[ PATCH 3/4 ] mpt fusion prevent DV deadlock

[Bernd Schubert <bs@q-leap.de>]

The mpt fusion driver will do a domain revalidation on an ioc reset, but this
DV might cause a live deadlock. The problem has been entirely analyzed in
this thread http://marc.info/?t=118039577800004, but so far none of the 
suggested
solutions has been implemented.
This patch simply disables the domain revalidation, if it does know it 
will run into the deadlock.

Signed-off-by: Bernd Schubert <bs@q-leap.de>

 drivers/message/fusion/mptspi.c |   12 ++++++++++++
 1 file changed, 12 insertions(+)

Index: linux-2.6.26/drivers/message/fusion/mptspi.c
===================================================================
--- linux-2.6.26.orig/drivers/message/fusion/mptspi.c
+++ linux-2.6.26/drivers/message/fusion/mptspi.c
@@ -672,12 +672,24 @@ static void mptspi_dv_device(struct _MPT
 {
 	VirtTarget *vtarget = scsi_target(sdev)->hostdata;
 	MPT_ADAPTER *ioc = hd->ioc;
+	unsigned long nr_requests = sdev->request_queue->nr_requests;
+	struct request_list *rl = &sdev->request_queue->rq;
 
 	/* no DV on RAID devices */
 	if (sdev->channel == 0 &&
 	    mptspi_is_raid(hd, sdev->id))
 		return;
 
+	if (rl->count[0] + 1 >= nr_requests
+	||  rl->count[1] + 1 >= nr_requests) {
+		/* we must NOT do a DV after an error recovery, when we
+		 * don't have left a space in the request list, since
+		 * this will cause a live dead lock */
+		starget_printk(KERN_INFO, scsi_target(sdev), MYIOC_s_FMT
+		    "Skipping DV, to prevent dead lock!\n", ioc->name);
+		return;
+	}
+
 	/* If this is a piece of a RAID, then quiesce first */
 	if (sdev->channel == 1 &&
 	    mptscsih_quiesce_raid(hd, 1, vtarget->channel, vtarget->id) < 0) {



-- 
Bernd Schubert
Q-Leap Networks GmbH