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-rw-r--r--ipc/shm.c16
1 files changed, 13 insertions, 3 deletions
diff --git a/ipc/shm.c b/ipc/shm.c
index d20cc25..8cf1cf3 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -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;
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