Merge branch 'sysctl' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc-2.6

* 'sysctl' of git://git.kernel.org/pub/scm/linux/kernel/git/ak/linux-misc-2.6:
  SYSCTL: Add a mutex to the page_alloc zone order sysctl
  SYSCTL: Print binary sysctl warnings (nearly) only once

2 files changed, 37 insertions, 5 deletions

diff --git a/kernel/sysctl_binary.c b/kernel/sysctl_binary.c
index 112533d5fc08..8f5d16e0707a 100644
--- a/kernel/sysctl_binary.c
+++ b/kernel/sysctl_binary.c
@@ -1417,6 +1417,35 @@ static void deprecated_sysctl_warning(const int *name, int nlen)
         return;
 }
 
+#define WARN_ONCE_HASH_BITS 8
+#define WARN_ONCE_HASH_SIZE (1<<WARN_ONCE_HASH_BITS)
+
+static DECLARE_BITMAP(warn_once_bitmap, WARN_ONCE_HASH_SIZE);
+
+#define FNV32_OFFSET 2166136261U
+#define FNV32_PRIME 0x01000193
+
+/*
+ * Print each legacy sysctl (approximately) only once.
+ * To avoid making the tables non-const use a external
+ * hash-table instead.
+ * Worst case hash collision: 6, but very rarely.
+ * NOTE! We don't use the SMP-safe bit tests. We simply
+ * don't care enough.
+ */
+static void warn_on_bintable(const int *name, int nlen)
+{
+        int i;
+        u32 hash = FNV32_OFFSET;
+
+        for (i = 0; i < nlen; i++)
+                hash = (hash ^ name[i]) * FNV32_PRIME;
+        hash %= WARN_ONCE_HASH_SIZE;
+        if (__test_and_set_bit(hash, warn_once_bitmap))
+                return;
+        deprecated_sysctl_warning(name, nlen);
+}
+
 static ssize_t do_sysctl(int __user *args_name, int nlen,
         void __user *oldval, size_t oldlen, void __user *newval, size_t newlen)
 {
@@ -1431,7 +1460,7 @@ static ssize_t do_sysctl(int __user *args_name, int nlen,
                 if (get_user(name[i], args_name + i))
                         return -EFAULT;
 
-        deprecated_sysctl_warning(name, nlen);
+        warn_on_bintable(name, nlen);
 
         return binary_sysctl(name, nlen, oldval, oldlen, newval, newlen);
 }
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index d79b92580561..4e9f5cc5fb59 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2402,13 +2402,14 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
 {
         char saved_string[NUMA_ZONELIST_ORDER_LEN];
         int ret;
+        static DEFINE_MUTEX(zl_order_mutex);
 
+        mutex_lock(&zl_order_mutex);
         if (write)
-                strncpy(saved_string, (char*)table->data,
-                        NUMA_ZONELIST_ORDER_LEN);
+                strcpy(saved_string, (char*)table->data);
         ret = proc_dostring(table, write, buffer, length, ppos);
         if (ret)
-                return ret;
+                goto out;
         if (write) {
                 int oldval = user_zonelist_order;
                 if (__parse_numa_zonelist_order((char*)table->data)) {
@@ -2421,7 +2422,9 @@ int numa_zonelist_order_handler(ctl_table *table, int write,
                 } else if (oldval != user_zonelist_order)
                         build_all_zonelists();
         }
-        return 0;
+out:
+        mutex_unlock(&zl_order_mutex);
+        return ret;
 }