Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756606Ab3CFWPv (ORCPT ); Wed, 6 Mar 2013 17:15:51 -0500 Received: from mx1.redhat.com ([209.132.183.28]:53984 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753905Ab3CFWPu (ORCPT ); Wed, 6 Mar 2013 17:15:50 -0500 Date: Wed, 6 Mar 2013 17:14:43 -0500 From: Rik van Riel To: Davidlohr Bueso Cc: Linus Torvalds , Emmanuel Benisty , "Vinod, Chegu" , "Low, Jason" , Peter Zijlstra , "H. Peter Anvin" , Andrew Morton , aquini@redhat.com, Michel Lespinasse , Ingo Molnar , Larry Woodman , Linux Kernel Mailing List , Steven Rostedt , Thomas Gleixner Subject: [PATCH v2 6/4] ipc: open code and rename sem_lock Message-ID: <20130306171443.6a1ee9d6@cuia.bos.redhat.com> In-Reply-To: <1362476149.2225.50.camel@buesod1.americas.hpqcorp.net> References: <1362476149.2225.50.camel@buesod1.americas.hpqcorp.net> Organization: Red Hat, Inc Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1991 Lines: 63 Rename sem_lock to sem_obtain_lock, so we can introduce a sem_lock function later that only locks the sem_array and does nothing else. Open code the locking from ipc_lock in sem_obtain_lock, so we can introduce finer grained locking for the sem_array in the next patch. Signed-off-by: Rik van Riel --- ipc/sem.c | 23 +++++++++++++++++++---- 1 files changed, 19 insertions(+), 4 deletions(-) diff --git a/ipc/sem.c b/ipc/sem.c index efb49e7..d92ba32 100644 --- a/ipc/sem.c +++ b/ipc/sem.c @@ -194,14 +194,29 @@ void __init sem_init (void) * sem_lock_(check_) routines are called in the paths where the rw_mutex * is not held. */ -static inline struct sem_array *sem_lock(struct ipc_namespace *ns, int id) +static inline struct sem_array *sem_obtain_lock(struct ipc_namespace *ns, int id) { - struct kern_ipc_perm *ipcp = ipc_lock(&sem_ids(ns), id); + struct kern_ipc_perm *ipcp; + rcu_read_lock(); + ipcp = ipc_obtain_object(&sem_ids(ns), id); if (IS_ERR(ipcp)) - return (struct sem_array *)ipcp; + goto err1; + + write_lock(&ipcp->lock); + + /* ipc_rmid() may have already freed the ID while write_lock + * was spinning: verify that the structure is still valid + */ + if (ipcp->deleted) + goto err0; return container_of(ipcp, struct sem_array, sem_perm); +err0: + write_unlock(&ipcp->lock); +err1: + rcu_read_unlock(); + return ERR_PTR(-EINVAL); } static inline struct sem_array *sem_obtain_object(struct ipc_namespace *ns, int id) @@ -1558,7 +1573,7 @@ SYSCALL_DEFINE4(semtimedop, int, semid, struct sembuf __user *, tsops, goto out_free; } - sma = sem_lock(ns, semid); + sma = sem_obtain_lock(ns, semid); /* * Wait until it's guaranteed that no wakeup_sem_queue_do() is ongoing. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/