diff options
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 16 |
1 files changed, 13 insertions, 3 deletions
@@ -63,8 +63,6 @@ static struct ipc_ids init_shm_ids; ((struct shmid_kernel*)ipc_lock(&shm_ids(ns),id)) #define shm_unlock(shp) \ ipc_unlock(&(shp)->shm_perm) -#define shm_get(ns, id) \ - ((struct shmid_kernel*)ipc_get(&shm_ids(ns),id)) #define shm_buildid(ns, id, seq) \ ipc_buildid(&shm_ids(ns), id, seq) @@ -563,7 +561,19 @@ static void shm_get_stat(struct ipc_namespace *ns, unsigned long *rss, struct shmid_kernel *shp; struct inode *inode; - shp = shm_get(ns, next_id); + /* + * idr_find() is called via shm_get(), so with shm_ids.mutex + * locked. Since ipc_addid() is also called with + * shm_ids.mutex down, there is no need to add read barriers + * here to gurantee the writes in ipc_addid() are seen in + * order here (for Alpha). + * However idr_find() itself does not necessary require + * ipc_ids.mutex down. So if idr_find() is used by other + * places without ipc_ids.mutex down, then it needs read + * read memory barriers as ipc_lock() does. + */ + + shp = idr_find(&shm_ids(ns).ipcs_idr, next_id); if (shp == NULL) continue; |
