Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757881Ab3CTURh (ORCPT ); Wed, 20 Mar 2013 16:17:37 -0400 Received: from shelob.surriel.com ([74.92.59.67]:38944 "EHLO shelob.surriel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756281Ab3CTUPm (ORCPT ); Wed, 20 Mar 2013 16:15:42 -0400 X-Greylist: delayed 1187 seconds by postgrey-1.27 at vger.kernel.org; Wed, 20 Mar 2013 16:15:42 EDT From: Rik van Riel To: torvalds@linux-foundation.org Cc: davidlohr.bueso@hp.com, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, hhuang@redhat.com, jason.low2@hp.com, walken@google.com, lwoodman@redhat.com, chegu_vinod@hp.com, Rik van Riel , Rik van Riel Subject: [PATCH 5/7] ipc,sem: open code and rename sem_lock Date: Wed, 20 Mar 2013 15:55:35 -0400 Message-Id: <1363809337-29718-6-git-send-email-riel@surriel.com> X-Mailer: git-send-email 1.7.7.6 In-Reply-To: <1363809337-29718-1-git-send-email-riel@surriel.com> References: <1363809337-29718-1-git-send-email-riel@surriel.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1999 Lines: 65 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 ff3d4ff..d25f9b6 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; + + spin_lock(&ipcp->lock); + + /* ipc_rmid() may have already freed the ID while sem_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: + spin_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) @@ -1562,7 +1577,7 @@ 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. -- 1.7.7.6 -- 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/