Do 'shm_init_ns()' in an early pure_initcall

[pandora-kernel.git] / ipc / shm.c

diff --git a/ipc/shm.c b/ipc/shm.c
index 3f5b143..02ecf2c 100644 (file)
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -105,9 +105,16 @@ void shm_exit_ns(struct ipc_namespace *ns)
 }
 #endif
 
-void __init shm_init (void)
+static int __init ipc_ns_init(void)
 {
        shm_init_ns(&init_ipc_ns);
+       return 0;
+}
+
+pure_initcall(ipc_ns_init);
+
+void __init shm_init (void)
+{
        ipc_init_proc_interface("sysvipc/shm",
 #if BITS_PER_LONG <= 32
                                "       key      shmid perms       size  cpid  lpid nattch   uid   gid  cuid  cgid      atime      dtime      ctime        rss       swap\n",
@@ -131,6 +138,12 @@ static inline struct shmid_kernel *shm_lock(struct ipc_namespace *ns, int id)
        return container_of(ipcp, struct shmid_kernel, shm_perm);
 }
 
+static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp)
+{
+       rcu_read_lock();
+       spin_lock(&ipcp->shm_perm.lock);
+}
+
 static inline struct shmid_kernel *shm_lock_check(struct ipc_namespace *ns,
                                                int id)
 {
@@ -231,76 +244,80 @@ static void shm_close(struct vm_area_struct *vma)
        up_write(&shm_ids(ns).rw_mutex);
 }
 
+/* Called with ns->shm_ids(ns).rw_mutex locked */
 static int shm_try_destroy_current(int id, void *p, void *data)
 {
        struct ipc_namespace *ns = data;
-       struct shmid_kernel *shp = shm_lock(ns, id);
+       struct kern_ipc_perm *ipcp = p;
+       struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 
-       if (IS_ERR(shp))
+       if (shp->shm_creator != current)
                return 0;
 
-       if (shp->shm_cprid != task_tgid_vnr(current)) {
-               shm_unlock(shp);
+       /*
+        * Mark it as orphaned to destroy the segment when
+        * kernel.shm_rmid_forced is changed.
+        * It is noop if the following shm_may_destroy() returns true.
+        */
+       shp->shm_creator = NULL;
+
+       /*
+        * Don't even try to destroy it.  If shm_rmid_forced=0 and IPC_RMID
+        * is not set, it shouldn't be deleted here.
+        */
+       if (!ns->shm_rmid_forced)
                return 0;
-       }
 
-       if (shm_may_destroy(ns, shp))
+       if (shm_may_destroy(ns, shp)) {
+               shm_lock_by_ptr(shp);
                shm_destroy(ns, shp);
-       else
-               shm_unlock(shp);
+       }
        return 0;
 }
 
+/* Called with ns->shm_ids(ns).rw_mutex locked */
 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 {
        struct ipc_namespace *ns = data;
-       struct shmid_kernel *shp = shm_lock(ns, id);
-       struct task_struct *task;
-
-       if (IS_ERR(shp))
-               return 0;
+       struct kern_ipc_perm *ipcp = p;
+       struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
 
        /*
         * We want to destroy segments without users and with already
         * exit'ed originating process.
         *
-        * XXX: the originating process may exist in another pid namespace.
+        * As shp->* are changed under rw_mutex, it's safe to skip shp locking.
         */
-       task = find_task_by_vpid(shp->shm_cprid);
-       if (task != NULL) {
-               shm_unlock(shp);
+       if (shp->shm_creator != NULL)
                return 0;
-       }
 
-       if (shm_may_destroy(ns, shp))
+       if (shm_may_destroy(ns, shp)) {
+               shm_lock_by_ptr(shp);
                shm_destroy(ns, shp);
-       else
-               shm_unlock(shp);
+       }
        return 0;
 }
 
 void shm_destroy_orphaned(struct ipc_namespace *ns)
 {
        down_write(&shm_ids(ns).rw_mutex);
-       idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
+       if (shm_ids(ns).in_use)
+               idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_orphaned, ns);
        up_write(&shm_ids(ns).rw_mutex);
 }
 
 
 void exit_shm(struct task_struct *task)
 {
-       struct nsproxy *nsp = task->nsproxy;
-       struct ipc_namespace *ns;
+       struct ipc_namespace *ns = task->nsproxy->ipc_ns;
 
-       if (!nsp)
-               return;
-       ns = nsp->ipc_ns;
-       if (!ns || !ns->shm_rmid_forced)
+       if (shm_ids(ns).in_use == 0)
                return;
 
        /* Destroy all already created segments, but not mapped yet */
        down_write(&shm_ids(ns).rw_mutex);
-       idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
+       if (shm_ids(ns).in_use)
+               idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
        up_write(&shm_ids(ns).rw_mutex);
 }
 
@@ -494,6 +511,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
        shp->shm_segsz = size;
        shp->shm_nattch = 0;
        shp->shm_file = file;
+       shp->shm_creator = current;
        /*
         * shmid gets reported as "inode#" in /proc/pid/maps.
         * proc-ps tools use this. Changing this will break them.