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Date:      Tue, 4 Apr 2017 17:59:10 +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-11@freebsd.org
Subject:   svn commit: r316498 - in stable/11/sys: cam sys
Message-ID:  <201704041759.v34HxAKh000514@repo.freebsd.org>

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Author: mav
Date: Tue Apr  4 17:59:10 2017
New Revision: 316498
URL: https://svnweb.freebsd.org/changeset/base/316498

Log:
  MFC r315673, r315674: Make CAM SIM lock optional.
  
  For three years now CAM does not use SIM lock, but still enforces SIM to
  use it.  Remove this requirement, allowing SIMs to have any locking they
  prefer, if they pass no mutex to cam_sim_alloc().

Modified:
  stable/11/sys/cam/cam_sim.c
  stable/11/sys/cam/cam_xpt.c
  stable/11/sys/sys/param.h
Directory Properties:
  stable/11/   (props changed)

Modified: stable/11/sys/cam/cam_sim.c
==============================================================================
--- stable/11/sys/cam/cam_sim.c	Tue Apr  4 17:32:08 2017	(r316497)
+++ stable/11/sys/cam/cam_sim.c	Tue Apr  4 17:59:10 2017	(r316498)
@@ -46,6 +46,9 @@ __FBSDID("$FreeBSD$");
 
 static MALLOC_DEFINE(M_CAMSIM, "CAM SIM", "CAM SIM buffers");
 
+static struct mtx cam_sim_free_mtx;
+MTX_SYSINIT(cam_sim_free_init, &cam_sim_free_mtx, "CAM SIM free lock", MTX_DEF);
+
 struct cam_devq *
 cam_simq_alloc(u_int32_t max_sim_transactions)
 {
@@ -66,9 +69,6 @@ cam_sim_alloc(sim_action_func sim_action
 {
 	struct cam_sim *sim;
 
-	if (mtx == NULL)
-		return (NULL);
-
 	sim = (struct cam_sim *)malloc(sizeof(struct cam_sim),
 	    M_CAMSIM, M_ZERO | M_NOWAIT);
 
@@ -101,16 +101,23 @@ cam_sim_alloc(sim_action_func sim_action
 void
 cam_sim_free(struct cam_sim *sim, int free_devq)
 {
+	struct mtx *mtx = sim->mtx;
 	int error;
 
-	mtx_assert(sim->mtx, MA_OWNED);
+	if (mtx) {
+		mtx_assert(mtx, MA_OWNED);
+	} else {
+		mtx = &cam_sim_free_mtx;
+		mtx_lock(mtx);
+	}
 	sim->refcount--;
 	if (sim->refcount > 0) {
-		error = msleep(sim, sim->mtx, PRIBIO, "simfree", 0);
+		error = msleep(sim, mtx, PRIBIO, "simfree", 0);
 		KASSERT(error == 0, ("invalid error value for msleep(9)"));
 	}
-
 	KASSERT(sim->refcount == 0, ("sim->refcount == 0"));
+	if (sim->mtx == NULL)
+		mtx_unlock(mtx);
 
 	if (free_devq)
 		cam_simq_free(sim->devq);
@@ -120,31 +127,43 @@ cam_sim_free(struct cam_sim *sim, int fr
 void
 cam_sim_release(struct cam_sim *sim)
 {
-	int lock;
+	struct mtx *mtx = sim->mtx;
 
-	lock = (mtx_owned(sim->mtx) == 0);
-	if (lock)
-		CAM_SIM_LOCK(sim);
+	if (mtx) {
+		if (!mtx_owned(mtx))
+			mtx_lock(mtx);
+		else
+			mtx = NULL;
+	} else {
+		mtx = &cam_sim_free_mtx;
+		mtx_lock(mtx);
+	}
 	KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
 	sim->refcount--;
 	if (sim->refcount == 0)
 		wakeup(sim);
-	if (lock)
-		CAM_SIM_UNLOCK(sim);
+	if (mtx)
+		mtx_unlock(mtx);
 }
 
 void
 cam_sim_hold(struct cam_sim *sim)
 {
-	int lock;
+	struct mtx *mtx = sim->mtx;
 
-	lock = (mtx_owned(sim->mtx) == 0);
-	if (lock)
-		CAM_SIM_LOCK(sim);
+	if (mtx) {
+		if (!mtx_owned(mtx))
+			mtx_lock(mtx);
+		else
+			mtx = NULL;
+	} else {
+		mtx = &cam_sim_free_mtx;
+		mtx_lock(mtx);
+	}
 	KASSERT(sim->refcount >= 1, ("sim->refcount >= 1"));
 	sim->refcount++;
-	if (lock)
-		CAM_SIM_UNLOCK(sim);
+	if (mtx)
+		mtx_unlock(mtx);
 }
 
 void

Modified: stable/11/sys/cam/cam_xpt.c
==============================================================================
--- stable/11/sys/cam/cam_xpt.c	Tue Apr  4 17:32:08 2017	(r316497)
+++ stable/11/sys/cam/cam_xpt.c	Tue Apr  4 17:59:10 2017	(r316498)
@@ -2486,7 +2486,7 @@ xpt_action_default(union ccb *start_ccb)
 {
 	struct cam_path *path;
 	struct cam_sim *sim;
-	int lock;
+	struct mtx *mtx;
 
 	path = start_ccb->ccb_h.path;
 	CAM_DEBUG(path, CAM_DEBUG_TRACE,
@@ -2647,16 +2647,18 @@ xpt_action_default(union ccb *start_ccb)
 	case XPT_PATH_INQ:
 call_sim:
 		sim = path->bus->sim;
-		lock = (mtx_owned(sim->mtx) == 0);
-		if (lock)
-			CAM_SIM_LOCK(sim);
+		mtx = sim->mtx;
+		if (mtx && !mtx_owned(mtx))
+			mtx_lock(mtx);
+		else
+			mtx = NULL;
 		CAM_DEBUG(path, CAM_DEBUG_TRACE,
 		    ("sim->sim_action: func=%#x\n", start_ccb->ccb_h.func_code));
 		(*(sim->sim_action))(sim, start_ccb);
 		CAM_DEBUG(path, CAM_DEBUG_TRACE,
 		    ("sim->sim_action: status=%#x\n", start_ccb->ccb_h.status));
-		if (lock)
-			CAM_SIM_UNLOCK(sim);
+		if (mtx)
+			mtx_unlock(mtx);
 		break;
 	case XPT_PATH_STATS:
 		start_ccb->cpis.last_reset = path->bus->last_reset;
@@ -2878,8 +2880,8 @@ call_sim:
 				break;
 			}
 			cur_entry->event_enable = csa->event_enable;
-			cur_entry->event_lock =
-			    mtx_owned(path->bus->sim->mtx) ? 1 : 0;
+			cur_entry->event_lock = (path->bus->sim->mtx &&
+			    mtx_owned(path->bus->sim->mtx)) ? 1 : 0;
 			cur_entry->callback_arg = csa->callback_arg;
 			cur_entry->callback = csa->callback;
 			SLIST_INSERT_HEAD(async_head, cur_entry, links);
@@ -3044,10 +3046,12 @@ xpt_polled_action(union ccb *start_ccb)
 	struct	  cam_sim *sim;
 	struct	  cam_devq *devq;
 	struct	  cam_ed *dev;
+	struct mtx *mtx;
 
 	timeout = start_ccb->ccb_h.timeout * 10;
 	sim = start_ccb->ccb_h.path->bus->sim;
 	devq = sim->devq;
+	mtx = sim->mtx;
 	dev = start_ccb->ccb_h.path->device;
 
 	mtx_unlock(&dev->device_mtx);
@@ -3062,9 +3066,11 @@ xpt_polled_action(union ccb *start_ccb)
 	    (--timeout > 0)) {
 		mtx_unlock(&devq->send_mtx);
 		DELAY(100);
-		CAM_SIM_LOCK(sim);
+		if (mtx)
+			mtx_lock(mtx);
 		(*(sim->sim_poll))(sim);
-		CAM_SIM_UNLOCK(sim);
+		if (mtx)
+			mtx_unlock(mtx);
 		camisr_runqueue();
 		mtx_lock(&devq->send_mtx);
 	}
@@ -3074,9 +3080,11 @@ xpt_polled_action(union ccb *start_ccb)
 	if (timeout != 0) {
 		xpt_action(start_ccb);
 		while(--timeout > 0) {
-			CAM_SIM_LOCK(sim);
+			if (mtx)
+				mtx_lock(mtx);
 			(*(sim->sim_poll))(sim);
-			CAM_SIM_UNLOCK(sim);
+			if (mtx)
+				mtx_unlock(mtx);
 			camisr_runqueue();
 			if ((start_ccb->ccb_h.status  & CAM_STATUS_MASK)
 			    != CAM_REQ_INPROG)
@@ -3234,7 +3242,7 @@ static void
 xpt_run_devq(struct cam_devq *devq)
 {
 	char cdb_str[(SCSI_MAX_CDBLEN * 3) + 1];
-	int lock;
+	struct mtx *mtx;
 
 	CAM_DEBUG_PRINT(CAM_DEBUG_XPT, ("xpt_run_devq\n"));
 
@@ -3336,13 +3344,15 @@ xpt_run_devq(struct cam_devq *devq)
 		 * queued device, rather than the one from the calling bus.
 		 */
 		sim = device->sim;
-		lock = (mtx_owned(sim->mtx) == 0);
-		if (lock)
-			CAM_SIM_LOCK(sim);
+		mtx = sim->mtx;
+		if (mtx && !mtx_owned(mtx))
+			mtx_lock(mtx);
+		else
+			mtx = NULL;
 		work_ccb->ccb_h.qos.sim_data = sbinuptime(); // xxx uintprt_t too small 32bit platforms
 		(*(sim->sim_action))(sim, work_ccb);
-		if (lock)
-			CAM_SIM_UNLOCK(sim);
+		if (mtx)
+			mtx_unlock(mtx);
 		mtx_lock(&devq->send_mtx);
 	}
 	devq->send_queue.qfrozen_cnt--;
@@ -3848,8 +3858,6 @@ xpt_bus_register(struct cam_sim *sim, de
 	struct cam_path *path;
 	cam_status status;
 
-	mtx_assert(sim->mtx, MA_OWNED);
-
 	sim->bus_id = bus;
 	new_bus = (struct cam_eb *)malloc(sizeof(*new_bus),
 					  M_CAMXPT, M_NOWAIT|M_ZERO);
@@ -4206,7 +4214,7 @@ xpt_async_bcast(struct async_list *async
 		struct cam_path *path, void *async_arg)
 {
 	struct async_node *cur_entry;
-	int lock;
+	struct mtx *mtx;
 
 	cur_entry = SLIST_FIRST(async_head);
 	while (cur_entry != NULL) {
@@ -4218,14 +4226,15 @@ xpt_async_bcast(struct async_list *async
 		 */
 		next_entry = SLIST_NEXT(cur_entry, links);
 		if ((cur_entry->event_enable & async_code) != 0) {
-			lock = cur_entry->event_lock;
-			if (lock)
-				CAM_SIM_LOCK(path->device->sim);
+			mtx = cur_entry->event_lock ?
+			    path->device->sim->mtx : NULL;
+			if (mtx)
+				mtx_lock(mtx);
 			cur_entry->callback(cur_entry->callback_arg,
 					    async_code, path,
 					    async_arg);
-			if (lock)
-				CAM_SIM_UNLOCK(path->device->sim);
+			if (mtx)
+				mtx_unlock(mtx);
 		}
 		cur_entry = next_entry;
 	}

Modified: stable/11/sys/sys/param.h
==============================================================================
--- stable/11/sys/sys/param.h	Tue Apr  4 17:32:08 2017	(r316497)
+++ stable/11/sys/sys/param.h	Tue Apr  4 17:59:10 2017	(r316498)
@@ -58,7 +58,7 @@
  *		in the range 5 to 9.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 1100511	/* Master, propagated to newvers */
+#define __FreeBSD_version 1100512	/* Master, propagated to newvers */
 
 /*
  * __FreeBSD_kernel__ indicates that this system uses the kernel of FreeBSD,



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