[SCSI] aic79xx: check for non-NULL scb in ahd_handle_nonpkt_busfree

When removing several devices aic79xx will occasionally Oops
in ahd_handle_nonpkt_busfree during rescan. Looking at the
code I found that we're indeed not checking if the scb in
question is NULL. So check for it before accessing it.

Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>

1 files changed, 31 insertions, 22 deletions

diff --git a/drivers/scsi/aic7xxx/aic79xx_core.c b/drivers/scsi/aic7xxx/aic79xx_core.c
index 4d419c155ce9..78971db5b60e 100644
--- a/drivers/scsi/aic7xxx/aic79xx_core.c
+++ b/drivers/scsi/aic7xxx/aic79xx_core.c
@@ -3171,13 +3171,16 @@ ahd_handle_nonpkt_busfree(struct ahd_softc *ahd)
                                 tinfo->curr.transport_version = 2;
                                 tinfo->goal.transport_version = 2;
                                 tinfo->goal.ppr_options = 0;
-                                /*
-                                 * Remove any SCBs in the waiting for selection
-                                 * queue that may also be for this target so
-                                 * that command ordering is preserved.
-                                 */
-                                ahd_freeze_devq(ahd, scb);
-                                ahd_qinfifo_requeue_tail(ahd, scb);
+                                if (scb != NULL) {
+                                        /*
+                                         * Remove any SCBs in the waiting
+                                         * for selection queue that may
+                                         * also be for this target so that
+                                         * command ordering is preserved.
+                                         */
+                                        ahd_freeze_devq(ahd, scb);
+                                        ahd_qinfifo_requeue_tail(ahd, scb);
+                                }
                                 printerror = 0;
                         }
                 } else if (ahd_sent_msg(ahd, AHDMSG_EXT, MSG_EXT_WDTR, FALSE)
@@ -3194,13 +3197,16 @@ ahd_handle_nonpkt_busfree(struct ahd_softc *ahd)
                                       MSG_EXT_WDTR_BUS_8_BIT,
                                       AHD_TRANS_CUR|AHD_TRANS_GOAL,
                                       /*paused*/TRUE);
-                        /*
-                         * Remove any SCBs in the waiting for selection
-                         * queue that may also be for this target so that
-                         * command ordering is preserved.
-                         */
-                        ahd_freeze_devq(ahd, scb);
-                        ahd_qinfifo_requeue_tail(ahd, scb);
+                        if (scb != NULL) {
+                                /*
+                                 * Remove any SCBs in the waiting for
+                                 * selection queue that may also be for
+                                 * this target so that command ordering
+                                 * is preserved.
+                                 */
+                                ahd_freeze_devq(ahd, scb);
+                                ahd_qinfifo_requeue_tail(ahd, scb);
+                        }
                         printerror = 0;
                 } else if (ahd_sent_msg(ahd, AHDMSG_EXT, MSG_EXT_SDTR, FALSE)
                         && ppr_busfree == 0) {
@@ -3217,13 +3223,16 @@ ahd_handle_nonpkt_busfree(struct ahd_softc *ahd)
                                         /*ppr_options*/0,
                                         AHD_TRANS_CUR|AHD_TRANS_GOAL,
                                         /*paused*/TRUE);
-                        /*
-                         * Remove any SCBs in the waiting for selection
-                         * queue that may also be for this target so that
-                         * command ordering is preserved.
-                         */
-                        ahd_freeze_devq(ahd, scb);
-                        ahd_qinfifo_requeue_tail(ahd, scb);
+                        if (scb != NULL) {
+                                /*
+                                 * Remove any SCBs in the waiting for
+                                 * selection queue that may also be for
+                                 * this target so that command ordering
+                                 * is preserved.
+                                 */
+                                ahd_freeze_devq(ahd, scb);
+                                ahd_qinfifo_requeue_tail(ahd, scb);
+                        }
                         printerror = 0;
                 } else if ((ahd->msg_flags & MSG_FLAG_EXPECT_IDE_BUSFREE) != 0
                         && ahd_sent_msg(ahd, AHDMSG_1B,
@@ -3251,7 +3260,7 @@ ahd_handle_nonpkt_busfree(struct ahd_softc *ahd)
          * the message phases.  We check it last in case we
          * had to send some other message that caused a busfree.
          */
-        if (printerror != 0
+        if (scb != NULL && printerror != 0
          && (lastphase == P_MESGIN || lastphase == P_MESGOUT)
          && ((ahd->msg_flags & MSG_FLAG_EXPECT_PPR_BUSFREE) != 0)) {