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author | Manfred Spraul <manfred@colorfullife.com> | 2017-07-12 14:34:41 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2017-07-12 16:26:01 -0700 |
commit | dba4cdd39e698d8dcdad0656825423052ac90ccd (patch) | |
tree | 908f984f4652a42f603aac8f2db4edd059d11256 /ipc/util.c | |
parent | 1a23395672658969a4035dcc518ea6cab835c579 (diff) | |
download | op-kernel-dev-dba4cdd39e698d8dcdad0656825423052ac90ccd.zip op-kernel-dev-dba4cdd39e698d8dcdad0656825423052ac90ccd.tar.gz |
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/util.c')
-rw-r--r-- | ipc/util.c | 35 |
1 files changed, 17 insertions, 18 deletions
@@ -418,46 +418,45 @@ void ipc_free(void *ptr) } /** - * ipc_rcu_alloc - allocate ipc and rcu space + * ipc_rcu_alloc - allocate ipc space * @size: size desired * - * Allocate memory for the rcu header structure + the object. - * Returns the pointer to the object or NULL upon failure. + * Allocate memory for an ipc object. + * The first member must be struct kern_ipc_perm. */ -void *ipc_rcu_alloc(int size) +struct kern_ipc_perm *ipc_rcu_alloc(int size) { /* * We prepend the allocation with the rcu struct */ - struct ipc_rcu *out = ipc_alloc(sizeof(struct ipc_rcu) + size); + struct kern_ipc_perm *out = ipc_alloc(size); if (unlikely(!out)) return NULL; + + memset(out, 0, size); atomic_set(&out->refcount, 1); - return out + 1; + return out; } -int ipc_rcu_getref(void *ptr) +int ipc_rcu_getref(struct kern_ipc_perm *ptr) { - struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; - - return atomic_inc_not_zero(&p->refcount); + return atomic_inc_not_zero(&ptr->refcount); } -void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head)) +void ipc_rcu_putref(struct kern_ipc_perm *ptr, + void (*func)(struct rcu_head *head)) { - struct ipc_rcu *p = ((struct ipc_rcu *)ptr) - 1; - - if (!atomic_dec_and_test(&p->refcount)) + if (!atomic_dec_and_test(&ptr->refcount)) return; - call_rcu(&p->rcu, func); + call_rcu(&ptr->rcu, func); } -void ipc_rcu_free(struct rcu_head *head) +void ipc_rcu_free(struct rcu_head *h) { - struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); + struct kern_ipc_perm *ptr = container_of(h, struct kern_ipc_perm, rcu); - kvfree(p); + kvfree(ptr); } /** |