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.

[[email protected]: propagate the ipc_obtain_object() errno from ipc_lock()]
Signed-off-by: Davidlohr Bueso <[email protected]>
Signed-off-by: Rik van Riel <[email protected]>
Reviewed-by: Chegu Vinod <[email protected]>
Acked-by: Michel Lespinasse <[email protected]>
Cc: Emmanuel Benisty <[email protected]>
Cc: Jason Low <[email protected]>
Cc: Peter Hurley <[email protected]>
Cc: Stanislav Kinsbursky <[email protected]>
Tested-by: Sedat Dilek <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

0 files changed, 0 insertions, 0 deletions