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ipc: merge ipc_rcu and kern_ipc_perm

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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>
This commit is contained in:
Manfred Spraul
2017-07-12 14:34:41 -07:00
committed by Linus Torvalds
parent 1a23395672
commit dba4cdd39e
6 changed files with 66 additions and 61 deletions
Download Patch File Download Diff File Expand all files Collapse all files

35
ipc/util.c
View File

@@ -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);
}
/**