Fedora kernel-2.6.17-1.2142_FC4 patched with stable patch-2.6.17.4-vs2.0.2-rc26.diff

[linux-2.6.git] / kernel / user.c

diff --git a/kernel/user.c b/kernel/user.c
index 023d8c0..bcbd0b3 100644 (file)
--- a/kernel/user.c
+++ b/kernel/user.c
@@ -13,6 +13,7 @@
 #include <linux/slab.h>
 #include <linux/bitops.h>
 #include <linux/key.h>
+#include <linux/interrupt.h>
 
 /*
  * UID task count cache, to get fast user lookup in "alloc_uid"
@@ -27,6 +28,16 @@
 
 static kmem_cache_t *uid_cachep;
 static struct list_head uidhash_table[UIDHASH_SZ];
+
+/*
+ * The uidhash_lock is mostly taken from process context, but it is
+ * occasionally also taken from softirq/tasklet context, when
+ * task-structs get RCU-freed. Hence all locking must be softirq-safe.
+ * But free_uid() is also called with local interrupts disabled, and running
+ * local_bh_enable() with local interrupts disabled is an error - we'll run
+ * softirq callbacks, and they can unconditionally enable interrupts, and
+ * the caller of free_uid() didn't expect that..
+ */
 static DEFINE_SPINLOCK(uidhash_lock);
 
 struct user_struct root_user = {
@@ -82,21 +93,30 @@ static inline struct user_struct *uid_hash_find(xid_t xid, uid_t uid, struct lis
 struct user_struct *find_user(xid_t xid, uid_t uid)
 {
        struct user_struct *ret;
+       unsigned long flags;
 
-       spin_lock(&uidhash_lock);
+       spin_lock_irqsave(&uidhash_lock, flags);
        ret = uid_hash_find(xid, uid, uidhashentry(xid, uid));
-       spin_unlock(&uidhash_lock);
+       spin_unlock_irqrestore(&uidhash_lock, flags);
        return ret;
 }
 
 void free_uid(struct user_struct *up)
 {
-       if (up && atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
+       unsigned long flags;
+
+       if (!up)
+               return;
+
+       local_irq_save(flags);
+       if (atomic_dec_and_lock(&up->__count, &uidhash_lock)) {
                uid_hash_remove(up);
+               spin_unlock_irqrestore(&uidhash_lock, flags);
                key_put(up->uid_keyring);
                key_put(up->session_keyring);
                kmem_cache_free(uid_cachep, up);
-               spin_unlock(&uidhash_lock);
+       } else {
+               local_irq_restore(flags);
        }
 }
 
@@ -105,9 +125,9 @@ struct user_struct * alloc_uid(xid_t xid, uid_t uid)
        struct list_head *hashent = uidhashentry(xid, uid);
        struct user_struct *up;
 
-       spin_lock(&uidhash_lock);
+       spin_lock_irq(&uidhash_lock);
        up = uid_hash_find(xid, uid, hashent);
-       spin_unlock(&uidhash_lock);
+       spin_unlock_irq(&uidhash_lock);
 
        if (!up) {
                struct user_struct *new;
@@ -121,6 +141,10 @@ struct user_struct * alloc_uid(xid_t xid, uid_t uid)
                atomic_set(&new->processes, 0);
                atomic_set(&new->files, 0);
                atomic_set(&new->sigpending, 0);
+#ifdef CONFIG_INOTIFY
+               atomic_set(&new->inotify_watches, 0);
+               atomic_set(&new->inotify_devs, 0);
+#endif
 
                new->mq_bytes = 0;
                new->locked_shm = 0;
@@ -134,7 +158,7 @@ struct user_struct * alloc_uid(xid_t xid, uid_t uid)
                 * Before adding this, check whether we raced
                 * on adding the same user already..
                 */
-               spin_lock(&uidhash_lock);
+               spin_lock_irq(&uidhash_lock);
                up = uid_hash_find(xid, uid, hashent);
                if (up) {
                        key_put(new->uid_keyring);
@@ -144,7 +168,7 @@ struct user_struct * alloc_uid(xid_t xid, uid_t uid)
                        uid_hash_insert(new, hashent);
                        up = new;
                }
-               spin_unlock(&uidhash_lock);
+               spin_unlock_irq(&uidhash_lock);
 
        }
        return up;
@@ -180,9 +204,9 @@ static int __init uid_cache_init(void)
                INIT_LIST_HEAD(uidhash_table + n);
 
        /* Insert the root user immediately (init already runs as root) */
-       spin_lock(&uidhash_lock);
+       spin_lock_irq(&uidhash_lock);
        uid_hash_insert(&root_user, uidhashentry(0,0));
-       spin_unlock(&uidhash_lock);
+       spin_unlock_irq(&uidhash_lock);
 
        return 0;
 }