PERFORCE change 183909 for review

[Ken Merry]

http://p4web.freebsd.org/@@183909?ac=10

Change 183909 by ken at ken.spectra.vm-freebsd on 2010/09/17 21:50:13

	Fix a couple of mps problems.
	
	When the driver is completely saturated with commands (1024 in the
	case of the SAS2008 in my test system), I/O stops.  If we tell CAM
	that we have one less command slot than we have actually allocated,
	everything works fine.  We also need a few extra command slots to
	allow for aborts and other task management commands to be sent down.
	
	This needs more investigation to determine the root cause, but for
	now this fixes things in my testing.
	
	mps.c:		Change a printf() to mps_printf().
	
	mps_sas.c:	Subtract 5 command slots when we tell CAM how many
			commands we can handle.
	
			Add some commented-out logic to print the contents
			the CDBs for timed-out commands.  This can help
			in debugging devices that are timing out.  This
			will be uncommented once I bring some CAM changes
			in.
	
	Reported by:	Andrew Boyer <aboyer at averesystems dot com>

Affected files ...

.. //depot/projects/mps/src/sys/dev/mps/mps.c#2 edit
.. //depot/projects/mps/src/sys/dev/mps/mps_sas.c#4 edit

Differences ...

==== //depot/projects/mps/src/sys/dev/mps/mps.c#2 (text+ko) ====

@@ -1416,7 +1416,7 @@
 			chain = mps_alloc_chain(sc);
 			if (chain == NULL) {
 				/* Resource shortage, roll back! */
-				printf("out of chain frames\n");
+				mps_printf(sc, "out of chain frames\n");
 				return;
 			}
 

==== //depot/projects/mps/src/sys/dev/mps/mps_sas.c#4 (text+ko) ====

@@ -596,6 +596,7 @@
 {
 	struct mpssas_softc *sassc;
 	int error = 0;
+	int num_sim_reqs;
 
 	mps_dprint(sc, MPS_TRACE, "%s\n", __func__);
 
@@ -605,15 +606,30 @@
 	sc->sassc = sassc;
 	sassc->sc = sc;
 
-	if ((sassc->devq = cam_simq_alloc(sc->num_reqs)) == NULL) {
+	/*
+	 * Tell CAM that we can handle 5 fewer requests than we have
+	 * allocated.  If we allow the full number of requests, all I/O
+	 * will halt when we run out of resources.  Things work fine with
+	 * just 1 less request slot given to CAM than we have allocated.
+	 * We also need a couple of extra commands so that we can send down
+	 * abort, reset, etc. requests when commands time out.  Otherwise
+	 * we could wind up in a situation with sc->num_reqs requests down
+	 * on the card and no way to send an abort.
+	 *
+	 * XXX KDM need to figure out why I/O locks up if all commands are
+	 * used.
+	 */
+	num_sim_reqs = sc->num_reqs - 5;
+
+	if ((sassc->devq = cam_simq_alloc(num_sim_reqs)) == NULL) {
 		mps_dprint(sc, MPS_FAULT, "Cannot allocate SIMQ\n");
 		error = ENOMEM;
 		goto out;
 	}
 
 	sassc->sim = cam_sim_alloc(mpssas_action, mpssas_poll, "mps", sassc,
-	    device_get_unit(sc->mps_dev), &sc->mps_mtx, sc->num_reqs, sc->num_reqs,
-	    sassc->devq);
+	    device_get_unit(sc->mps_dev), &sc->mps_mtx, num_sim_reqs,
+	    num_sim_reqs, sassc->devq);
 	if (sassc->sim == NULL) {
 		mps_dprint(sc, MPS_FAULT, "Cannot allocate SIM\n");
 		error = EINVAL;
@@ -930,6 +946,9 @@
 	struct mps_softc *sc;
 	struct mps_command *cm;
 	struct mpssas_target *targ;
+#if 0
+	char cdb_str[(SCSI_MAX_CDBLEN * 3) + 1];
+#endif
 
 	cm = (struct mps_command *)data;
 	sc = cm->cm_sc;
@@ -954,6 +973,22 @@
 
 	xpt_print(ccb->ccb_h.path, "SCSI command timeout on device handle "
 		  "0x%04x SMID %d\n", targ->handle, cm->cm_desc.Default.SMID);
+	/*
+	 * XXX KDM this is useful for debugging purposes, but the existing
+	 * scsi_op_desc() implementation can't handle a NULL value for
+	 * inq_data.  So this will remain commented out until I bring in
+	 * those changes as well.
+	 */
+#if 0
+	xpt_print(ccb->ccb_h.path, "Timed out command: %s. CDB %s\n",
+		  scsi_op_desc((ccb->ccb_h.flags & CAM_CDB_POINTER) ?
+		  		ccb->csio.cdb_io.cdb_ptr[0] :
+				ccb->csio.cdb_io.cdb_bytes[0], NULL),
+		  scsi_cdb_string((ccb->ccb_h.flags & CAM_CDB_POINTER) ?
+				   ccb->csio.cdb_io.cdb_ptr :
+				   ccb->csio.cdb_io.cdb_bytes, cdb_str,
+		  		   sizeof(cdb_str)));
+#endif
 
 	/* Inform CAM about the timeout and that recovery is starting. */
 #if 0