[SCSI] ibmvfc: Improve ADISC timeout handling

The ibmvfc driver currently breaks the CRQ and essentially
resets the entire virtual FC adapter, killing all outstanding
ops to all attached targets, if an ADISC times out during target
discover/rediscovery. This patch adds some code to cancel the
ADISC if it times out, which prevents a single ADISC timeout from
affecting the other devices attached to the fabric.

Signed-off-by: Brian King <brking@linux.vnet.ibm.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

1 files changed, 97 insertions, 1 deletions

diff --git a/drivers/scsi/ibmvscsi/ibmvfc.c b/drivers/scsi/ibmvscsi/ibmvfc.c
index 0ac2dedb413..ea4abee7a2a 100644
--- a/drivers/scsi/ibmvscsi/ibmvfc.c
+++ b/drivers/scsi/ibmvscsi/ibmvfc.c
@@ -3123,6 +3123,7 @@ static void ibmvfc_tgt_adisc_done(struct ibmvfc_event *evt)
 
 	vhost->discovery_threads--;
 	ibmvfc_set_tgt_action(tgt, IBMVFC_TGT_ACTION_NONE);
+	del_timer(&tgt->timer);
 
 	switch (status) {
 	case IBMVFC_MAD_SUCCESS:
@@ -3179,9 +3180,89 @@ static void ibmvfc_init_passthru(struct ibmvfc_event *evt)
 }
 
 /**
+ * ibmvfc_tgt_adisc_cancel_done - Completion handler when cancelling an ADISC
+ * @evt:		ibmvfc event struct
+ *
+ * Just cleanup this event struct. Everything else is handled by
+ * the ADISC completion handler. If the ADISC never actually comes
+ * back, we still have the timer running on the ADISC event struct
+ * which will fire and cause the CRQ to get reset.
+ *
+ **/
+static void ibmvfc_tgt_adisc_cancel_done(struct ibmvfc_event *evt)
+{
+	struct ibmvfc_host *vhost = evt->vhost;
+	struct ibmvfc_target *tgt = evt->tgt;
+
+	tgt_dbg(tgt, "ADISC cancel complete\n");
+	vhost->abort_threads--;
+	ibmvfc_free_event(evt);
+	kref_put(&tgt->kref, ibmvfc_release_tgt);
+	wake_up(&vhost->work_wait_q);
+}
+
+/**
+ * ibmvfc_adisc_timeout - Handle an ADISC timeout
+ * @tgt:		ibmvfc target struct
+ *
+ * If an ADISC times out, send a cancel. If the cancel times
+ * out, reset the CRQ. When the ADISC comes back as cancelled,
+ * log back into the target.
+ **/
+static void ibmvfc_adisc_timeout(struct ibmvfc_target *tgt)
+{
+	struct ibmvfc_host *vhost = tgt->vhost;
+	struct ibmvfc_event *evt;
+	struct ibmvfc_tmf *tmf;
+	unsigned long flags;
+	int rc;
+
+	tgt_dbg(tgt, "ADISC timeout\n");
+	spin_lock_irqsave(vhost->host->host_lock, flags);
+	if (vhost->abort_threads >= disc_threads ||
+	    tgt->action != IBMVFC_TGT_ACTION_INIT_WAIT ||
+	    vhost->state != IBMVFC_INITIALIZING ||
+	    vhost->action != IBMVFC_HOST_ACTION_QUERY_TGTS) {
+		spin_unlock_irqrestore(vhost->host->host_lock, flags);
+		return;
+	}
+
+	vhost->abort_threads++;
+	kref_get(&tgt->kref);
+	evt = ibmvfc_get_event(vhost);
+	ibmvfc_init_event(evt, ibmvfc_tgt_adisc_cancel_done, IBMVFC_MAD_FORMAT);
+
+	evt->tgt = tgt;
+	tmf = &evt->iu.tmf;
+	memset(tmf, 0, sizeof(*tmf));
+	tmf->common.version = 1;
+	tmf->common.opcode = IBMVFC_TMF_MAD;
+	tmf->common.length = sizeof(*tmf);
+	tmf->scsi_id = tgt->scsi_id;
+	tmf->cancel_key = tgt->cancel_key;
+
+	rc = ibmvfc_send_event(evt, vhost, default_timeout);
+
+	if (rc) {
+		tgt_err(tgt, "Failed to send cancel event for ADISC. rc=%d\n", rc);
+		vhost->abort_threads--;
+		kref_put(&tgt->kref, ibmvfc_release_tgt);
+		__ibmvfc_reset_host(vhost);
+	} else
+		tgt_dbg(tgt, "Attempting to cancel ADISC\n");
+	spin_unlock_irqrestore(vhost->host->host_lock, flags);
+}
+
+/**
  * ibmvfc_tgt_adisc - Initiate an ADISC for specified target
  * @tgt:		ibmvfc target struct
  *
+ * When sending an ADISC we end up with two timers running. The
+ * first timer is the timer in the ibmvfc target struct. If this
+ * fires, we send a cancel to the target. The second timer is the
+ * timer on the ibmvfc event for the ADISC, which is longer. If that
+ * fires, it means the ADISC timed out and our attempt to cancel it
+ * also failed, so we need to reset the CRQ.
  **/
 static void ibmvfc_tgt_adisc(struct ibmvfc_target *tgt)
 {
@@ -3202,6 +3283,7 @@ static void ibmvfc_tgt_adisc(struct ibmvfc_target *tgt)
 	mad = &evt->iu.passthru;
 	mad->iu.flags = IBMVFC_FC_ELS;
 	mad->iu.scsi_id = tgt->scsi_id;
+	mad->iu.cancel_key = tgt->cancel_key;
 
 	mad->fc_iu.payload[0] = IBMVFC_ADISC;
 	memcpy(&mad->fc_iu.payload[2], &vhost->login_buf->resp.port_name,
@@ -3210,9 +3292,19 @@ static void ibmvfc_tgt_adisc(struct ibmvfc_target *tgt)
 	       sizeof(vhost->login_buf->resp.node_name));
 	mad->fc_iu.payload[6] = vhost->login_buf->resp.scsi_id & 0x00ffffff;
 
+	if (timer_pending(&tgt->timer))
+		mod_timer(&tgt->timer, jiffies + (IBMVFC_ADISC_TIMEOUT * HZ));
+	else {
+		tgt->timer.data = (unsigned long) tgt;
+		tgt->timer.expires = jiffies + (IBMVFC_ADISC_TIMEOUT * HZ);
+		tgt->timer.function = (void (*)(unsigned long))ibmvfc_adisc_timeout;
+		add_timer(&tgt->timer);
+	}
+
 	ibmvfc_set_tgt_action(tgt, IBMVFC_TGT_ACTION_INIT_WAIT);
-	if (ibmvfc_send_event(evt, vhost, default_timeout)) {
+	if (ibmvfc_send_event(evt, vhost, IBMVFC_ADISC_PLUS_CANCEL_TIMEOUT)) {
 		vhost->discovery_threads--;
+		del_timer(&tgt->timer);
 		ibmvfc_set_tgt_action(tgt, IBMVFC_TGT_ACTION_NONE);
 		kref_put(&tgt->kref, ibmvfc_release_tgt);
 	} else
@@ -3340,6 +3432,8 @@ static int ibmvfc_alloc_target(struct ibmvfc_host *vhost, u64 scsi_id)
 	tgt->new_scsi_id = scsi_id;
 	tgt->vhost = vhost;
 	tgt->need_login = 1;
+	tgt->cancel_key = vhost->task_set++;
+	init_timer(&tgt->timer);
 	kref_init(&tgt->kref);
 	ibmvfc_init_tgt(tgt, ibmvfc_tgt_implicit_logout);
 	spin_lock_irqsave(vhost->host->host_lock, flags);
@@ -3734,6 +3828,7 @@ static void ibmvfc_do_work(struct ibmvfc_host *vhost)
 				spin_unlock_irqrestore(vhost->host->host_lock, flags);
 				if (rport)
 					fc_remote_port_delete(rport);
+				del_timer_sync(&tgt->timer);
 				kref_put(&tgt->kref, ibmvfc_release_tgt);
 				return;
 			}
@@ -4061,6 +4156,7 @@ static int ibmvfc_probe(struct vio_dev *vdev, const struct vio_device_id *id)
 	vhost->dev = dev;
 	vhost->partition_number = -1;
 	vhost->log_level = log_level;
+	vhost->task_set = 1;
 	strcpy(vhost->partition_name, "UNKNOWN");
 	init_waitqueue_head(&vhost->work_wait_q);
 	init_waitqueue_head(&vhost->init_wait_q);