROTECTED]
 
 Fix soft lockup with iSeries viocd driver, caused by eventually calling
 end_that_request_first() with nr_bytes 0.
 
 The lockup is triggered by hald, interrogating the device.
 

What causes the lockup, and how does this patch fix it?

 
 Index: linux-2.6.20-rc5/drivers/cdrom/viocd.c
 ===
 --- linux-2.6.20-rc5.orig/drivers/cdrom/viocd.c
 +++ linux-2.6.20-rc5/drivers/cdrom/viocd.c
 @@ -376,6 +376,25 @@ static int send_request(struct request *
 return 0;
  }
  
 +static void viocd_end_request(struct request *req, int uptodate)
 +{
 +   int nsectors = req-hard_nr_sectors;

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Re: [PATCH] Fix soft lockup with iSeries viocd driver

2007-03-01 Thread Stephen Rothwell 
On Thu, 1 Mar 2007 00:37:48 -0800 Andrew Morton [EMAIL PROTECTED] wrote:

 On Thu, 1 Mar 2007 14:56:40 +1100 [EMAIL PROTECTED] (Tony Breeds) wrote:

  From: Tony Breeds [EMAIL PROTECTED]
 
  Fix soft lockup with iSeries viocd driver, caused by eventually calling
  end_that_request_first() with nr_bytes 0.
 
  The lockup is triggered by hald, interrogating the device.
 

 What causes the lockup, and how does this patch fix it?

Some versions of hald do an SG_IO ioctl on the viocd device which becomes
a request with hard_nr_sectors and hard_cur_sectors set to zero.  Passing
zero as the number of sectors to end_request() (which calls
end_that_request_first()) causes an infinite loop when the bio is being
freed.  This patch makes sure that the zero is never passed. It only
requires some number larger the the request size the terminate the loop.

--
Cheers,
Stephen Rothwell[EMAIL PROTECTED]
http://www.canb.auug.org.au/~sfr/


pgp7H2Qxz0Ee8.pgp
Description: PGP signature

[PATCH] Fix soft lockup with iSeries viocd driver

2007-02-28 Thread Tony Breeds 
From: Tony Breeds <[EMAIL PROTECTED]>

Fix soft lockup with iSeries viocd driver, caused by eventually calling
end_that_request_first() with nr_bytes 0.

The lockup is triggered by hald, interrogating the device.

Signed-off-by: Tony Breeds <[EMAIL PROTECTED]>
Signed-off-by: Jens Axboe <[EMAIL PROTECTED]>

---
 viocd.c |   27 +++
 1 file changed, 23 insertions(+), 4 deletions(-)

Index: linux-2.6.20-rc5/drivers/cdrom/viocd.c
===
--- linux-2.6.20-rc5.orig/drivers/cdrom/viocd.c
+++ linux-2.6.20-rc5/drivers/cdrom/viocd.c
@@ -376,6 +376,25 @@ static int send_request(struct request *
return 0;
 }
 
+static void viocd_end_request(struct request *req, int uptodate)
+{
+   int nsectors = req->hard_nr_sectors;
+
+   /*
+* Make sure it's fully ended, and ensure that we process
+* at least one sector.
+*/
+   if (blk_pc_request(req))
+   nsectors = (req->data_len + 511) >> 9;
+   if (!nsectors)
+   nsectors = 1;
+
+   if (end_that_request_first(req, uptodate, nsectors))
+   BUG();
+   add_disk_randomness(req->rq_disk);
+   blkdev_dequeue_request(req);
+   end_that_request_last(req, uptodate);
+}
 
 static int rwreq;
 
@@ -385,11 +404,11 @@ static void do_viocd_request(request_que
 
while ((rwreq == 0) && ((req = elv_next_request(q)) != NULL)) {
if (!blk_fs_request(req))
-   end_request(req, 0);
+   viocd_end_request(req, 0);
else if (send_request(req) < 0) {
printk(VIOCD_KERN_WARNING
"unable to send message to OS/400!");
-   end_request(req, 0);
+   viocd_end_request(req, 0);
} else
rwreq++;
}
@@ -601,9 +620,9 @@ return_complete:
"with rc %d:0x%04X: %s\n",
req, event->xRc,
bevent->sub_result, err->msg);
-   end_request(req, 0);
+   viocd_end_request(req, 0);
} else
-   end_request(req, 1);
+   viocd_end_request(req, 1);
 
/* restart handling of incoming requests */
spin_unlock_irqrestore(_reqlock, flags);





Yours Tony

  linux.conf.auhttp://linux.conf.au/ || http://lca2008.linux.org.au/
  Jan 28 - Feb 02 2008 The Australian Linux Technical Conference!



Yours Tony

  linux.conf.auhttp://linux.conf.au/ || http://lca2008.linux.org.au/
  Jan 28 - Feb 02 2008 The Australian Linux Technical Conference!

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[PATCH] Fix soft lockup with iSeries viocd driver

2007-02-28 Thread Tony Breeds 
From: Tony Breeds [EMAIL PROTECTED]

Fix soft lockup with iSeries viocd driver, caused by eventually calling
end_that_request_first() with nr_bytes 0.

The lockup is triggered by hald, interrogating the device.

Signed-off-by: Tony Breeds [EMAIL PROTECTED]
Signed-off-by: Jens Axboe [EMAIL PROTECTED]

---
 viocd.c |   27 +++
 1 file changed, 23 insertions(+), 4 deletions(-)

Index: linux-2.6.20-rc5/drivers/cdrom/viocd.c
===
--- linux-2.6.20-rc5.orig/drivers/cdrom/viocd.c
+++ linux-2.6.20-rc5/drivers/cdrom/viocd.c
@@ -376,6 +376,25 @@ static int send_request(struct request *
return 0;
 }
 
+static void viocd_end_request(struct request *req, int uptodate)
+{
+   int nsectors = req-hard_nr_sectors;
+
+   /*
+* Make sure it's fully ended, and ensure that we process
+* at least one sector.
+*/
+   if (blk_pc_request(req))
+   nsectors = (req-data_len + 511)  9;
+   if (!nsectors)
+   nsectors = 1;
+
+   if (end_that_request_first(req, uptodate, nsectors))
+   BUG();
+   add_disk_randomness(req-rq_disk);
+   blkdev_dequeue_request(req);
+   end_that_request_last(req, uptodate);
+}
 
 static int rwreq;
 
@@ -385,11 +404,11 @@ static void do_viocd_request(request_que
 
while ((rwreq == 0)  ((req = elv_next_request(q)) != NULL)) {
if (!blk_fs_request(req))
-   end_request(req, 0);
+   viocd_end_request(req, 0);
else if (send_request(req)  0) {
printk(VIOCD_KERN_WARNING
unable to send message to OS/400!);
-   end_request(req, 0);
+   viocd_end_request(req, 0);
} else
rwreq++;
}
@@ -601,9 +620,9 @@ return_complete:
with rc %d:0x%04X: %s\n,
req, event-xRc,
bevent-sub_result, err-msg);
-   end_request(req, 0);
+   viocd_end_request(req, 0);
} else
-   end_request(req, 1);
+   viocd_end_request(req, 1);
 
/* restart handling of incoming requests */
spin_unlock_irqrestore(viocd_reqlock, flags);





Yours Tony

  linux.conf.auhttp://linux.conf.au/ || http://lca2008.linux.org.au/
  Jan 28 - Feb 02 2008 The Australian Linux Technical Conference!



Yours Tony

  linux.conf.auhttp://linux.conf.au/ || http://lca2008.linux.org.au/
  Jan 28 - Feb 02 2008 The Australian Linux Technical Conference!

-
To unsubscribe from this list: send the line unsubscribe linux-kernel in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html
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