From dba4cdd39e698d8dcdad0656825423052ac90ccd Mon Sep 17 00:00:00 2001 From: Manfred Spraul Date: Wed, 12 Jul 2017 14:34:41 -0700 Subject: 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 Cc: Davidlohr Bueso Cc: Kees Cook Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- ipc/util.c | 35 +++++++++++++++++------------------ 1 file changed, 17 insertions(+), 18 deletions(-) (limited to 'ipc/util.c') diff --git a/ipc/util.c b/ipc/util.c index caec7b1bfaa3..5d1ff1035efe 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -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); } /** -- cgit v1.2.3-59-g8ed1b