Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6

[linux.git] / ipc / shm.c

diff --git a/ipc/shm.c b/ipc/shm.c
index a413ddf74daca26b2d22e1f81882cb07097d1ce8..b0eb3757ab895d07970bec60b55f9bd895f7bd8a 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -96,14 +96,14 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp);
 static int sysvipc_shm_proc_show(struct seq_file *s, void *it);
 #endif
 
-int shm_init_ns(struct ipc_namespace *ns)
+void shm_init_ns(struct ipc_namespace *ns)
 {
        ns->shm_ctlmax = SHMMAX;
        ns->shm_ctlall = SHMALL;
        ns->shm_ctlmni = SHMMNI;
        ns->shm_rmid_forced = 0;
        ns->shm_tot = 0;
-       return ipc_init_ids(&shm_ids(ns));
+       ipc_init_ids(&shm_ids(ns));
 }
 
 /*
@@ -136,9 +136,8 @@ void shm_exit_ns(struct ipc_namespace *ns)
 
 static int __init ipc_ns_init(void)
 {
-       const int err = shm_init_ns(&init_ipc_ns);
-       WARN(err, "ipc: sysv shm_init_ns failed: %d\n", err);
-       return err;
+       shm_init_ns(&init_ipc_ns);
+       return 0;
 }
 
 pure_initcall(ipc_ns_init);
@@ -180,16 +179,33 @@ static inline struct shmid_kernel *shm_obtain_object_check(struct ipc_namespace
  */
 static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
 {
-       struct kern_ipc_perm *ipcp = ipc_lock(&shm_ids(ns), id);
+       struct kern_ipc_perm *ipcp;
 
+       rcu_read_lock();
+       ipcp = ipc_obtain_object_idr(&shm_ids(ns), id);
+       if (IS_ERR(ipcp))
+               goto err;
+
+       ipc_lock_object(ipcp);
+       /*
+        * ipc_rmid() may have already freed the ID while ipc_lock_object()
+        * was spinning: here verify that the structure is still valid.
+        * Upon races with RMID, return -EIDRM, thus indicating that
+        * the ID points to a removed identifier.
+        */
+       if (ipc_valid_object(ipcp)) {
+               /* return a locked ipc object upon success */
+               return container_of(ipcp, struct shmid_kernel, shm_perm);
+       }
+
+       ipc_unlock_object(ipcp);
+err:
+       rcu_read_unlock();
        /*
         * Callers of shm_lock() must validate the status of the returned ipc
-        * object pointer (as returned by ipc_lock()), and error out as
-        * appropriate.
+        * object pointer and error out as appropriate.
         */
-       if (IS_ERR(ipcp))
-               return (void *)ipcp;
-       return container_of(ipcp, struct shmid_kernel, shm_perm);
+       return (void *)ipcp;
 }
 
 static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
@@ -932,7 +948,7 @@ static int shmctl_ipc_info(struct ipc_namespace *ns,
                shminfo->shmall = ns->shm_ctlall;
                shminfo->shmmin = SHMMIN;
                down_read(&shm_ids(ns).rwsem);
-               err = ipc_get_maxid(&shm_ids(ns));
+               err = ipc_get_maxidx(&shm_ids(ns));
                up_read(&shm_ids(ns).rwsem);
                if (err < 0)
                        err = 0;
@@ -952,7 +968,7 @@ static int shmctl_shm_info(struct ipc_namespace *ns,
                shm_info->shm_tot = ns->shm_tot;
                shm_info->swap_attempts = 0;
                shm_info->swap_successes = 0;
-               err = ipc_get_maxid(&shm_ids(ns));
+               err = ipc_get_maxidx(&shm_ids(ns));
                up_read(&shm_ids(ns).rwsem);
                if (err < 0)
                        err = 0;