From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx150.postini.com [74.125.245.150]) by kanga.kvack.org (Postfix) with SMTP id 1B6616B003D for ; Tue, 18 Jun 2013 21:19:01 -0400 (EDT) From: Davidlohr Bueso Subject: [PATCH 08/11] ipc,shm: shorten critical region for shmat Date: Tue, 18 Jun 2013 18:18:33 -0700 Message-Id: <1371604716-3439-9-git-send-email-davidlohr.bueso@hp.com> In-Reply-To: <1371604716-3439-1-git-send-email-davidlohr.bueso@hp.com> References: <1371604716-3439-1-git-send-email-davidlohr.bueso@hp.com> Sender: owner-linux-mm@kvack.org List-ID: To: akpm@linux-foundation.org, riel@redhat.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Cc: Davidlohr Bueso Similar to other system calls, acquire the kern_ipc_perm lock after doing the initial permission and security checks. Signed-off-by: Davidlohr Bueso --- ipc/shm.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/ipc/shm.c b/ipc/shm.c index d1b3ebf..2fe6170 100644 --- a/ipc/shm.c +++ b/ipc/shm.c @@ -19,6 +19,9 @@ * namespaces support * OpenVZ, SWsoft Inc. * Pavel Emelianov + * + * Better ipc lock (kern_ipc_perm.lock) handling + * Davidlohr Bueso , June 2013. */ #include @@ -1086,7 +1089,8 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, * additional creator id... */ ns = current->nsproxy->ipc_ns; - shp = shm_lock_check(ns, shmid); + rcu_read_lock(); + shp = shm_obtain_object_check(ns, shmid); if (IS_ERR(shp)) { err = PTR_ERR(shp); goto out; @@ -1100,11 +1104,13 @@ long do_shmat(int shmid, char __user *shmaddr, int shmflg, ulong *raddr, if (err) goto out_unlock; + ipc_lock_object(&shp->shm_perm); path = shp->shm_file->f_path; path_get(&path); shp->shm_nattch++; size = i_size_read(path.dentry->d_inode); - shm_unlock(shp); + ipc_unlock_object(&shp->shm_perm); + rcu_read_unlock(); err = -ENOMEM; sfd = kzalloc(sizeof(*sfd), GFP_KERNEL); @@ -1175,7 +1181,7 @@ out_nattch: return err; out_unlock: - shm_unlock(shp); + rcu_read_unlock(); out: return err; } -- 1.7.11.7 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org