Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754724Ab3EPBJj (ORCPT ); Wed, 15 May 2013 21:09:39 -0400 Received: from g1t0027.austin.hp.com ([15.216.28.34]:34842 "EHLO g1t0027.austin.hp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754153Ab3EPBIQ (ORCPT ); Wed, 15 May 2013 21:08:16 -0400 From: Davidlohr Bueso To: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org, riel@redhat.com, linux-kernel@vger.kernel.org, Davidlohr Bueso Subject: [PATCH 08/11] ipc,msg: make msgctl_nolock lockless Date: Wed, 15 May 2013 18:08:07 -0700 Message-Id: <1368666490-29055-9-git-send-email-davidlohr.bueso@hp.com> X-Mailer: git-send-email 1.7.11.7 In-Reply-To: <1368666490-29055-1-git-send-email-davidlohr.bueso@hp.com> References: <1368666490-29055-1-git-send-email-davidlohr.bueso@hp.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2262 Lines: 84 While the INFO cmd doesn't take the ipc lock, the STAT commands do acquire it unnecessarily. We can do the permissions and security checks only holding the rcu lock. This function now mimics semctl_nolock(). Signed-off-by: Davidlohr Bueso --- ipc/msg.c | 27 +++++++++++++++++---------- 1 file changed, 17 insertions(+), 10 deletions(-) diff --git a/ipc/msg.c b/ipc/msg.c index 9ff295b..2d89b00 100644 --- a/ipc/msg.c +++ b/ipc/msg.c @@ -547,17 +547,25 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, if (!buf) return -EFAULT; + memset(&tbuf, 0, sizeof(tbuf)); + + rcu_read_lock(); if (cmd == MSG_STAT) { - msq = msg_lock(ns, msqid); - if (IS_ERR(msq)) - return PTR_ERR(msq); + msq = msq_obtain_object(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_unlock; + } success_return = msq->q_perm.id; } else { - msq = msg_lock_check(ns, msqid); - if (IS_ERR(msq)) - return PTR_ERR(msq); + msq = msq_obtain_object_check(ns, msqid); + if (IS_ERR(msq)) { + err = PTR_ERR(msq); + goto out_unlock; + } success_return = 0; } + err = -EACCES; if (ipcperms(ns, &msq->q_perm, S_IRUGO)) goto out_unlock; @@ -566,8 +574,6 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, if (err) goto out_unlock; - memset(&tbuf, 0, sizeof(tbuf)); - kernel_to_ipc64_perm(&msq->q_perm, &tbuf.msg_perm); tbuf.msg_stime = msq->q_stime; tbuf.msg_rtime = msq->q_rtime; @@ -577,7 +583,8 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, tbuf.msg_qbytes = msq->q_qbytes; tbuf.msg_lspid = msq->q_lspid; tbuf.msg_lrpid = msq->q_lrpid; - msg_unlock(msq); + rcu_read_unlock(); + if (copy_msqid_to_user(buf, &tbuf, version)) return -EFAULT; return success_return; @@ -589,7 +596,7 @@ static int msgctl_nolock(struct ipc_namespace *ns, int msqid, return err; out_unlock: - msg_unlock(msq); + rcu_read_unlock(); return err; } -- 1.7.11.7 -- 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/