path: root/ipc/util.h
diff options
authorDavidlohr Bueso <>2013-04-30 19:15:19 -0700
committerLinus Torvalds <>2013-05-01 08:12:57 -0700
commit4d2bff5eb86e8d7b4a20934cccb93bdeebed3558 (patch)
tree3667eec32ddcf8686335f64db553613c319f0625 /ipc/util.h
parent7bb4deff61bdab3338534841cb6d0508314a41d6 (diff)
ipc: introduce obtaining a lockless ipc object
Through ipc_lock() and therefore ipc_lock_check() we currently return the locked ipc object. This is not necessary for all situations and can, therefore, cause unnecessary ipc lock contention. Introduce analogous ipc_obtain_object() and ipc_obtain_object_check() functions that only lookup and return the ipc object. Both these functions must be called within the RCU read critical section. [ propagate the ipc_obtain_object() errno from ipc_lock()] Signed-off-by: Davidlohr Bueso <> Signed-off-by: Rik van Riel <> Reviewed-by: Chegu Vinod <> Acked-by: Michel Lespinasse <> Cc: Emmanuel Benisty <> Cc: Jason Low <> Cc: Peter Hurley <> Cc: Stanislav Kinsbursky <> Tested-by: Sedat Dilek <> Signed-off-by: Andrew Morton <> Signed-off-by: Linus Torvalds <>
Diffstat (limited to 'ipc/util.h')
1 files changed, 2 insertions, 0 deletions
diff --git a/ipc/util.h b/ipc/util.h
index ac1480a4efd1..bfc8d4ea6e46 100644
--- a/ipc/util.h
+++ b/ipc/util.h
@@ -123,6 +123,7 @@ void ipc_rcu_getref(void *ptr);
void ipc_rcu_putref(void *ptr);
struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
+struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id);
void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
@@ -168,6 +169,7 @@ static inline void ipc_unlock(struct kern_ipc_perm *perm)
struct kern_ipc_perm *ipc_lock_check(struct ipc_ids *ids, int id);
+struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
struct ipc_ops *ops, struct ipc_params *params);
void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,