From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758688AbXIYTzZ (ORCPT ); Tue, 25 Sep 2007 15:55:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755266AbXIYTzN (ORCPT ); Tue, 25 Sep 2007 15:55:13 -0400 Received: from mx2.netapp.com ([216.240.18.37]:10705 "EHLO mx2.netapp.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755095AbXIYTzL (ORCPT ); Tue, 25 Sep 2007 15:55:11 -0400 X-IronPort-AV: E=Sophos;i="4.20,297,1186383600"; d="scan'208";a="107787355" Subject: NLM: Fix a circular lock dependency in lockd From: Trond Myklebust To: Linus Torvalds , stable@vger.kernel.org Cc: linux-kernel@vger.kernel.org, nfs@lists.sourceforge.net Content-Type: text/plain Content-Transfer-Encoding: 7bit Organization: Network Appliance Inc Date: Tue, 25 Sep 2007 15:55:03 -0400 Message-Id: <1190750103.7330.32.camel@heimdal.trondhjem.org> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 X-OriginalArrivalTime: 25 Sep 2007 19:55:05.0070 (UTC) FILETIME=[F788A0E0:01C7FFAD] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org The problem is that the garbage collector for the 'host' structures nlm_gc_hosts(), holds nlm_host_mutex while calling down to nlmsvc_mark_resources, which, eventually takes the file->f_mutex. We cannot therefore call nlmsvc_lookup_host() from within nlmsvc_create_block, since the caller will already hold file->f_mutex, so the attempt to grab nlm_host_mutex may deadlock. Fix the problem by calling nlmsvc_lookup_host() outside the file->f_mutex. Signed-off-by: Trond Myklebust --- fs/lockd/svclock.c | 29 ++++++++++++++++++----------- 1 files changed, 18 insertions(+), 11 deletions(-) diff --git a/fs/lockd/svclock.c b/fs/lockd/svclock.c index a21e4bc..d098c7a 100644 --- a/fs/lockd/svclock.c +++ b/fs/lockd/svclock.c @@ -171,19 +171,14 @@ found: * GRANTED_RES message by cookie, without having to rely on the client's IP * address. --okir */ -static inline struct nlm_block * -nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_file *file, - struct nlm_lock *lock, struct nlm_cookie *cookie) +static struct nlm_block * +nlmsvc_create_block(struct svc_rqst *rqstp, struct nlm_host *host, + struct nlm_file *file, struct nlm_lock *lock, + struct nlm_cookie *cookie) { struct nlm_block *block; - struct nlm_host *host; struct nlm_rqst *call = NULL; - /* Create host handle for callback */ - host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len); - if (host == NULL) - return NULL; - call = nlm_alloc_call(host); if (call == NULL) return NULL; @@ -366,6 +361,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, struct nlm_lock *lock, int wait, struct nlm_cookie *cookie) { struct nlm_block *block = NULL; + struct nlm_host *host; int error; __be32 ret; @@ -377,6 +373,10 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, (long long)lock->fl.fl_end, wait); + /* Create host handle for callback */ + host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len); + if (host == NULL) + return nlm_lck_denied_nolocks; /* Lock file against concurrent access */ mutex_lock(&file->f_mutex); @@ -385,7 +385,8 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, */ block = nlmsvc_lookup_block(file, lock); if (block == NULL) { - block = nlmsvc_create_block(rqstp, file, lock, cookie); + block = nlmsvc_create_block(rqstp, nlm_get_host(host), file, + lock, cookie); ret = nlm_lck_denied_nolocks; if (block == NULL) goto out; @@ -449,6 +450,7 @@ nlmsvc_lock(struct svc_rqst *rqstp, struct nlm_file *file, out: mutex_unlock(&file->f_mutex); nlmsvc_release_block(block); + nlm_release_host(host); dprintk("lockd: nlmsvc_lock returned %u\n", ret); return ret; } @@ -477,10 +479,15 @@ nlmsvc_testlock(struct svc_rqst *rqstp, struct nlm_file *file, if (block == NULL) { struct file_lock *conf = kzalloc(sizeof(*conf), GFP_KERNEL); + struct nlm_host *host; if (conf == NULL) return nlm_granted; - block = nlmsvc_create_block(rqstp, file, lock, cookie); + /* Create host handle for callback */ + host = nlmsvc_lookup_host(rqstp, lock->caller, lock->len); + if (host == NULL) + return nlm_lck_denied_nolocks; + block = nlmsvc_create_block(rqstp, host, file, lock, cookie); if (block == NULL) { kfree(conf); return nlm_granted;