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[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: 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>
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1 changed files with 15 additions and 8 deletions
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@ -415,9 +415,9 @@ static void fc_exch_timeout(struct work_struct *work)
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e_stat = ep->esb_stat;
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if (e_stat & ESB_ST_COMPLETE) {
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ep->esb_stat = e_stat & ~ESB_ST_REC_QUAL;
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spin_unlock_bh(&ep->ex_lock);
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if (e_stat & ESB_ST_REC_QUAL)
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fc_exch_rrq(ep);
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spin_unlock_bh(&ep->ex_lock);
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goto done;
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} else {
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resp = ep->resp;
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@ -1624,14 +1624,14 @@ static void fc_exch_rrq(struct fc_exch *ep)
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struct fc_lport *lp;
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struct fc_els_rrq *rrq;
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struct fc_frame *fp;
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struct fc_seq *rrq_sp;
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u32 did;
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lp = ep->lp;
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fp = fc_frame_alloc(lp, sizeof(*rrq));
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if (!fp)
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return;
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goto retry;
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rrq = fc_frame_payload_get(fp, sizeof(*rrq));
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memset(rrq, 0, sizeof(*rrq));
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rrq->rrq_cmd = ELS_RRQ;
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@ -1647,13 +1647,20 @@ static void fc_exch_rrq(struct fc_exch *ep)
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fc_host_port_id(lp->host), FC_TYPE_ELS,
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FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);
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rrq_sp = fc_exch_seq_send(lp, fp, fc_exch_rrq_resp, NULL, ep,
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lp->e_d_tov);
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if (!rrq_sp) {
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ep->esb_stat |= ESB_ST_REC_QUAL;
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fc_exch_timer_set_locked(ep, ep->r_a_tov);
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if (fc_exch_seq_send(lp, fp, fc_exch_rrq_resp, NULL, ep, lp->e_d_tov))
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return;
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retry:
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spin_lock_bh(&ep->ex_lock);
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if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE)) {
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spin_unlock_bh(&ep->ex_lock);
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/* drop hold for rec qual */
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fc_exch_release(ep);
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return;
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}
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ep->esb_stat |= ESB_ST_REC_QUAL;
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fc_exch_timer_set_locked(ep, ep->r_a_tov);
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spin_unlock_bh(&ep->ex_lock);
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}
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