1 files changed, 39 insertions, 36 deletions

diff --git a/ipc/shm.c b/ipc/shm.c
index 89fc354156cb..7fc9f9f3a26b 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -178,6 +178,7 @@ static void shm_rcu_free(struct rcu_head *head)
 
 static inline void shm_rmid(struct ipc_namespace *ns, struct shmid_kernel *s)
 {
+        list_del(&s->shm_clist);
         ipc_rmid(&shm_ids(ns), &s->shm_perm);
 }
 
@@ -268,37 +269,6 @@ static void shm_close(struct vm_area_struct *vma)
 }
 
 /* Called with ns->shm_ids(ns).rwsem locked */
-static int shm_try_destroy_current(int id, void *p, void *data)
-{
-        struct ipc_namespace *ns = data;
-        struct kern_ipc_perm *ipcp = p;
-        struct shmid_kernel *shp = container_of(ipcp, struct shmid_kernel, shm_perm);
-
-        if (shp->shm_creator != current)
-                return 0;
-
-        /*
-         * 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)) {
-                shm_lock_by_ptr(shp);
-                shm_destroy(ns, shp);
-        }
-        return 0;
-}
-
-/* Called with ns->shm_ids(ns).rwsem locked */
 static int shm_try_destroy_orphaned(int id, void *p, void *data)
 {
         struct ipc_namespace *ns = data;
@@ -329,18 +299,50 @@ void shm_destroy_orphaned(struct ipc_namespace *ns)
         up_write(&shm_ids(ns).rwsem);
 }
 
-
+/* Locking assumes this will only be called with task == current */
 void exit_shm(struct task_struct *task)
 {
         struct ipc_namespace *ns = task->nsproxy->ipc_ns;
+        struct shmid_kernel *shp, *n;
 
-        if (shm_ids(ns).in_use == 0)
+        if (list_empty(&task->sysvshm.shm_clist))
                 return;
 
-        /* Destroy all already created segments, but not mapped yet */
+        /*
+         * If kernel.shm_rmid_forced is not set then only keep track of
+         * which shmids are orphaned, so that a later set of the sysctl
+         * can clean them up.
+         */
+        if (!ns->shm_rmid_forced) {
+                down_read(&shm_ids(ns).rwsem);
+                list_for_each_entry(shp, &task->sysvshm.shm_clist, shm_clist)
+                        shp->shm_creator = NULL;
+                /*
+                 * Only under read lock but we are only called on current
+                 * so no entry on the list will be shared.
+                 */
+                list_del(&task->sysvshm.shm_clist);
+                up_read(&shm_ids(ns).rwsem);
+                return;
+        }
+
+        /*
+         * Destroy all already created segments, that were not yet mapped,
+         * and mark any mapped as orphan to cover the sysctl toggling.
+         * Destroy is skipped if shm_may_destroy() returns false.
+         */
         down_write(&shm_ids(ns).rwsem);
-        if (shm_ids(ns).in_use)
-                idr_for_each(&shm_ids(ns).ipcs_idr, &shm_try_destroy_current, ns);
+        list_for_each_entry_safe(shp, n, &task->sysvshm.shm_clist, shm_clist) {
+                shp->shm_creator = NULL;
+
+                if (shm_may_destroy(ns, shp)) {
+                        shm_lock_by_ptr(shp);
+                        shm_destroy(ns, shp);
+                }
+        }
+
+        /* Remove the list head from any segments still attached. */
+        list_del(&task->sysvshm.shm_clist);
         up_write(&shm_ids(ns).rwsem);
 }
 
@@ -561,6 +563,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params)
         shp->shm_nattch = 0;
         shp->shm_file = file;
         shp->shm_creator = current;
+        list_add(&shp->shm_clist, &current->sysvshm.shm_clist);
 
         /*
          * shmid gets reported as "inode#" in /proc/pid/maps.