[SCSI] libfc: fix a circular locking warning during sending RRQ (a0cc1ecc) · Commits · 戴 / test

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:

Vasu Dev <vasu.dev@intel.com> Signed-off-by:

Robert Love <robert.w.love@intel.com> Signed-off-by:

James Bottomley <James.Bottomley@HansenPartnership.com>

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);
		}

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