[SCSI] libfc: fix fc_eh_host_reset

Current fc_eh_host_reset leaves lport offline
permanently  due to FLOGI response getting
handled by LOGO response from last reset as both
had same exchange id.

So fix this by having end to end exches clean-up
using exchange abort along exches reset
done from fc_eh_host_reset. This would avoid
exchanges collision between the sessions across
the reset. In this case implicit login should have
done that but no aborting support for FIP
frames, so just wait till lport->r_a_tov before
restarting next flogi to ensure all exchanges
are good to use again for next session.

Below is the trace of LOGO from older session
coming ahead of FLOGI response with same exche id
0x203:-

617  86.435165     4e.00.0b -> ff.ff.fc     FC ELS LOGO 0x203
618  86.435195     4e.00.0b -> b6.02.00     FC ELS LOGO 0x213
619  86.435220     4e.00.0b -> 18.03.00     FC ELS LOGO 0x223
620  86.435244     4e.00.0b -> 18.02.00     FC ELS LOGO 0x233
621  86.435267     4e.00.0b -> 18.01.00     FC ELS LOGO 0x243
622  86.435349     00.00.00 -> ff.ff.fe     FC ELS FLOGI 0x203
623  86.435549     ff.ff.fc -> 4e.00.0b     FC ELS ACC (LOGO) 0x203
624  86.438721     ff.ff.fe -> 4e.00.0b     FC ELS ACC (FLOGI) 0x203
625  86.442059     18.03.00 -> 4e.00.0b     FC ELS ACC (LOGO) 0x223
626  86.443683     b6.02.00 -> 4e.00.0b     FC ELS ACC (LOGO) 0x213
627  86.447693     18.01.00 -> 4e.00.0b     FC ELS ACC (LOGO) 0x243
628  86.453499     18.02.00 -> 4e.00.0b     FC ELS ACC (LOGO) 0x233

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Reviewed-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>

drivers/scsi/libfc/fc_exch.c

@@ -494,6 +494,9 @@ static int fc_seq_send(struct fc_lport *lport, struct fc_seq *sp,
 	 */
 	error = lport->tt.frame_send(lport, fp);
 
+	if (fh->fh_type == FC_TYPE_BLS)
+		return error;
+
 	/*
 	 * Update the exchange and sequence flags,
 	 * assuming all frames for the sequence have been sent.
@@ -575,42 +578,35 @@ static void fc_seq_set_resp(struct fc_seq *sp,
 }
 
 /**
- * fc_seq_exch_abort() - Abort an exchange and sequence
- * @req_sp:	The sequence to be aborted
+ * fc_exch_abort_locked() - Abort an exchange
+ * @ep:	The exchange to be aborted
  * @timer_msec: The period of time to wait before aborting
  *
- * Generally called because of a timeout or an abort from the upper layer.
+ * Locking notes:  Called with exch lock held
+ *
+ * Return value: 0 on success else error code
  */
-static int fc_seq_exch_abort(const struct fc_seq *req_sp,
-			     unsigned int timer_msec)
+static int fc_exch_abort_locked(struct fc_exch *ep,
+				unsigned int timer_msec)
 {
 	struct fc_seq *sp;
-	struct fc_exch *ep;
 	struct fc_frame *fp;
 	int error;
 
-	ep = fc_seq_exch(req_sp);
-
-	spin_lock_bh(&ep->ex_lock);
 	if (ep->esb_stat & (ESB_ST_COMPLETE | ESB_ST_ABNORMAL) ||
-	    ep->state & (FC_EX_DONE | FC_EX_RST_CLEANUP)) {
-		spin_unlock_bh(&ep->ex_lock);
+	    ep->state & (FC_EX_DONE | FC_EX_RST_CLEANUP))
 		return -ENXIO;
-	}
 
 	/*
 	 * Send the abort on a new sequence if possible.
 	 */
 	sp = fc_seq_start_next_locked(&ep->seq);
-	if (!sp) {
-		spin_unlock_bh(&ep->ex_lock);
+	if (!sp)
 		return -ENOMEM;
-	}
 
 	ep->esb_stat |= ESB_ST_SEQ_INIT | ESB_ST_ABNORMAL;
 	if (timer_msec)
 		fc_exch_timer_set_locked(ep, timer_msec);
-	spin_unlock_bh(&ep->ex_lock);
 
 	/*
 	 * If not logged into the fabric, don't send ABTS but leave
@@ -632,6 +628,28 @@ static int fc_seq_exch_abort(const struct fc_seq *req_sp,
 	return error;
 }
 
+/**
+ * fc_seq_exch_abort() - Abort an exchange and sequence
+ * @req_sp:	The sequence to be aborted
+ * @timer_msec: The period of time to wait before aborting
+ *
+ * Generally called because of a timeout or an abort from the upper layer.
+ *
+ * Return value: 0 on success else error code
+ */
+static int fc_seq_exch_abort(const struct fc_seq *req_sp,
+			     unsigned int timer_msec)
+{
+	struct fc_exch *ep;
+	int error;
+
+	ep = fc_seq_exch(req_sp);
+	spin_lock_bh(&ep->ex_lock);
+	error = fc_exch_abort_locked(ep, timer_msec);
+	spin_unlock_bh(&ep->ex_lock);
+	return error;
+}
+
 /**
  * fc_exch_timeout() - Handle exchange timer expiration
  * @work: The work_struct identifying the exchange that timed out
@@ -1715,6 +1733,7 @@ static void fc_exch_reset(struct fc_exch *ep)
 	int rc = 1;
 
 	spin_lock_bh(&ep->ex_lock);
+	fc_exch_abort_locked(ep, 0);
 	ep->state |= FC_EX_RST_CLEANUP;
 	if (cancel_delayed_work(&ep->timeout_work))
 		atomic_dec(&ep->ex_refcnt);	/* drop hold for timer */

drivers/scsi/libfc/fc_lport.c

@@ -88,6 +88,7 @@
  */
 
 #include <linux/timer.h>
+#include <linux/delay.h>
 #include <linux/slab.h>
 #include <asm/unaligned.h>
 
@@ -1029,8 +1030,16 @@ static void fc_lport_enter_reset(struct fc_lport *lport)
 			   FCH_EVT_LIPRESET, 0);
 	fc_vports_linkchange(lport);
 	fc_lport_reset_locked(lport);
-	if (lport->link_up)
+	if (lport->link_up) {
+		/*
+		 * Wait upto resource allocation time out before
+		 * doing re-login since incomplete FIP exchanged
+		 * from last session may collide with exchanges
+		 * in new session.
+		 */
+		msleep(lport->r_a_tov);
 		fc_lport_enter_flogi(lport);
+	}
 }
 
 /**