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Commit f95b35cf authored by Bart Van Assche's avatar Bart Van Assche Committed by Robert Love
Browse files

libfc: Reduce exchange lock contention in fc_exch_recv_abts() 



Reduce the time during which the exchange lock is held by allocating
a frame before obtaining the exchange lock.

Signed-off-by: default avatarBart Van Assche <bvanassche@acm.org>
Cc: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
parent cae7b6dd

drivers/scsi/libfc/fc_exch.c

+10 −8
Original line number Diff line number Diff line
@@ -1307,9 +1307,16 @@ static void fc_exch_recv_abts(struct fc_exch *ep, struct fc_frame *rx_fp) 


	if (!ep)

		goto reject;



	fp = fc_frame_alloc(ep->lp, sizeof(*ap));

	if (!fp)

		goto free;



	spin_lock_bh(&ep->ex_lock);

	if (ep->esb_stat & ESB_ST_COMPLETE) {

		spin_unlock_bh(&ep->ex_lock);



		fc_frame_free(fp);

		goto reject;

	}

	if (!(ep->esb_stat & ESB_ST_REC_QUAL)) {
@@ -1317,12 +1324,6 @@ static void fc_exch_recv_abts(struct fc_exch *ep, struct fc_frame *rx_fp) 
		fc_exch_hold(ep);		/* hold for REC_QUAL */

	}

	fc_exch_timer_set_locked(ep, ep->r_a_tov);



	fp = fc_frame_alloc(ep->lp, sizeof(*ap));

	if (!fp) {

		spin_unlock_bh(&ep->ex_lock);

		goto free;

	}

	fh = fc_frame_header_get(fp);

	ap = fc_frame_payload_get(fp, sizeof(*ap));

	memset(ap, 0, sizeof(*ap));
@@ -1338,13 +1339,14 @@ static void fc_exch_recv_abts(struct fc_exch *ep, struct fc_frame *rx_fp) 
	fc_seq_send_last(sp, fp, FC_RCTL_BA_ACC, FC_TYPE_BLS);

	ep->esb_stat |= ESB_ST_ABNORMAL;

	spin_unlock_bh(&ep->ex_lock);



free:

	fc_frame_free(rx_fp);

	return;



reject:

	fc_exch_send_ba_rjt(rx_fp, FC_BA_RJT_UNABLE, FC_BA_RJT_INV_XID);

free:

	fc_frame_free(rx_fp);

	goto free;

}



/**