Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit a0cc1ecc authored by Vasu Dev's avatar Vasu Dev Committed by James Bottomley
Browse files

[SCSI] libfc: fix a circular locking warning during sending RRQ 

Currently the fc_exch_rrq is called with fc_exch's ex_lock held.
The fc_exch_rrq allocates new exch and that requires taking
ex_lock again after EM lock. This locking order causes warning,
see more details on this warning at :-

 http://www.open-fcoe.org/pipermail/devel/2009-July/003251.html



This patch fixes this by dropping the ex_lock before calling
fc_exch_rrq().

The fc_exch_rrq needs to grab ex_lock lock again to schedule
RRQ retry and in the meanwhile fc_exch_reset could occur before
ex_lock is grabbed inside fc_exch_rrq. So to handle this case,
this patch adds additional check to detect fc_exch_reset after
ex_lock acquired and in case the fc_exch_reset occurred then
abandons the RRQ retry and releases the exch.

Signed-off-by: default avatarVasu Dev <vasu.dev@intel.com>
Signed-off-by: default avatarRobert Love <robert.w.love@intel.com>
Signed-off-by: default avatarJames Bottomley <James.Bottomley@HansenPartnership.com>
parent 16ed55f9

drivers/scsi/libfc/fc_exch.c

+15 −8
Original line number Diff line number Diff line
@@ -415,9 +415,9 @@ static void fc_exch_timeout(struct work_struct *work) 
	e_stat = ep->esb_stat;

	if (e_stat & ESB_ST_COMPLETE) {

		ep->esb_stat = e_stat & ~ESB_ST_REC_QUAL;

		spin_unlock_bh(&ep->ex_lock);

		if (e_stat & ESB_ST_REC_QUAL)

			fc_exch_rrq(ep);

		spin_unlock_bh(&ep->ex_lock);

		goto done;

	} else {

		resp = ep->resp;
@@ -1624,14 +1624,14 @@ static void fc_exch_rrq(struct fc_exch *ep) 
	struct fc_lport *lp;

	struct fc_els_rrq *rrq;

	struct fc_frame *fp;

	struct fc_seq *rrq_sp;

	u32 did;



	lp = ep->lp;



	fp = fc_frame_alloc(lp, sizeof(*rrq));

	if (!fp)

		return;

		goto retry;



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

	memset(rrq, 0, sizeof(*rrq));

	rrq->rrq_cmd = ELS_RRQ;
@@ -1647,13 +1647,20 @@ static void fc_exch_rrq(struct fc_exch *ep) 
		       fc_host_port_id(lp->host), FC_TYPE_ELS,

		       FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);



	rrq_sp = fc_exch_seq_send(lp, fp, fc_exch_rrq_resp, NULL, ep,

				  lp->e_d_tov);

	if (!rrq_sp) {

		ep->esb_stat |= ESB_ST_REC_QUAL;

		fc_exch_timer_set_locked(ep, ep->r_a_tov);

	if (fc_exch_seq_send(lp, fp, fc_exch_rrq_resp, NULL, ep, lp->e_d_tov))

		return;



retry:

	spin_lock_bh(&ep->ex_lock);

	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE)) {

		spin_unlock_bh(&ep->ex_lock);

		/* drop hold for rec qual */

		fc_exch_release(ep);

		return;

	}

	ep->esb_stat |= ESB_ST_REC_QUAL;

	fc_exch_timer_set_locked(ep, ep->r_a_tov);

	spin_unlock_bh(&ep->ex_lock);

}