RDS: Assume recv->r_frag is always NULL in refill_one()

refill_one() should never be called on a recv struct that
doesn't need a new r_frag allocated. Add a WARN and remove
conditional around r_frag alloc code.

Also, add a comment to explain why r_ibinc may or may not
need refilling.

Signed-off-by: Andy Grover <andy.grover@oracle.com>

diff --git a/net/rds/ib_recv.c b/net/rds/ib_recv.c
index f6dbf16..5c7e6ac 100644 (file)
--- a/net/rds/ib_recv.c
+++ b/net/rds/ib_recv.c
@@ -126,6 +126,10 @@ static int rds_ib_recv_refill_one(struct rds_connection *conn,
        struct ib_sge *sge;
        int ret = -ENOMEM;
 
+       /*
+        * ibinc was taken from recv if recv contained the start of a message.
+        * recvs that were continuations will still have this allocated.
+        */
        if (!recv->r_ibinc) {
                if (!atomic_add_unless(&rds_ib_allocation, 1, rds_ib_sysctl_max_recv_allocation)) {
                        rds_ib_stats_inc(s_ib_rx_alloc_limit);
@@ -140,19 +144,18 @@ static int rds_ib_recv_refill_one(struct rds_connection *conn,
                rds_inc_init(&recv->r_ibinc->ii_inc, conn, conn->c_faddr);
        }
 
-       if (!recv->r_frag) {
-               recv->r_frag = kmem_cache_alloc(rds_ib_frag_slab, GFP_NOWAIT);
-               if (!recv->r_frag)
-                       goto out;
-               INIT_LIST_HEAD(&recv->r_frag->f_item);
-               sg_init_table(&recv->r_frag->f_sg, 1);
-               ret = rds_page_remainder_alloc(&recv->r_frag->f_sg,
-                                              RDS_FRAG_SIZE, GFP_NOWAIT);
-               if (ret) {
-                       kmem_cache_free(rds_ib_frag_slab, recv->r_frag);
-                       recv->r_frag = NULL;
-                       goto out;
-               }
+       WARN_ON(recv->r_frag); /* leak! */
+       recv->r_frag = kmem_cache_alloc(rds_ib_frag_slab, GFP_NOWAIT);
+       if (!recv->r_frag)
+               goto out;
+       INIT_LIST_HEAD(&recv->r_frag->f_item);
+       sg_init_table(&recv->r_frag->f_sg, 1);
+       ret = rds_page_remainder_alloc(&recv->r_frag->f_sg,
+                                      RDS_FRAG_SIZE, GFP_NOWAIT);
+       if (ret) {
+               kmem_cache_free(rds_ib_frag_slab, recv->r_frag);
+               recv->r_frag = NULL;
+               goto out;
        }
 
        ret = ib_dma_map_sg(ic->i_cm_id->device, &recv->r_frag->f_sg,