cxgb3i: use kref to track ddp usage

The iscsi ddp functionality could be used by multiple iscsi entities,
add a refcnt to keep track of it, so we would not release it pre-maturely.

Signed-off-by: Karen Xie <kxie@chelsio.com>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>

2 files changed, 35 insertions, 21 deletions

diff --git a/drivers/scsi/cxgb3i/cxgb3i_ddp.c b/drivers/scsi/cxgb3i/cxgb3i_ddp.c
index 99c912547902..8eb2848403f4 100644
--- a/drivers/scsi/cxgb3i/cxgb3i_ddp.c
+++ b/drivers/scsi/cxgb3i/cxgb3i_ddp.c
@@ -598,30 +598,40 @@ int cxgb3i_adapter_ddp_info(struct t3cdev *tdev,
  * release all the resource held by the ddp pagepod manager for a given
  * adapter if needed
  */
-void cxgb3i_ddp_cleanup(struct t3cdev *tdev)
+
+static void ddp_cleanup(struct kref *kref)
 {
+        struct cxgb3i_ddp_info *ddp = container_of(kref,
+                                                struct cxgb3i_ddp_info,
+                                                refcnt);
         int i = 0;
+
+        ddp_log_info("kref release ddp 0x%p, t3dev 0x%p.\n", ddp, ddp->tdev);
+
+        ddp->tdev->ulp_iscsi = NULL;
+        while (i < ddp->nppods) {
+                struct cxgb3i_gather_list *gl = ddp->gl_map[i];
+                if (gl) {
+                        int npods = (gl->nelem + PPOD_PAGES_MAX - 1)
+                                        >> PPOD_PAGES_SHIFT;
+                        ddp_log_info("t3dev 0x%p, ddp %d + %d.\n",
+                                        ddp->tdev, i, npods);
+                        kfree(gl);
+                        ddp_free_gl_skb(ddp, i, npods);
+                        i += npods;
+                } else
+                        i++;
+        }
+        cxgb3i_free_big_mem(ddp);
+}
+
+void cxgb3i_ddp_cleanup(struct t3cdev *tdev)
+{
         struct cxgb3i_ddp_info *ddp = (struct cxgb3i_ddp_info *)tdev->ulp_iscsi;
 
         ddp_log_info("t3dev 0x%p, release ddp 0x%p.\n", tdev, ddp);
-
-        if (ddp) {
-                tdev->ulp_iscsi = NULL;
-                while (i < ddp->nppods) {
-                        struct cxgb3i_gather_list *gl = ddp->gl_map[i];
-                        if (gl) {
-                                int npods = (gl->nelem + PPOD_PAGES_MAX - 1)
-                                                >> PPOD_PAGES_SHIFT;
-                                ddp_log_info("t3dev 0x%p, ddp %d + %d.\n",
-                                                tdev, i, npods);
-                                kfree(gl);
-                                ddp_free_gl_skb(ddp, i, npods);
-                                i += npods;
-                        } else
-                                i++;
-                }
-                cxgb3i_free_big_mem(ddp);
-        }
+        if (ddp)
+                kref_put(&ddp->refcnt, ddp_cleanup);
 }
 
 /**
@@ -631,12 +641,13 @@ void cxgb3i_ddp_cleanup(struct t3cdev *tdev)
  */
 static void ddp_init(struct t3cdev *tdev)
 {
-        struct cxgb3i_ddp_info *ddp;
+        struct cxgb3i_ddp_info *ddp = tdev->ulp_iscsi;
         struct ulp_iscsi_info uinfo;
         unsigned int ppmax, bits;
         int i, err;
 
-        if (tdev->ulp_iscsi) {
+        if (ddp) {
+                kref_get(&ddp->refcnt);
                 ddp_log_warn("t3dev 0x%p, ddp 0x%p already set up.\n",
                                 tdev, tdev->ulp_iscsi);
                 return;
@@ -670,6 +681,7 @@ static void ddp_init(struct t3cdev *tdev)
                                           ppmax *
                                           sizeof(struct cxgb3i_gather_list *));
         spin_lock_init(&ddp->map_lock);
+        kref_init(&ddp->refcnt);
 
         ddp->tdev = tdev;
         ddp->pdev = uinfo.pdev;
diff --git a/drivers/scsi/cxgb3i/cxgb3i_ddp.h b/drivers/scsi/cxgb3i/cxgb3i_ddp.h
index 0d296de7cf32..87dd56b422bf 100644
--- a/drivers/scsi/cxgb3i/cxgb3i_ddp.h
+++ b/drivers/scsi/cxgb3i/cxgb3i_ddp.h
@@ -54,6 +54,7 @@ struct cxgb3i_gather_list {
  * struct cxgb3i_ddp_info - cxgb3i direct data placement for pdu payload
  *
  * @list:       list head to link elements
+ * @refcnt:     ref. count
  * @tdev:       pointer to t3cdev used by cxgb3 driver
  * @max_txsz:   max tx packet size for ddp
  * @max_rxsz:   max rx packet size for ddp
@@ -70,6 +71,7 @@ struct cxgb3i_gather_list {
  */
 struct cxgb3i_ddp_info {
         struct list_head list;
+        struct kref refcnt;
         struct t3cdev *tdev;
         struct pci_dev *pdev;
         unsigned int max_txsz;