Commit 9ca1e182 authored by Hannes Reinecke's avatar Hannes Reinecke Committed by Martin K. Petersen
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scsi: libfc: quarantine timed out xids 



When a sequence times out we have no idea what happened to the
frame. And we do not know if we will ever receive the frame.
Hence we cannot re-use the xid as we would risk data corruption
if the xid had been re-used and the timed out frame would be
received after that.
So we need to quarantine the xid until the lport is reset.
Yes, I know this will (eventually) deplete the xid pool.
But for now it's the safest method.

Signed-off-by: default avatarHannes Reinecke <hare@suse.com>
Reviewed-by: default avatarBart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: default avatarMartin K. Petersen <martin.petersen@oracle.com>
parent b73aa56e

drivers/scsi/libfc/fc_exch.c

+22 −11
Original line number Diff line number Diff line
@@ -94,6 +94,7 @@ struct fc_exch_pool { 
struct fc_exch_mgr {

	struct fc_exch_pool __percpu *pool;

	mempool_t	*ep_pool;

	struct fc_lport	*lport;

	enum fc_class	class;

	struct kref	kref;

	u16		min_xid;
@@ -408,6 +409,8 @@ static int fc_exch_done_locked(struct fc_exch *ep) 
	return rc;

}



static struct fc_exch fc_quarantine_exch;



/**

 * fc_exch_ptr_get() - Return an exchange from an exchange pool

 * @pool:  Exchange Pool to get an exchange from
@@ -452,14 +455,17 @@ static void fc_exch_delete(struct fc_exch *ep) 


	/* update cache of free slot */

	index = (ep->xid - ep->em->min_xid) >> fc_cpu_order;

	if (!(ep->state & FC_EX_QUARANTINE)) {

		if (pool->left == FC_XID_UNKNOWN)

			pool->left = index;

		else if (pool->right == FC_XID_UNKNOWN)

			pool->right = index;

		else

			pool->next_index = index;



		fc_exch_ptr_set(pool, index, NULL);

	} else {

		fc_exch_ptr_set(pool, index, &fc_quarantine_exch);

	}

	list_del(&ep->ex_list);

	spin_unlock_bh(&pool->lock);

	fc_exch_release(ep);	/* drop hold for exch in mp */
@@ -921,14 +927,14 @@ static struct fc_exch *fc_exch_alloc(struct fc_lport *lport, 
 */

static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid)

{

	struct fc_lport *lport = mp->lport;

	struct fc_exch_pool *pool;

	struct fc_exch *ep = NULL;

	u16 cpu = xid & fc_cpu_mask;



	if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) {

		printk_ratelimited(KERN_ERR

			"libfc: lookup request for XID = %d, "

			"indicates invalid CPU %d\n", xid, cpu);

		pr_err("host%u: lport %6.6x: xid %d invalid CPU %d\n:",

		       lport->host->host_no, lport->port_id, xid, cpu);

		return NULL;

	}
@@ -936,6 +942,10 @@ static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid) 
		pool = per_cpu_ptr(mp->pool, cpu);

		spin_lock_bh(&pool->lock);

		ep = fc_exch_ptr_get(pool, (xid - mp->min_xid) >> fc_cpu_order);

		if (ep == &fc_quarantine_exch) {

			FC_LPORT_DBG(lport, "xid %x quarantined\n", xid);

			ep = NULL;

		}

		if (ep) {

			WARN_ON(ep->xid != xid);

			fc_exch_hold(ep);
@@ -2434,6 +2444,7 @@ struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lport, 
		return NULL;



	mp->class = class;

	mp->lport = lport;

	/* adjust em exch xid range for offload */

	mp->min_xid = min_xid;

drivers/scsi/libfc/fc_fcp.c

+7 −6
Original line number Diff line number Diff line
@@ -1529,13 +1529,14 @@ static void fc_fcp_rec_resp(struct fc_seq *seq, struct fc_frame *fp, void *arg) 
				   fsp->rport->port_id, rjt->er_reason,

				   rjt->er_explan);

			/*

			 * If no data transfer, the command frame got dropped

			 * so we just retry.  If data was transferred, we

			 * lost the response but the target has no record,

			 * so we abort and retry.

			 * If response got lost or is stuck in the

			 * queue somewhere we have no idea if and when

			 * the response will be received. So quarantine

			 * the xid and retry the command.

			 */

			if (rjt->er_explan == ELS_EXPL_OXID_RXID &&

			    fsp->xfer_len == 0) {

			if (rjt->er_explan == ELS_EXPL_OXID_RXID) {

				struct fc_exch *ep = fc_seq_exch(fsp->seq_ptr);

				ep->state |= FC_EX_QUARANTINE;

				fsp->state |= FC_SRB_ABORTED;

				fc_fcp_retry_cmd(fsp, FC_TRANS_RESET);

				break;

include/scsi/libfc.h

+1 −0
Original line number Diff line number Diff line
@@ -390,6 +390,7 @@ struct fc_seq { 


#define FC_EX_DONE		(1 << 0) /* ep is completed */

#define FC_EX_RST_CLEANUP	(1 << 1) /* reset is forcing completion */

#define FC_EX_QUARANTINE	(1 << 2) /* exch is quarantined */



/**

 * struct fc_exch - Fibre Channel Exchange