[PATCH 23/64] fcoe: use rtnl mutex in place of hostlist lock

Robert Love
2009-08-25T21:00:27Z

From: Chris Leech <christopher.leech@intel.com>

This just cuts down on the number of locks we're dealing with, and
eliminates the need to take another lock in the netdev notifier.

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

drivers/scsi/fcoe/fcoe.c | 37 +++++++++++--------------------------
1 files changed, 11 insertions(+), 26 deletions(-)

diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index c0264a9..ac481ad 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -58,8 +58,8 @@ MODULE_PARM_DESC(ddp_min, "Minimum I/O size in bytes for " \
DEFINE_MUTEX(fcoe_config_mutex);

/* fcoe host list */
+/* must only by accessed under the RTNL mutex */
LIST_HEAD(fcoe_hostlist);
-DEFINE_RWLOCK(fcoe_hostlist_lock);
DEFINE_PER_CPU(struct fcoe_percpu_s, fcoe_percpu);

/* Function Prototypes */
@@ -527,8 +527,6 @@ bool fcoe_oem_match(struct fc_frame *fp)
* fcoe_em_config() - allocates em for this lport
* @lp: the fcoe that em is to allocated for
*
- * Called with write fcoe_hostlist_lock held.
- *
* Returns : 0 on success
*/
static inline int fcoe_em_config(struct fc_lport *lp)
@@ -1539,7 +1537,6 @@ static int fcoe_device_notification(struct notifier_block *notifier,
u32 mfs;
int rc = NOTIFY_OK;

- write_lock(&fcoe_hostlist_lock);
list_for_each_entry(fcoe, &fcoe_hostlist, list) {
if (fcoe->netdev == netdev) {
lp = fcoe->ctlr.lp;
@@ -1586,7 +1583,6 @@ static int fcoe_device_notification(struct notifier_block *notifier,
fcoe_clean_pending_queue(lp);
}
out:
- write_unlock(&fcoe_hostlist_lock);
return rc;
}

@@ -1643,16 +1639,14 @@ static int fcoe_destroy(const char *buffer, struct kernel_param *kp)
goto out_nodev;
}

- write_lock(&fcoe_hostlist_lock);
+ rtnl_lock();
fcoe = fcoe_hostlist_lookup_port(netdev);
if (!fcoe) {
- write_unlock(&fcoe_hostlist_lock);
+ rtnl_unlock();
rc = -ENODEV;
goto out_putdev;
}
list_del(&fcoe->list);
- write_unlock(&fcoe_hostlist_lock);
- rtnl_lock();
fcoe_interface_cleanup(fcoe);
rtnl_unlock();
fcoe_if_destroy(fcoe->ctlr.lp);
@@ -1870,9 +1864,8 @@ int fcoe_reset(struct Scsi_Host *shost)
* fcoe_hostlist_lookup_port() - find the corresponding lport by a given device
* @dev: this is currently ptr to net_device
*
- * Called with fcoe_hostlist_lock held.
- *
* Returns: NULL or the located fcoe_port
+ * Locking: must be called with the RNL mutex held
*/
static struct fcoe_interface *
fcoe_hostlist_lookup_port(const struct net_device *dev)
@@ -1891,15 +1884,13 @@ fcoe_hostlist_lookup_port(const struct net_device *dev)
* @netdev: ptr to net_device
*
* Returns: 0 for success
+ * Locking: must be called with the RTNL mutex held
*/
-struct fc_lport *fcoe_hostlist_lookup(const struct net_device *netdev)
+static struct fc_lport *fcoe_hostlist_lookup(const struct net_device *netdev)
{
struct fcoe_interface *fcoe;

- read_lock(&fcoe_hostlist_lock);
fcoe = fcoe_hostlist_lookup_port(netdev);
- read_unlock(&fcoe_hostlist_lock);
-
return (fcoe) ? fcoe->ctlr.lp : NULL;
}

@@ -1908,20 +1899,19 @@ struct fc_lport *fcoe_hostlist_lookup(const struct net_device *netdev)
* @lp: ptr to the fc_lport to be added
*
* Returns: 0 for success
+ * Locking: must be called with the RTNL mutex held
*/
-int fcoe_hostlist_add(const struct fc_lport *lport)
+static int fcoe_hostlist_add(const struct fc_lport *lport)
{
struct fcoe_interface *fcoe;
struct fcoe_port *port;

- write_lock_bh(&fcoe_hostlist_lock);
fcoe = fcoe_hostlist_lookup_port(fcoe_netdev(lport));
if (!fcoe) {
port = lport_priv(lport);
fcoe = port->fcoe;
list_add_tail(&fcoe->list, &fcoe_hostlist);
}
- write_unlock_bh(&fcoe_hostlist_lock);
return 0;
}

@@ -1979,7 +1969,6 @@ static void __exit fcoe_exit(void)
{
unsigned int cpu;
struct fcoe_interface *fcoe, *tmp;
- LIST_HEAD(local_list);
struct fcoe_port *port;

mutex_lock(&fcoe_config_mutex);
@@ -1987,18 +1976,14 @@ static void __exit fcoe_exit(void)
fcoe_dev_cleanup();

/* releases the associated fcoe hosts */
- write_lock_bh(&fcoe_hostlist_lock);
- list_splice_init(&fcoe_hostlist, &local_list);
- write_unlock_bh(&fcoe_hostlist_lock);
-
- list_for_each_entry_safe(fcoe, tmp, &local_list, list) {
+ rtnl_lock();
+ list_for_each_entry_safe(fcoe, tmp, &fcoe_hostlist, list) {
list_del(&fcoe->list);
port = lport_priv(fcoe->ctlr.lp);
- rtnl_lock();
fcoe_interface_cleanup(fcoe);
- rtnl_unlock();
schedule_work(&port->destroy_work);
}
+ rtnl_unlock();

unregister_hotcpu_notifier(&fcoe_cpu_notifier);