scsi: scsi_transport_srp: Sanitize scsi_target_block/unblock sequences

The SCSI midlayer does not allow state transitions from SDEV_BLOCK to
SDEV_BLOCK so calling scsi_target_block() from __rport_fast_io_fail() is
wrong as the port is already blocked.  Similarly, we don't need to call
scsi_target_unblock() afterwards as the function has already done this.

Link: https://lore.kernel.org/r/20200728134833.42547-1-hare@suse.de
Reviewed-by: Bart Van Assche <bvanassche@acm.org>
Reviewed-by: Laurence Oberman <loberman@redhat.com>
Signed-off-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>

diff --git a/drivers/scsi/scsi_transport_srp.c b/drivers/scsi/scsi_transport_srp.c
index d4d1104..cba1cf6 100644 (file)
--- a/drivers/scsi/scsi_transport_srp.c
+++ b/drivers/scsi/scsi_transport_srp.c
@@ -395,6 +395,10 @@ static void srp_reconnect_work(struct work_struct *work)
        }
 }
 
+/*
+ * scsi_target_block() must have been called before this function is
+ * called to guarantee that no .queuecommand() calls are in progress.
+ */
 static void __rport_fail_io_fast(struct srp_rport *rport)
 {
        struct Scsi_Host *shost = rport_to_shost(rport);
@@ -404,11 +408,7 @@ static void __rport_fail_io_fast(struct srp_rport *rport)
 
        if (srp_rport_set_state(rport, SRP_RPORT_FAIL_FAST))
                return;
-       /*
-        * Call scsi_target_block() to wait for ongoing shost->queuecommand()
-        * calls before invoking i->f->terminate_rport_io().
-        */
-       scsi_target_block(rport->dev.parent);
+
        scsi_target_unblock(rport->dev.parent, SDEV_TRANSPORT_OFFLINE);
 
        /* Involve the LLD if possible to terminate all I/O on the rport. */
@@ -570,8 +570,6 @@ int srp_reconnect_rport(struct srp_rport *rport)
                 * failure timers if these had not yet been started.
                 */
                __rport_fail_io_fast(rport);
-               scsi_target_unblock(&shost->shost_gendev,
-                                   SDEV_TRANSPORT_OFFLINE);
                __srp_start_tl_fail_timers(rport);
        } else if (rport->state != SRP_RPORT_BLOCKED) {
                scsi_target_unblock(&shost->shost_gendev,