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Date:      Sat, 14 Nov 2009 20:23:20 +0000 (UTC)
From:      Alexander Motin <mav@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org
Subject:   svn commit: r199280 - head/sys/cam
Message-ID:  <200911142023.nAEKNKDl012439@svn.freebsd.org>
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Author: mav
Date: Sat Nov 14 20:23:20 2009
New Revision: 199280
URL: http://svn.freebsd.org/changeset/base/199280

Log:
  MFp4:
  Remove code that years ago was closing race between request submission
  to SIM and device/SIM freeze. That race become impossible after moving from
  spl to mutex locking, while this workaround causes some unexpected effects.

Modified:
  head/sys/cam/cam_xpt.c

Modified: head/sys/cam/cam_xpt.c
==============================================================================
--- head/sys/cam/cam_xpt.c	Sat Nov 14 20:13:38 2009	(r199279)
+++ head/sys/cam/cam_xpt.c	Sat Nov 14 20:23:20 2009	(r199280)
@@ -3273,16 +3273,13 @@ xpt_run_dev_sendq(struct cam_eb *bus)
 
 	devq->send_queue.qfrozen_cnt++;
 	while ((devq->send_queue.entries > 0)
-	    && (devq->send_openings > 0)) {
+	    && (devq->send_openings > 0)
+	    && (devq->send_queue.qfrozen_cnt <= 1)) {
 		struct	cam_ed_qinfo *qinfo;
 		struct	cam_ed *device;
 		union ccb *work_ccb;
 		struct	cam_sim *sim;
 
-	    	if (devq->send_queue.qfrozen_cnt > 1) {
-			break;
-		}
-
 		qinfo = (struct cam_ed_qinfo *)camq_remove(&devq->send_queue,
 							   CAMQ_HEAD);
 		device = qinfo->device;
@@ -3330,9 +3327,7 @@ xpt_run_dev_sendq(struct cam_eb *bus)
 			}
 			mtx_unlock(&xsoftc.xpt_lock);
 		}
-		devq->active_dev = device;
 		cam_ccbq_remove_ccb(&device->ccbq, work_ccb);
-
 		cam_ccbq_send_ccb(&device->ccbq, work_ccb);
 
 		devq->send_openings--;
@@ -3370,8 +3365,6 @@ xpt_run_dev_sendq(struct cam_eb *bus)
 		 */
 		sim = work_ccb->ccb_h.path->bus->sim;
 		(*(sim->sim_action))(sim, work_ccb);
-
-		devq->active_dev = NULL;
 	}
 	devq->send_queue.qfrozen_cnt--;
 }
@@ -4102,45 +4095,18 @@ xpt_dev_async_default(u_int32_t async_co
 u_int32_t
 xpt_freeze_devq(struct cam_path *path, u_int count)
 {
-	struct ccb_hdr *ccbh;
 
 	mtx_assert(path->bus->sim->mtx, MA_OWNED);
-
 	path->device->ccbq.queue.qfrozen_cnt += count;
-
-	/*
-	 * Mark the last CCB in the queue as needing
-	 * to be requeued if the driver hasn't
-	 * changed it's state yet.  This fixes a race
-	 * where a ccb is just about to be queued to
-	 * a controller driver when it's interrupt routine
-	 * freezes the queue.  To completly close the
-	 * hole, controller drives must check to see
-	 * if a ccb's status is still CAM_REQ_INPROG
-	 * just before they queue
-	 * the CCB.  See ahc_action/ahc_freeze_devq for
-	 * an example.
-	 */
-	ccbh = TAILQ_LAST(&path->device->ccbq.active_ccbs, ccb_hdr_tailq);
-	if (ccbh && ccbh->status == CAM_REQ_INPROG)
-		ccbh->status = CAM_REQUEUE_REQ;
 	return (path->device->ccbq.queue.qfrozen_cnt);
 }
 
 u_int32_t
 xpt_freeze_simq(struct cam_sim *sim, u_int count)
 {
-	mtx_assert(sim->mtx, MA_OWNED);
 
+	mtx_assert(sim->mtx, MA_OWNED);
 	sim->devq->send_queue.qfrozen_cnt += count;
-	if (sim->devq->active_dev != NULL) {
-		struct ccb_hdr *ccbh;
-
-		ccbh = TAILQ_LAST(&sim->devq->active_dev->ccbq.active_ccbs,
-				  ccb_hdr_tailq);
-		if (ccbh && ccbh->status == CAM_REQ_INPROG)
-			ccbh->status = CAM_REQUEUE_REQ;
-	}
 	return (sim->devq->send_queue.qfrozen_cnt);
 }

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