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Date:      Tue, 23 Oct 2012 15:31:50 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-9@freebsd.org
Subject:   svn commit: r241944 - stable/9/sys/cam
Message-ID:  <201210231531.q9NFVodf098293@svn.freebsd.org>
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Author: mav
Date: Tue Oct 23 15:31:50 2012
New Revision: 241944
URL: http://svn.freebsd.org/changeset/base/241944

Log:
  MFC r241504:
  Fix XPT_DEBUG paths operations locking:
   - Extend the lock to cover xpt_path_release() for the new path.
   - While xpt_action() is called while holding right SIM lock for the new
     bus, the old path release may require different SIM lock. So we have
     to temporary drop the new lock and get the old one.

Modified:
  stable/9/sys/cam/cam_xpt.c
Directory Properties:
  stable/9/sys/   (props changed)

Modified: stable/9/sys/cam/cam_xpt.c
==============================================================================
--- stable/9/sys/cam/cam_xpt.c	Tue Oct 23 15:27:32 2012	(r241943)
+++ stable/9/sys/cam/cam_xpt.c	Tue Oct 23 15:31:50 2012	(r241944)
@@ -533,9 +533,9 @@ xptioctl(struct cdev *dev, u_long cmd, c
 			xpt_merge_ccb(&ccb, inccb);
 			ccb.ccb_h.cbfcnp = xptdone;
 			xpt_action(&ccb);
-			CAM_SIM_UNLOCK(bus->sim);
 			bcopy(&ccb, inccb, sizeof(union ccb));
 			xpt_free_path(ccb.ccb_h.path);
+			CAM_SIM_UNLOCK(bus->sim);
 			break;
 
 		}
@@ -2981,34 +2981,42 @@ xpt_action_default(union ccb *start_ccb)
 		break;
 	}
 	case XPT_DEBUG: {
+		struct cam_path *oldpath;
+		struct cam_sim *oldsim;
+
 		/* Check that all request bits are supported. */
 		if (start_ccb->cdbg.flags & ~(CAM_DEBUG_COMPILE)) {
 			start_ccb->ccb_h.status = CAM_FUNC_NOTAVAIL;
 			break;
 		}
 
-		cam_dflags = start_ccb->cdbg.flags;
+		cam_dflags = CAM_DEBUG_NONE;
 		if (cam_dpath != NULL) {
-			xpt_free_path(cam_dpath);
+			/* To release the old path we must hold proper lock. */
+			oldpath = cam_dpath;
 			cam_dpath = NULL;
+			oldsim = xpt_path_sim(oldpath);
+			CAM_SIM_UNLOCK(xpt_path_sim(start_ccb->ccb_h.path));
+			CAM_SIM_LOCK(oldsim);
+			xpt_free_path(oldpath);
+			CAM_SIM_UNLOCK(oldsim);
+			CAM_SIM_LOCK(xpt_path_sim(start_ccb->ccb_h.path));
 		}
-		if (cam_dflags != CAM_DEBUG_NONE) {
+		if (start_ccb->cdbg.flags != CAM_DEBUG_NONE) {
 			if (xpt_create_path(&cam_dpath, xpt_periph,
 					    start_ccb->ccb_h.path_id,
 					    start_ccb->ccb_h.target_id,
 					    start_ccb->ccb_h.target_lun) !=
 					    CAM_REQ_CMP) {
 				start_ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
-				cam_dflags = CAM_DEBUG_NONE;
 			} else {
+				cam_dflags = start_ccb->cdbg.flags;
 				start_ccb->ccb_h.status = CAM_REQ_CMP;
 				xpt_print(cam_dpath, "debugging flags now %x\n",
 				    cam_dflags);
 			}
-		} else {
-			cam_dpath = NULL;
+		} else
 			start_ccb->ccb_h.status = CAM_REQ_CMP;
-		}
 		break;
 	}
 	case XPT_FREEZE_QUEUE:

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