lkml.org 
[lkml]   [2012]   [Apr]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH v2] Btrfs, lockdep: get_restripe_target: use lockdep in BUG_ON
From
On Wed, Apr 4, 2012 at 10:04 PM, Bobby Powers <bobbypowers@gmail.com> wrote:
> spin_is_locked always returns 0 on non-SMP systems, which causes btrfs
> to fail the mount.  There is documentation pending as to why checking

I guess I should be explicit in stating that this is a regression, so
this patch or something else that addresses it should be pulled into
3.4.

> for spin_is_locked is a bad idea:
>
> https://lkml.org/lkml/2012/3/27/413
>
> The suggested lockdep_assert_held() is not appropriate in this case,
> as what get_restripe_target() is checking for is that either
> volume_mutex is held or balance_lock is held.  Luckily
> lockdep_assert_held() is a simple macro:
>
> WARN_ON(debug_locks && !lockdep_is_held(l))
>
> We can mimic the structure in get_restripe_target(), but we need to
> make sure lockdep_is_held() is defined for the !LOCKDEP case.
>
> CC: Ilya Dryomov <idryomov@gmail.com>
> CC: Chris Mason <chris.mason@oracle.com>
> CC: Andi Kleen <ak@linux.intel.com>
> CC: Jeff Mahoney <jeffm@suse.de>
> CC: Ingo Molnar <mingo@redhat.com>
> CC: linux-kernel@vger.kernel.org
> Signed-off-by: Bobby Powers <bobbypowers@gmail.com>
> ---
>  fs/btrfs/extent-tree.c  |    5 +++--
>  include/linux/lockdep.h |    1 +
>  2 files changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/fs/btrfs/extent-tree.c b/fs/btrfs/extent-tree.c
> index a844204..4d13eb1 100644
> --- a/fs/btrfs/extent-tree.c
> +++ b/fs/btrfs/extent-tree.c
> @@ -24,6 +24,7 @@
>  #include <linux/kthread.h>
>  #include <linux/slab.h>
>  #include <linux/ratelimit.h>
> +#include <linux/lockdep.h>
>  #include "compat.h"
>  #include "hash.h"
>  #include "ctree.h"
> @@ -3158,8 +3159,8 @@ static u64 get_restripe_target(struct btrfs_fs_info *fs_info, u64 flags)
>        struct btrfs_balance_control *bctl = fs_info->balance_ctl;
>        u64 target = 0;
>
> -       BUG_ON(!mutex_is_locked(&fs_info->volume_mutex) &&
> -              !spin_is_locked(&fs_info->balance_lock));
> +       BUG_ON(debug_locks && !lockdep_is_held(&fs_info->volume_mutex) &&
> +              !lockdep_is_held(&fs_info->balance_lock));
>
>        if (!bctl)
>                return 0;
> diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
> index d36619e..94c0edb 100644
> --- a/include/linux/lockdep.h
> +++ b/include/linux/lockdep.h
> @@ -392,6 +392,7 @@ struct lock_class_key { };
>
>  #define lockdep_depth(tsk)     (0)
>
> +#define lockdep_is_held(l)     (0)
>  #define lockdep_assert_held(l)                 do { } while (0)
>
>  #define lockdep_recursing(tsk)                 (0)
> --
> 1.7.10.rc3.3.g19a6c
>
--
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/

\
 
 \ /
  Last update: 2012-04-05 18:25    [W:0.204 / U:0.076 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site