Commit 82035511 authored Dec 15, 2020 by Javed Hasan Committed by Greg Kroah-Hartman Feb 10, 2021

scsi: libfc: Avoid invoking response handler twice if ep is already completed

[ Upstream commit b2b0f16fa65e910a3ec8771206bb49ee87a54ac5 ]

A race condition exists between the response handler getting called because
of exchange_mgr_reset() (which clears out all the active XIDs) and the
response we get via an interrupt.

Sequence of events:

	 rport ba0200: Port timeout, state PLOGI
	 rport ba0200: Port entered PLOGI state from PLOGI state
	 xid 1052: Exchange timer armed : 20000 msecs      xid timer armed here
	 rport ba0200: Received LOGO request while in state PLOGI
	 rport ba0200: Delete port
	 rport ba0200: work event 3
	 rport ba0200: lld callback ev 3
	 bnx2fc: rport_event_hdlr: event = 3, port_id = 0xba0200
	 bnx2fc: ba0200 - rport not created Yet!!
	 /* Here we reset any outstanding exchanges before
	 freeing rport using the exch_mgr_reset() */
	 xid 1052: Exchange timer canceled
	 /* Here we got two responses for one xid */
	 xid 1052: invoking resp(), esb 20000000 state 3
	 xid 1052: invoking resp(), esb 20000000 state 3
	 xid 1052: fc_rport_plogi_resp() : ep->resp_active 2
	 xid 1052: fc_rport_plogi_resp() : ep->resp_active 2

Skip the response if the exchange is already completed.

Link: https://lore.kernel.org/r/20201215194731.2326-1-jhasan@marvell.com


Signed-off-by: Javed Hasan <jhasan@marvell.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>

parent f42ee7b5

drivers/scsi/libfc/fc_exch.c

+14 −2

Original line number	Diff line number	Diff line
		@@ -1577,8 +1577,13 @@ static void fc_exch_recv_seq_resp(struct fc_exch_mgr mp, struct fc_frame fp)
		rc = fc_exch_done_locked(ep);
		WARN_ON(fc_seq_exch(sp) != ep);
		spin_unlock_bh(&ep->ex_lock);
		if (!rc)
		if (!rc) {
		fc_exch_delete(ep);
		} else {
		FC_EXCH_DBG(ep, "ep is completed already,"
		"hence skip calling the resp\n");
		goto skip_resp;
		}
		}

		/*
		@@ -1597,6 +1602,7 @@ static void fc_exch_recv_seq_resp(struct fc_exch_mgr mp, struct fc_frame fp)
		if (!fc_invoke_resp(ep, sp, fp))
		fc_frame_free(fp);

		skip_resp:
		fc_exch_release(ep);
		return;
		rel:
		@@ -1841,10 +1847,16 @@ static void fc_exch_reset(struct fc_exch *ep)

		fc_exch_hold(ep);

		if (!rc)
		if (!rc) {
		fc_exch_delete(ep);
		} else {
		FC_EXCH_DBG(ep, "ep is completed already,"
		"hence skip calling the resp\n");
		goto skip_resp;
		}

		fc_invoke_resp(ep, sp, ERR_PTR(-FC_EX_CLOSED));
		skip_resp:
		fc_seq_set_resp(sp, NULL, ep->arg);
		fc_exch_release(ep);
		}