Make cam_periph_runccb be safe to call when we can only do polling.

Sponsored by: Netflix
Differential Revision: https://reviews.freebsd.org/D13388

sys/cam/cam_periph.c

@@ -1160,7 +1160,11 @@ cam_periph_runccb(union ccb *ccb,
 	struct bintime *starttime;
 	struct bintime ltime;
 	int error;
- 
+	bool sched_stopped;
+	struct mtx *periph_mtx;
+	struct cam_periph *periph;
+	uint32_t timeout = 1;
+
 	starttime = NULL;
 	xpt_path_assert(ccb->ccb_h.path, MA_OWNED);
 	KASSERT((ccb->ccb_h.flags & CAM_UNLOCKED) == 0,
@@ -1180,21 +1184,47 @@ cam_periph_runccb(union ccb *ccb,
 		devstat_start_transaction(ds, starttime);
 	}
 
+	sched_stopped = SCHEDULER_STOPPED();
 	ccb->ccb_h.cbfcnp = cam_periph_done;
-	xpt_action(ccb);
+	periph = xpt_path_periph(ccb->ccb_h.path);
- 
+	periph_mtx = cam_periph_mtx(periph);
-	do {
+
-		cam_periph_ccbwait(ccb);
+	/*
-		if ((ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP)
+	 * If we're polling, then we need to ensure that we have ample resources
-			error = 0;
+	 * in the periph. We also need to drop the periph lock while we're polling.
-		else if (error_routine != NULL) {
+	 * cam_periph_error can reschedule the ccb by calling xpt_action and returning
-			ccb->ccb_h.cbfcnp = cam_periph_done;
+	 * ERESTART, so we have to effect the polling in the do loop below.
-			error = (*error_routine)(ccb, camflags, sense_flags);
+	 */
-		} else
+	if (sched_stopped) {
-			error = 0;
+		mtx_unlock(periph_mtx);
+		timeout = xpt_poll_setup(ccb);
+	}
+
+	if (timeout == 0) {
+		ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
+		error = EBUSY;
+	} else {
+		xpt_action(ccb);
+		do {
+			if (!sched_stopped)
+				cam_periph_ccbwait(ccb);
+			else {
+				xpt_pollwait(ccb, timeout);
+				timeout = ccb->ccb_h.timeout * 10;
+			}
+			if ((ccb->ccb_h.status & CAM_STATUS_MASK) == CAM_REQ_CMP)
+				error = 0;
+			else if (error_routine != NULL) {
+				ccb->ccb_h.cbfcnp = cam_periph_done;
+				error = (*error_routine)(ccb, camflags, sense_flags);
+			} else
+				error = 0;
+		} while (error == ERESTART);
+	}
+
+	if (sched_stopped)
+		mtx_lock(periph_mtx);
 
-	} while (error == ERESTART);
-          
 	if ((ccb->ccb_h.status & CAM_DEV_QFRZN) != 0) {
 		cam_release_devq(ccb->ccb_h.path,
 				 /* relsim_flags */0,

sys/cam/cam_xpt.c

@@ -3204,8 +3204,8 @@ call_sim:
 		start_ccb->ccb_h.status));
 }
 
-void
+uint32_t
-xpt_polled_action(union ccb *start_ccb)
+xpt_poll_setup(union ccb *start_ccb)
 {
 	u_int32_t timeout;
 	struct	  cam_sim *sim;
@@ -3219,8 +3219,6 @@ xpt_polled_action(union ccb *start_ccb)
 	mtx = sim->mtx;
 	dev = start_ccb->ccb_h.path->device;
 
-	mtx_unlock(&dev->device_mtx);
-
 	/*
 	 * Steal an opening so that no other queued requests
 	 * can get it before us while we simulate interrupts.
@@ -3242,29 +3240,57 @@ xpt_polled_action(union ccb *start_ccb)
 	dev->ccbq.dev_openings++;
 	mtx_unlock(&devq->send_mtx);
 
-	if (timeout != 0) {
+	return (timeout);
+}
+
+void
+xpt_pollwait(union ccb *start_ccb, uint32_t timeout)
+{
+	struct cam_sim	*sim;
+	struct mtx	*mtx;
+
+	sim = start_ccb->ccb_h.path->bus->sim;
+	mtx = sim->mtx;
+
+	while (--timeout > 0) {
+		if (mtx)
+			mtx_lock(mtx);
+		(*(sim->sim_poll))(sim);
+		if (mtx)
+			mtx_unlock(mtx);
+		camisr_runqueue();
+		if ((start_ccb->ccb_h.status & CAM_STATUS_MASK)
+		    != CAM_REQ_INPROG)
+			break;
+		DELAY(100);
+	}
+
+	if (timeout == 0) {
+		/*
+		 * XXX Is it worth adding a sim_timeout entry
+		 * point so we can attempt recovery?  If
+		 * this is only used for dumps, I don't think
+		 * it is.
+		 */
+		start_ccb->ccb_h.status = CAM_CMD_TIMEOUT;
+	}
+}
+
+void
+xpt_polled_action(union ccb *start_ccb)
+{
+	uint32_t	timeout;
+	struct cam_ed	*dev;
+
+	timeout = start_ccb->ccb_h.timeout * 10;
+	dev = start_ccb->ccb_h.path->device;
+
+	mtx_unlock(&dev->device_mtx);
+
+	timeout = xpt_poll_setup(start_ccb);
+	if (timeout > 0) {
 		xpt_action(start_ccb);
-		while(--timeout > 0) {
+		xpt_pollwait(start_ccb, timeout);
-			if (mtx)
-				mtx_lock(mtx);
-			(*(sim->sim_poll))(sim);
-			if (mtx)
-				mtx_unlock(mtx);
-			camisr_runqueue();
-			if ((start_ccb->ccb_h.status  & CAM_STATUS_MASK)
-			    != CAM_REQ_INPROG)
-				break;
-			DELAY(100);
-		}
-		if (timeout == 0) {
-			/*
-			 * XXX Is it worth adding a sim_timeout entry
-			 * point so we can attempt recovery?  If
-			 * this is only used for dumps, I don't think
-			 * it is.
-			 */
-			start_ccb->ccb_h.status = CAM_CMD_TIMEOUT;
-		}
 	} else {
 		start_ccb->ccb_h.status = CAM_RESRC_UNAVAIL;
 	}
@@ -3306,6 +3332,7 @@ xpt_schedule_dev(struct camq *queue, cam_pinfo *pinfo,
 
 	CAM_DEBUG_PRINT(CAM_DEBUG_XPT, ("xpt_schedule_dev\n"));
 
+
 	old_priority = pinfo->priority;
 
 	/*

sys/cam/cam_xpt.h

@@ -144,6 +144,8 @@ void			xpt_copy_path(struct cam_path *new_path,
 void			xpt_release_path(struct cam_path *path);
 
 const char *		xpt_action_name(uint32_t action);
+void			xpt_pollwait(union ccb *start_ccb, uint32_t timeout);
+uint32_t		xpt_poll_setup(union ccb *start_ccb);
 
 #endif /* _KERNEL */