Re: [PATCH 3/3] btrfs: refactor btrfs_device->name updates

[Pranith Kumar]

On Sun, Nov 30, 2014 at 3:26 AM, Omar Sandoval <osandov@xxxxxxxxxxx> wrote:
> The rcu_string API introduced some new sparse errors but also revealed existing
> ones. First of all, the name in struct btrfs_device should be annotated as
> __rcu to prevent unsafe reads. Additionally, updates should go through
> rcu_dereference_protected to make it clear what's going on. This introduces
> some helper functions that factor out this functionality.
>
> Signed-off-by: Omar Sandoval <osandov@xxxxxxxxxxx>
> diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
> index 6e04f27..2298a70 100644
> --- a/fs/btrfs/volumes.h
> +++ b/fs/btrfs/volumes.h
> @@ -54,7 +54,7 @@ struct btrfs_device {
>
>         struct btrfs_root *dev_root;
>
> -       struct rcu_string *name;
> +       struct rcu_string __rcu *name;
>
>         u64 generation;
>

Since rcu_strings are rcu specific, why not annotate the char pointer
in 'struct rcu_string' with __rcu annotation? That should catch all
error-prone users of rcu_string.

-- 
Pranith
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