sctp: Fix port hash table size computation

[pandora-kernel.git] / net / sctp / protocol.c

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index de35e01..149deae 100644 (file)
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -67,6 +67,8 @@
 #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;
 DEFINE_SNMP_STAT(struct sctp_mib, sctp_statistics) __read_mostly;
@@ -1206,6 +1208,8 @@ SCTP_STATIC __init int sctp_init(void)
        unsigned long limit;
        int max_share;
        int order;
+       int num_entries;
+       int max_entry_order;
 
        /* SCTP_DEBUG sanity check. */
        if (!sctp_sanity_check())
@@ -1316,14 +1320,24 @@ SCTP_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);
 
        do {
                sctp_assoc_hashsize = (1UL << order) * PAGE_SIZE /
@@ -1357,27 +1371,42 @@ SCTP_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_ATOMIC|__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);
        }
 
-       pr_info("Hash tables configured (established %d bind %d)\n",
-               sctp_assoc_hashsize, sctp_port_hashsize);
+       pr_info("Hash tables configured (established %d bind %d/%d)\n",
+               sctp_assoc_hashsize, sctp_port_hashsize, num_entries);
 
        /* Disable ADDIP by default. */
        sctp_addip_enable = 0;