[SCSI] fcoe, libfc: adds exchange manager(EM) anchor list per lport and related APIs

Adds EM list using a anchor struct fc_exch_mgr_anchor, anchor is used
to allow same EM instance sharing across more than one lport on a eth
device, this implementation is per discussed design posted at
http://www.open-fcoe.org/pipermail/devel/2009-June/002566.html.

The shared EM is required for multiple lports on eth device when
using multiple VLANs or NPIV.

Adds fc_exch_mgr_add API to add a EM to the lport and fc_exch_mgr_del
API to delete previously added EM.

Also adds function fc_exch_mgr_destroy() to destroy allocated EM.
The kref is added to the EM to keep track of EM usage count, the EM is
destroyed when no longer in use upon kref reaching to zero.

The caller can specify match function to fc_exch_mgr_add, this
will be used in determining exchange allocation from its EM or not.

Moved calling of fcoe_em_config below fcoe_libfc_config calling,
so that list head lp->ema_list is initialized before configuring
EM.

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

2 files changed, 49 insertions, 0 deletions

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
index cab54996375..f1fa2b196e9 100644
--- a/drivers/scsi/libfc/fc_exch.c
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -55,6 +55,7 @@ static struct kmem_cache *fc_em_cachep;        /* cache for exchanges */
  */
 struct fc_exch_mgr {
         enum fc_class   class;          /* default class for sequences */
+        struct kref     kref;           /* exchange mgr reference count */
         spinlock_t      em_lock;        /* exchange manager lock,
                                            must be taken before ex_lock */
         u16             last_xid;       /* last allocated exchange ID */
@@ -84,6 +85,12 @@ struct fc_exch_mgr {
 };
 #define fc_seq_exch(sp) container_of(sp, struct fc_exch, seq)
 
+struct fc_exch_mgr_anchor {
+        struct list_head ema_list;
+        struct fc_exch_mgr *mp;
+        bool (*match)(struct fc_frame *);
+};
+
 static void fc_exch_rrq(struct fc_exch *);
 static void fc_seq_ls_acc(struct fc_seq *);
 static void fc_seq_ls_rjt(struct fc_seq *, enum fc_els_rjt_reason,
@@ -1729,6 +1736,47 @@ reject:
         fc_frame_free(fp);
 }
 
+struct fc_exch_mgr_anchor *fc_exch_mgr_add(struct fc_lport *lport,
+                                           struct fc_exch_mgr *mp,
+                                           bool (*match)(struct fc_frame *))
+{
+        struct fc_exch_mgr_anchor *ema;
+
+        ema = kmalloc(sizeof(*ema), GFP_ATOMIC);
+        if (!ema)
+                return ema;
+
+        ema->mp = mp;
+        ema->match = match;
+        /* add EM anchor to EM anchors list */
+        list_add_tail(&ema->ema_list, &lport->ema_list);
+        kref_get(&mp->kref);
+        return ema;
+}
+EXPORT_SYMBOL(fc_exch_mgr_add);
+
+static void fc_exch_mgr_destroy(struct kref *kref)
+{
+        struct fc_exch_mgr *mp = container_of(kref, struct fc_exch_mgr, kref);
+
+        /*
+         * The total exch count must be zero
+         * before freeing exchange manager.
+         */
+        WARN_ON(mp->total_exches != 0);
+        mempool_destroy(mp->ep_pool);
+        kfree(mp);
+}
+
+void fc_exch_mgr_del(struct fc_exch_mgr_anchor *ema)
+{
+        /* remove EM anchor from EM anchors list */
+        list_del(&ema->ema_list);
+        kref_put(&ema->mp->kref, fc_exch_mgr_destroy);
+        kfree(ema);
+}
+EXPORT_SYMBOL(fc_exch_mgr_del);
+
 struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lp,
                                       enum fc_class class,
                                       u16 min_xid, u16 max_xid)
diff --git a/drivers/scsi/libfc/fc_lport.c b/drivers/scsi/libfc/fc_lport.c
index a430335ebf5..ca8ea264b68 100644
--- a/drivers/scsi/libfc/fc_lport.c
+++ b/drivers/scsi/libfc/fc_lport.c
@@ -1618,6 +1618,7 @@ int fc_lport_init(struct fc_lport *lport)
         if (lport->link_supported_speeds & FC_PORTSPEED_10GBIT)
                 fc_host_supported_speeds(lport->host) |= FC_PORTSPEED_10GBIT;
 
+        INIT_LIST_HEAD(&lport->ema_list);
         return 0;
 }
 EXPORT_SYMBOL(fc_lport_init);