ipc: merge ipc_rcu and kern_ipc_perm
ipc has two management structures that exist for every id:
- struct kern_ipc_perm, it contains e.g. the permissions.
- struct ipc_rcu, it contains the rcu head for rcu handling and the
refcount.
The patch merges both structures.
As a bonus, we may save one cacheline, because both structures are
cacheline aligned. In addition, it reduces the number of casts, instead
most codepaths can use container_of.
To simplify code, the ipc_rcu_alloc initializes the allocation to 0.
[[email protected]: really include the memset() into ipc_alloc_rcu()]
Link: http://lkml.kernel.org/r/[email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Manfred Spraul <[email protected]>
Cc: Davidlohr Bueso <[email protected]>
Cc: Kees Cook <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
diff --git a/include/linux/ipc.h b/include/linux/ipc.h
index 71fd92d..5591f055 100644
--- a/include/linux/ipc.h
+++ b/include/linux/ipc.h
@@ -20,6 +20,9 @@ struct kern_ipc_perm {
umode_t mode;
unsigned long seq;
void *security;
+
+ struct rcu_head rcu;
+ atomic_t refcount;
} ____cacheline_aligned_in_smp;
#endif /* _LINUX_IPC_H */
