1 files changed, 38 insertions, 8 deletions

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index ab0d538a74ed..1099e99a53c4 100644
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -60,6 +60,8 @@
 #include <net/inet_common.h>
 #include <net/inet_ecn.h>
 
+#define MAX_SCTP_PORT_HASH_ENTRIES (64 * 1024)
+
 /* Global data structures. */
 struct sctp_globals sctp_globals __read_mostly;
 
@@ -1355,6 +1357,8 @@ static __init int sctp_init(void)
         unsigned long limit;
         int max_share;
         int order;
+        int num_entries;
+        int max_entry_order;
 
         sock_skb_cb_check_size(sizeof(struct sctp_ulpevent));
 
@@ -1407,14 +1411,24 @@ static __init int sctp_init(void)
 
         /* Size and allocate the association hash table.
          * The methodology is similar to that of the tcp hash tables.
+         * Though not identical.  Start by getting a goal size
          */
         if (totalram_pages >= (128 * 1024))
                 goal = totalram_pages >> (22 - PAGE_SHIFT);
         else
                 goal = totalram_pages >> (24 - PAGE_SHIFT);
 
-        for (order = 0; (1UL << order) < goal; order++)
-                ;
+        /* Then compute the page order for said goal */
+        order = get_order(goal);
+
+        /* Now compute the required page order for the maximum sized table we
+         * want to create
+         */
+        max_entry_order = get_order(MAX_SCTP_PORT_HASH_ENTRIES *
+                                    sizeof(struct sctp_bind_hashbucket));
+
+        /* Limit the page order by that maximum hash table size */
+        order = min(order, max_entry_order);
 
         /* Allocate and initialize the endpoint hash table.  */
         sctp_ep_hashsize = 64;
@@ -1430,20 +1444,35 @@ static __init int sctp_init(void)
                 INIT_HLIST_HEAD(&sctp_ep_hashtable[i].chain);
         }
 
-        /* Allocate and initialize the SCTP port hash table.  */
+        /* Allocate and initialize the SCTP port hash table.
+         * Note that order is initalized to start at the max sized
+         * table we want to support.  If we can't get that many pages
+         * reduce the order and try again
+         */
         do {
-                sctp_port_hashsize = (1UL << order) * PAGE_SIZE /
-                                        sizeof(struct sctp_bind_hashbucket);
-                if ((sctp_port_hashsize > (64 * 1024)) && order > 0)
-                        continue;
                 sctp_port_hashtable = (struct sctp_bind_hashbucket *)
                         __get_free_pages(GFP_KERNEL | __GFP_NOWARN, order);
         } while (!sctp_port_hashtable && --order > 0);
+
         if (!sctp_port_hashtable) {
                 pr_err("Failed bind hash alloc\n");
                 status = -ENOMEM;
                 goto err_bhash_alloc;
         }
+
+        /* Now compute the number of entries that will fit in the
+         * port hash space we allocated
+         */
+        num_entries = (1UL << order) * PAGE_SIZE /
+                      sizeof(struct sctp_bind_hashbucket);
+
+        /* And finish by rounding it down to the nearest power of two
+         * this wastes some memory of course, but its needed because
+         * the hash function operates based on the assumption that
+         * that the number of entries is a power of two
+         */
+        sctp_port_hashsize = rounddown_pow_of_two(num_entries);
+
         for (i = 0; i < sctp_port_hashsize; i++) {
                 spin_lock_init(&sctp_port_hashtable[i].lock);
                 INIT_HLIST_HEAD(&sctp_port_hashtable[i].chain);
@@ -1452,7 +1481,8 @@ static __init int sctp_init(void)
         if (sctp_transport_hashtable_init())
                 goto err_thash_alloc;
 
-        pr_info("Hash tables configured (bind %d)\n", sctp_port_hashsize);
+        pr_info("Hash tables configured (bind %d/%d)\n", sctp_port_hashsize,
+                num_entries);
 
         sctp_sysctl_register();