git: 9781c28c6d63 - main - mpr(4): Fix unmatched devq release.

[Alexander Motin]

The branch main has been updated by mav:

URL: https://cgit.FreeBSD.org/src/commit/?id=9781c28c6d63cfa8438d1aa31f512a6b217a6b2b

commit 9781c28c6d63cfa8438d1aa31f512a6b217a6b2b
Author:     Alexander Motin <mav at FreeBSD.org>
AuthorDate: 2021-08-20 18:37:55 +0000
Commit:     Alexander Motin <mav at FreeBSD.org>
CommitDate: 2021-08-20 18:51:12 +0000

    mpr(4): Fix unmatched devq release.
    
    Before this change devq was frozen only if some command was sent to
    the target after reset started, but release was called always.  This
    change freezes the devq immediately, leaving mprsas_action_scsiio()
    check only to cover race condition due to different lock devq use.
    
    This should also avoid unnecessary requeue of the commands, creating
    additional log noise and confusing some broken apps.
    
    MFC after:      2 weeks
    Sponsored by:   iXsystems, Inc.
---
 sys/dev/mpr/mpr_sas.c | 29 +++++++++++++----------------
 1 file changed, 13 insertions(+), 16 deletions(-)

diff --git a/sys/dev/mpr/mpr_sas.c b/sys/dev/mpr/mpr_sas.c
index e1739028dd8f..a8bb7c90b5c4 100644
--- a/sys/dev/mpr/mpr_sas.c
+++ b/sys/dev/mpr/mpr_sas.c
@@ -237,7 +237,6 @@ mprsas_alloc_tm(struct mpr_softc *sc)
 void
 mprsas_free_tm(struct mpr_softc *sc, struct mpr_command *tm)
 {
-	int target_id = 0xFFFFFFFF;
 
 	MPR_FUNCTRACE(sc);
 	if (tm == NULL)
@@ -248,13 +247,10 @@ mprsas_free_tm(struct mpr_softc *sc, struct mpr_command *tm)
 	 * free the resources used for freezing the devq.  Must clear the
 	 * INRESET flag as well or scsi I/O will not work.
 	 */
-	if (tm->cm_targ != NULL) {
-		tm->cm_targ->flags &= ~MPRSAS_TARGET_INRESET;
-		target_id = tm->cm_targ->tid;
-	}
 	if (tm->cm_ccb) {
-		mpr_dprint(sc, MPR_INFO, "Unfreezing devq for target ID %d\n",
-		    target_id);
+		mpr_dprint(sc, MPR_XINFO, "Unfreezing devq for target ID %d\n",
+		    tm->cm_targ->tid);
+		tm->cm_targ->flags &= ~MPRSAS_TARGET_INRESET;
 		xpt_release_devq(tm->cm_ccb->ccb_h.path, 1, TRUE);
 		xpt_free_path(tm->cm_ccb->ccb_h.path);
 		xpt_free_ccb(tm->cm_ccb);
@@ -1923,13 +1919,11 @@ mprsas_action_scsiio(struct mprsas_softc *sassc, union ccb *ccb)
 	}
 
 	/*
-	 * If target has a reset in progress, freeze the devq and return.  The
-	 * devq will be released when the TM reset is finished.
+	 * If target has a reset in progress, the devq should be frozen.
+	 * Geting here we likely hit a race, so just requeue.
 	 */
 	if (targ->flags & MPRSAS_TARGET_INRESET) {
-		ccb->ccb_h.status = CAM_BUSY | CAM_DEV_QFRZN;
-		mpr_dprint(sc, MPR_INFO, "%s: Freezing devq for target ID %d\n",
-		    __func__, targ->tid);
+		ccb->ccb_h.status = CAM_REQUEUE_REQ | CAM_DEV_QFRZN;
 		xpt_freeze_devq(ccb->ccb_h.path, 1);
 		xpt_done(ccb);
 		return;
@@ -3426,10 +3420,9 @@ mprsas_async(void *callback_arg, uint32_t code, struct cam_path *path,
 }
 
 /*
- * Set the INRESET flag for this target so that no I/O will be sent to
- * the target until the reset has completed.  If an I/O request does
- * happen, the devq will be frozen.  The CCB holds the path which is
- * used to release the devq.  The devq is released and the CCB is freed
+ * Freeze the devq and set the INRESET flag so that no I/O will be sent to
+ * the target until the reset has completed.  The CCB holds the path which
+ * is used to release the devq.  The devq is released and the CCB is freed
  * when the TM completes.
  */
 void
@@ -3446,6 +3439,10 @@ mprsas_prepare_for_tm(struct mpr_softc *sc, struct mpr_command *tm,
 		    target->tid, lun_id) != CAM_REQ_CMP) {
 			xpt_free_ccb(ccb);
 		} else {
+			mpr_dprint(sc, MPR_XINFO,
+			    "%s: Freezing devq for target ID %d\n",
+			    __func__, target->tid);
+			xpt_freeze_devq(ccb->ccb_h.path, 1);
 			tm->cm_ccb = ccb;
 			tm->cm_targ = target;
 			target->flags |= MPRSAS_TARGET_INRESET;