diff options
| author | Manfred Spraul | 2017-07-12 14:34:41 -0700 |
|---|---|---|
| committer | Linus Torvalds | 2017-07-12 16:26:01 -0700 |
| commit | dba4cdd39e698d8dcdad0656825423052ac90ccd (patch) | |
| tree | 908f984f4652a42f603aac8f2db4edd059d11256 /ipc/shm.c | |
| parent | 1a23395672658969a4035dcc518ea6cab835c579 (diff) | |
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.
[manfred@colorfullife.com: really include the memset() into ipc_alloc_rcu()]
Link: http://lkml.kernel.org/r/564f8612-0601-b267-514f-a9f650ec9b32@colorfullife.com
Link: http://lkml.kernel.org/r/20170525185107.12869-3-manfred@colorfullife.com
Signed-off-by: Manfred Spraul <manfred@colorfullife.com>
Cc: Davidlohr Bueso <dave@stgolabs.net>
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/shm.c')
| -rw-r--r-- | ipc/shm.c | 18 |
1 files changed, 11 insertions, 7 deletions
diff --git a/ipc/shm.c b/ipc/shm.c index f45c7959b264..5ef6d31a52c5 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -174,9 +174,10 @@ static inline void shm_lock_by_ptr(struct shmid_kernel *ipcp) static void shm_rcu_free(struct rcu_head *head) { - struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); - struct shmid_kernel *shp = ipc_rcu_to_struct(p); - + struct kern_ipc_perm *ptr = container_of(head, struct kern_ipc_perm, + rcu); + struct shmid_kernel *shp = container_of(ptr, struct shmid_kernel, + shm_perm); security_shm_free(shp); ipc_rcu_free(head); } @@ -241,7 +242,7 @@ static void shm_destroy(struct ipc_namespace *ns, struct shmid_kernel *shp) user_shm_unlock(i_size_read(file_inode(shm_file)), shp->mlock_user); fput(shm_file); - ipc_rcu_putref(shp, shm_rcu_free); + ipc_rcu_putref(&shp->shm_perm, shm_rcu_free); } /* @@ -542,7 +543,10 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) ns->shm_tot + numpages > ns->shm_ctlall) return -ENOSPC; - shp = ipc_rcu_alloc(sizeof(*shp)); + BUILD_BUG_ON(offsetof(struct shmid_kernel, shm_perm) != 0); + + shp = container_of(ipc_rcu_alloc(sizeof(*shp)), struct shmid_kernel, + shm_perm); if (!shp) return -ENOMEM; @@ -553,7 +557,7 @@ static int newseg(struct ipc_namespace *ns, struct ipc_params *params) shp->shm_perm.security = NULL; error = security_shm_alloc(shp); if (error) { - ipc_rcu_putref(shp, ipc_rcu_free); + ipc_rcu_putref(&shp->shm_perm, ipc_rcu_free); return error; } @@ -624,7 +628,7 @@ no_id: user_shm_unlock(size, shp->mlock_user); fput(file); no_file: - ipc_rcu_putref(shp, shm_rcu_free); + ipc_rcu_putref(&shp->shm_perm, shm_rcu_free); return error; } |