From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from cn.fujitsu.com ([222.73.24.84]:8878 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1757115Ab3G3Dje (ORCPT ); Mon, 29 Jul 2013 23:39:34 -0400 Message-ID: <51F735AE.2050902@cn.fujitsu.com> Date: Tue, 30 Jul 2013 11:40:30 +0800 From: Miao Xie Reply-To: miaox@cn.fujitsu.com MIME-Version: 1.0 To: Azat Khuzhin CC: linux-btrfs@vger.kernel.org, chris.mason@fusionio.com, open list Subject: Re: [PATCH] btrfs: use list_for_each_entry_safe() when delete items References: <1374919965-11690-1-git-send-email-a3at.mail@gmail.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On mon, 29 Jul 2013 11:48:32 +0400, Azat Khuzhin wrote: > On Sat, Jul 27, 2013 at 2:12 PM, Azat Khuzhin wrote: >> Replace list_for_each_entry() by list_for_each_entry_safe() in >> __btrfs_close_devices() >> >> There is another place that delete items lock_stripe_add(), but there we >> don't need safe version, because after deleting we exit from loop. >> >> Signed-off-by: Azat Khuzhin >> --- >> fs/btrfs/volumes.c | 4 ++-- >> 1 file changed, 2 insertions(+), 2 deletions(-) >> >> diff --git a/fs/btrfs/volumes.c b/fs/btrfs/volumes.c >> index 78b8717..1d1b595 100644 >> --- a/fs/btrfs/volumes.c >> +++ b/fs/btrfs/volumes.c >> @@ -616,13 +616,13 @@ static void free_device(struct rcu_head *head) >> >> static int __btrfs_close_devices(struct btrfs_fs_devices *fs_devices) >> { >> - struct btrfs_device *device; >> + struct btrfs_device *device, *next; >> >> if (--fs_devices->opened > 0) >> return 0; >> >> mutex_lock(&fs_devices->device_list_mutex); >> - list_for_each_entry(device, &fs_devices->devices, dev_list) { >> + list_for_each_entry_safe(device, next, &fs_devices->devices, dev_list) { >> struct btrfs_device *new_device; >> struct rcu_string *name; > > There is "kfree(device);" at the end of loop, maybe there must "goto > again;" after it? > (instead of this patch) Your fix is right, we needn't search from the head once again. The other fix way is: call_rcu(&device->rcu, free_device); + device = new_device; } but from the viewpoint of the readability, this way is not so good. Reviewed-by: Miao Xie > >> >> -- >> 1.7.10.4 >> > > >