From: Chris Mason <chris.mason@oracle.com>
To: Tsutomu Itoh <t-itoh@jp.fujitsu.com>
Cc: David Sterba <dsterba@suse.cz>,
linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 05/12] btrfs: remove useless mutex lock/unlock sequences
Date: Mon, 25 Apr 2011 08:12:59 -0400 [thread overview]
Message-ID: <1303733509-sup-4508@think> (raw)
In-Reply-To: <4DB513F6.6040503@jp.fujitsu.com>
Excerpts from Tsutomu Itoh's message of 2011-04-25 02:25:58 -0400:
> (2011/04/22 18:41), David Sterba wrote:
> > Signed-off-by: David Sterba <dsterba@suse.cz>
> > ---
> > fs/btrfs/extent-tree.c | 6 ------
> > 1 files changed, 0 insertions(+), 6 deletions(-)
> >
> > diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> > index 31f33ba..c97ceab 100644
> > --- a/fs/btrfs/extent-tree.c
> > +++ b/fs/btrfs/extent-tree.c
> > @@ -756,8 +756,6 @@ again:
> >
> > btrfs_release_path(root->fs_info->extent_root, path);
> >
> > - mutex_lock(&head->mutex);
> > - mutex_unlock(&head->mutex);
> > btrfs_put_delayed_ref(&head->node);
> > goto again;
>
> This code tests whether the mutex_lock can be acquired, and when the
> mutex_lock can be taken, it try again.
> So I think that it is not a meaningless code.
Correct, this code is waiting for the current lock holder to finish.
It's not exactly pretty but it needs to stay.
-chris
next prev parent reply other threads:[~2011-04-25 12:12 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-04-22 9:41 [PATCH 00/12] Cleanups, cruft removal David Sterba
2011-04-22 9:41 ` [PATCH 01/12] btrfs: rename variables clashing with global function names David Sterba
2011-04-22 9:41 ` [PATCH 02/12] btrfs: remove nested duplicate variable declarations David Sterba
2011-04-22 9:41 ` [PATCH 03/12] btrfs: fix dereference before check David Sterba
2011-04-22 9:41 ` [PATCH 04/12] btrfs: unify checking of IS_ERR and null David Sterba
2011-04-22 9:41 ` [PATCH 05/12] btrfs: remove useless mutex lock/unlock sequences David Sterba
2011-04-25 6:25 ` Tsutomu Itoh
2011-04-25 12:12 ` Chris Mason [this message]
2011-04-29 16:34 ` David Sterba
2011-05-02 13:49 ` [PATCH] btrfs: Document a mutex lock/unlock sequence David Sterba
2011-04-22 9:41 ` [PATCH 06/12] btrfs: make functions static when possible David Sterba
2011-04-22 9:42 ` [PATCH 07/12] btrfs: drop unused argument from extent_io_tree_init David Sterba
2011-04-22 9:42 ` [PATCH 08/12] btrfs: drop unused parameter from extent_map_tree_init David Sterba
2011-04-22 9:42 ` [PATCH 09/12] btrfs: drop gfp parameter from alloc_extent_map David Sterba
2011-04-22 9:42 ` [PATCH 10/12] btrfs: drop gfp parameter from find_extent_buffer David Sterba
2011-04-22 9:43 ` [PATCH 11/12] btrfs: drop gfp parameter from alloc_extent_buffer David Sterba
2011-04-22 9:43 ` [PATCH 12/12] btrfs: drop unused parameter from btrfs_release_path David Sterba
2011-05-02 14:01 ` [PATCH 00/12] Cleanups, cruft removal David Sterba
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