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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: Hannes Reinecke <hare@suse.com>
Reviewed-by: Bart Van Assche <bart.vanassche@sandisk.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Hannes Reinecke 2016-10-13 15:10:50 +02:00 committed by Martin K. Petersen
parent b73aa56ee9
commit 9ca1e182b9
3 changed files with 30 additions and 17 deletions
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33
drivers/scsi/libfc/fc_exch.c
View File

@ -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 (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);
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;

13
drivers/scsi/libfc/fc_fcp.c
View File

@ -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;

1
include/scsi/libfc.h
View File

@ -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