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fcoe: close race on link speed detection in fcoe code 

When creating an fcoe interfce, we call fcoe_link_speed_update before we add the
lports fcoe interface to the fc_hostlist.  Since network device events like
NETDEV_CHANGE are only processed if an fcoe interface is found with an
underlying netdev that matches the netdev of the event.  Since this processing
in fcoe_device_notification is how link_speed changes get communicated to the
libfc  code (via fcoe_link_speed_update), we have a race condition - if a
NETDEV_CHANGE event is sent after the call to fcoe_link_speed_update in
fcoe_netdev_config, but before we add the interface to the fc_hostlist, we will
loose the event and attributes like /sys/class/fc_host/hostX/speed will not get
updated properly.

Fix this by moving the add to the fc_hostlist above the serialized call to
fcoe_netdev_config, ensuring that we catch netdev envents before we make a
direct call to fcoe_link_speed_update.

Also use this opportunity to clean up access to the fc_hostlist a bit by
creating a fcoe_hostlist_del accessor and replacing the cleanup in fcoe_exit to
use it properly.

Tested by myself successfully

[ Comment over 80 chars broken into multi-line by Robert Love to
  satisfy checkpatch.pl ]

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
Reviewed-by: Yi Zou <yi.zou@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
This commit is contained in:
Neil Horman 2013-01-15 14:34:40 -05:00 committed by Robert Love
parent cf02820041
commit f9184df3b9
1 changed files with 27 additions and 4 deletions
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31
drivers/scsi/fcoe/fcoe.c
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@ -86,6 +86,7 @@ static int fcoe_link_ok(struct fc_lport *);
static struct fc_lport *fcoe_hostlist_lookup(const struct net_device *);
static int fcoe_hostlist_add(const struct fc_lport *);
static void fcoe_hostlist_del(const struct fc_lport *);
static int fcoe_device_notification(struct notifier_block *, ulong, void *);
static void fcoe_dev_setup(void);
@ -1119,6 +1120,12 @@ static struct fc_lport *fcoe_if_create(struct fcoe_interface *fcoe,
port->min_queue_depth = FCOE_MIN_QUEUE_DEPTH;
INIT_WORK(&port->destroy_work, fcoe_destroy_work);
/*
* Need to add the lport to the hostlist
* so we catch NETDEV_CHANGE events.
*/
fcoe_hostlist_add(lport);
/* configure a fc_lport including the exchange manager */
rc = fcoe_lport_config(lport);
if (rc) {
@ -1190,6 +1197,7 @@ static struct fc_lport *fcoe_if_create(struct fcoe_interface *fcoe,
out_lp_destroy:
fc_exch_mgr_free(lport);
out_host_put:
fcoe_hostlist_del(lport);
scsi_host_put(lport->host);
out:
return ERR_PTR(rc);
@ -2313,9 +2321,6 @@ static int _fcoe_create(struct net_device *netdev, enum fip_state fip_mode,
/* setup DCB priority attributes. */
fcoe_dcb_create(fcoe);
/* add to lports list */
fcoe_hostlist_add(lport);
/* start FIP Discovery and FLOGI */
lport->boot_time = jiffies;
fc_fabric_login(lport);
@ -2523,6 +2528,24 @@ static int fcoe_hostlist_add(const struct fc_lport *lport)
return 0;
}
/**
* fcoe_hostlist_del() - Remove the FCoE interface identified by a local
* port to the hostlist
* @lport: The local port that identifies the FCoE interface to be added
*
* Locking: must be called with the RTNL mutex held
*
*/
static void fcoe_hostlist_del(const struct fc_lport *lport)
{
struct fcoe_interface *fcoe;
struct fcoe_port *port;
port = lport_priv(lport);
fcoe = port->priv;
list_del(&fcoe->list);
return;
}
static struct fcoe_transport fcoe_sw_transport = {
.name = {FCOE_TRANSPORT_DEFAULT},
@ -2613,9 +2636,9 @@ static void __exit fcoe_exit(void)
/* releases the associated fcoe hosts */
rtnl_lock();
list_for_each_entry_safe(fcoe, tmp, &fcoe_hostlist, list) {
list_del(&fcoe->list);
ctlr = fcoe_to_ctlr(fcoe);
port = lport_priv(ctlr->lp);
fcoe_hostlist_del(port->lport);
queue_work(fcoe_wq, &port->destroy_work);
}
rtnl_unlock();