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/msg.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/msg.c')
-rw-r--r-- | ipc/msg.c | 19 |
1 files changed, 11 insertions, 8 deletions
diff --git a/ipc/msg.c b/ipc/msg.c index 104926dc72be..0ed7dae7d4e8 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -97,8 +97,8 @@ static inline void msg_rmid(struct ipc_namespace *ns, struct msg_queue *s) static void msg_rcu_free(struct rcu_head *head) { - struct ipc_rcu *p = container_of(head, struct ipc_rcu, rcu); - struct msg_queue *msq = ipc_rcu_to_struct(p); + struct kern_ipc_perm *p = container_of(head, struct kern_ipc_perm, rcu); + struct msg_queue *msq = container_of(p, struct msg_queue, q_perm); security_msg_queue_free(msq); ipc_rcu_free(head); @@ -118,7 +118,10 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) key_t key = params->key; int msgflg = params->flg; - msq = ipc_rcu_alloc(sizeof(*msq)); + BUILD_BUG_ON(offsetof(struct msg_queue, q_perm) != 0); + + msq = container_of(ipc_rcu_alloc(sizeof(*msq)), struct msg_queue, + q_perm); if (!msq) return -ENOMEM; @@ -128,7 +131,7 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) msq->q_perm.security = NULL; retval = security_msg_queue_alloc(msq); if (retval) { - ipc_rcu_putref(msq, ipc_rcu_free); + ipc_rcu_putref(&msq->q_perm, ipc_rcu_free); return retval; } @@ -144,7 +147,7 @@ static int newque(struct ipc_namespace *ns, struct ipc_params *params) /* ipc_addid() locks msq upon success. */ id = ipc_addid(&msg_ids(ns), &msq->q_perm, ns->msg_ctlmni); if (id < 0) { - ipc_rcu_putref(msq, msg_rcu_free); + ipc_rcu_putref(&msq->q_perm, msg_rcu_free); return id; } @@ -249,7 +252,7 @@ static void freeque(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp) free_msg(msg); } atomic_sub(msq->q_cbytes, &ns->msg_bytes); - ipc_rcu_putref(msq, msg_rcu_free); + ipc_rcu_putref(&msq->q_perm, msg_rcu_free); } /* @@ -688,7 +691,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, /* enqueue the sender and prepare to block */ ss_add(msq, &s, msgsz); - if (!ipc_rcu_getref(msq)) { + if (!ipc_rcu_getref(&msq->q_perm)) { err = -EIDRM; goto out_unlock0; } @@ -700,7 +703,7 @@ long do_msgsnd(int msqid, long mtype, void __user *mtext, rcu_read_lock(); ipc_lock_object(&msq->q_perm); - ipc_rcu_putref(msq, msg_rcu_free); + ipc_rcu_putref(&msq->q_perm, msg_rcu_free); /* raced with RMID? */ if (!ipc_valid_object(&msq->q_perm)) { err = -EIDRM; |