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Message-ID: <20070227234234.GQ4575@bakeyournoodle.com>
Date: Wed, 28 Feb 2007 10:42:34 +1100
From: tony@...eyournoodle.com (Tony Breeds)
To: Jens Axboe <jens.axboe@...cle.com>
Cc: Stephen Rothwell <sfr@...b.auug.org.au>,
Linux Kernel ML <linux-kernel@...r.kernel.org>
Subject: Re: Fix soft lockup with iSeries viocd driver
On Tue, Feb 27, 2007 at 03:33:34PM +0100, Jens Axboe wrote:
> It looks ok (better than end_request()), though it would still be nice
> to properly end requests. See the recent thread on the lguest block
> driver.
Hi Jens,
I read through the lguest thread and came up with the patch
below, I hope I understood correctly. We still need to do the check to
make sure we ask for at least one sector to be processed in
end_that_request_first(), as the request that triggers the lockup here
(an sg_io ioctl in this case), has both req->hard_nr_sectors and
req->hard_cur_sectors = 0.
From: Tony Breeds <tony@...eyournoodle.com>
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 <tony@...eyournoodle.com>
---
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.au http://linux.conf.au/ || http://lca2008.linux.org.au/
Jan 28 - Feb 02 2008 The Australian Linux Technical Conference!
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