[PATCH 17/22] fcoe: modifies fcoe_hostlist_lock uses as prep work to add shared offload EM

Robert Love
2009-07-30T00:05:15Z

From: Vasu Dev <vasu.dev@intel.com>

Modifies fcoe_hostlist_lock uses such that a new EM allocation in
fcoe_em_config and adding new fcoe_softc using fcoe_hostlist_add
are atomic, this is to ensure that a shared offload EM gets allocated
only once per eth device for its all lports.

Signed-off-by: Vasu Dev <vasu.dev@intel.com>
Signed-off-by: Robert Love <robert.w.love@intel.com>
---

drivers/scsi/fcoe/fcoe.c | 26 ++++++++++++++++++--------
1 files changed, 18 insertions(+), 8 deletions(-)

diff --git a/drivers/scsi/fcoe/fcoe.c b/drivers/scsi/fcoe/fcoe.c
index ebf2e20..86410b9 100644
--- a/drivers/scsi/fcoe/fcoe.c
+++ b/drivers/scsi/fcoe/fcoe.c
@@ -419,6 +419,8 @@ static int fcoe_shost_config(struct fc_lport *lp, struct Scsi_Host *shost,
* fcoe_em_config() - allocates em for this lport
* @lp: the port 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)
@@ -607,6 +609,13 @@ static int fcoe_if_create(struct net_device *netdev)
goto out_lp_destroy;
}

+ /*
+ * fcoe_em_alloc() and fcoe_hostlist_add() both
+ * need to be atomic under fcoe_hostlist_lock
+ * since fcoe_em_alloc() looks for an existing EM
+ * instance on host list updated by fcoe_hostlist_add().
+ */
+ write_lock(&fcoe_hostlist_lock);
/* lport exch manager allocation */
rc = fcoe_em_config(lp);
if (rc) {
@@ -617,6 +626,7 @@ static int fcoe_if_create(struct net_device *netdev)

/* add to lports list */
fcoe_hostlist_add(lp);
+ write_unlock(&fcoe_hostlist_lock);

lp->boot_time = jiffies;

@@ -1720,6 +1730,8 @@ int fcoe_reset(struct Scsi_Host *shost)
* fcoe_hostlist_lookup_softc() - 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_softc
*/
static struct fcoe_softc *
@@ -1727,14 +1739,10 @@ fcoe_hostlist_lookup_softc(const struct net_device *dev)
{
struct fcoe_softc *fc;

- read_lock(&fcoe_hostlist_lock);
list_for_each_entry(fc, &fcoe_hostlist, list) {
- if (fc->real_dev == dev) {
- read_unlock(&fcoe_hostlist_lock);
+ if (fc->real_dev == dev)
return fc;
- }
}
- read_unlock(&fcoe_hostlist_lock);
return NULL;
}

@@ -1748,7 +1756,9 @@ struct fc_lport *fcoe_hostlist_lookup(const struct net_device *netdev)
{
struct fcoe_softc *fc;

+ read_lock(&fcoe_hostlist_lock);
fc = fcoe_hostlist_lookup_softc(netdev);
+ read_unlock(&fcoe_hostlist_lock);

return (fc) ? fc->ctlr.lp : NULL;
}
@@ -1757,6 +1767,8 @@ struct fc_lport *fcoe_hostlist_lookup(const struct net_device *netdev)
* fcoe_hostlist_add() - Add a lport to lports list
* @lp: ptr to the fc_lport to be added
*
+ * Called with write fcoe_hostlist_lock held.
+ *
* Returns: 0 for success
*/
int fcoe_hostlist_add(const struct fc_lport *lp)
@@ -1766,9 +1778,7 @@ int fcoe_hostlist_add(const struct fc_lport *lp)
fc = fcoe_hostlist_lookup_softc(fcoe_netdev(lp));
if (!fc) {
fc = lport_priv(lp);
- write_lock_bh(&fcoe_hostlist_lock);
list_add_tail(&fc->list, &fcoe_hostlist);
- write_unlock_bh(&fcoe_hostlist_lock);
}
return 0;
}
@@ -1783,9 +1793,9 @@ int fcoe_hostlist_remove(const struct fc_lport *lp)
{
struct fcoe_softc *fc;

+ write_lock_bh(&fcoe_hostlist_lock);
fc = fcoe_hostlist_lookup_softc(fcoe_netdev(lp));
BUG_ON(!fc);
- write_lock_bh(&fcoe_hostlist_lock);
list_del(&fc->list);
write_unlock_bh(&fcoe_hostlist_lock);