linux-kernel - Re: [PATCH 02/47] block-rbd: Less function calls in rbd_header_from

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Date:   Tue, 13 Sep 2016 09:58:39 +0200
From:   Ilya Dryomov <idryomov@...il.com>
To:     SF Markus Elfring <elfring@...rs.sourceforge.net>
Cc:     Ceph Development <ceph-devel@...r.kernel.org>,
        Alex Elder <elder@...nel.org>, Sage Weil <sage@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>,
        kernel-janitors@...r.kernel.org,
        Julia Lawall <julia.lawall@...6.fr>
Subject: Re: [PATCH 02/47] block-rbd: Less function calls in
 rbd_header_from_disk() after error detection

On Mon, Sep 12, 2016 at 8:43 PM, SF Markus Elfring
<elfring@...rs.sourceforge.net> wrote:
> From: Markus Elfring <elfring@...rs.sourceforge.net>
> Date: Sun, 11 Sep 2016 13:18:57 +0200
>
> The functions "ceph_put_snap_context" and "kfree" were called in a few
> cases by the function "rbd_header_from_disk" during error handling
> even if the passed variables contained a null pointer.
>
> Adjust jump targets according to the Linux coding style convention.
>
> Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> ---
>  drivers/block/rbd.c | 10 ++++++----
>  1 file changed, 6 insertions(+), 4 deletions(-)
>
> diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
> index e406c27..f4212e1 100644
> --- a/drivers/block/rbd.c
> +++ b/drivers/block/rbd.c
> @@ -1001,7 +1001,7 @@ static int rbd_header_from_disk(struct rbd_device *rbd_dev,
>         snap_count = le32_to_cpu(ondisk->snap_count);
>         snapc = ceph_create_snap_context(snap_count, GFP_KERNEL);
>         if (!snapc)
> -               goto out_err;
> +               goto free_prefix;
>         snapc->seq = le64_to_cpu(ondisk->snap_seq);
>         if (snap_count) {
>                 struct rbd_image_snap_ondisk *snaps;
> @@ -1013,14 +1013,14 @@ static int rbd_header_from_disk(struct rbd_device *rbd_dev,
>                         goto out_2big;
>                 snap_names = kmalloc(snap_names_len, GFP_KERNEL);
>                 if (!snap_names)
> -                       goto out_err;
> +                       goto put_snap_context;
>
>                 /* ...as well as the array of their sizes. */
>                 snap_sizes = kmalloc_array(snap_count,
>                                            sizeof(*header->snap_sizes),
>                                            GFP_KERNEL);
>                 if (!snap_sizes)
> -                       goto out_err;
> +                       goto free_names;
>
>                 /*
>                  * Copy the names, and fill in each snapshot's id
> @@ -1066,10 +1066,12 @@ static int rbd_header_from_disk(struct rbd_device *rbd_dev,
>         return 0;
>  out_2big:
>         ret = -EIO;
> -out_err:
>         kfree(snap_sizes);
> + free_names:
>         kfree(snap_names);
> + put_snap_context:
>         ceph_put_snap_context(snapc);
> + free_prefix:
>         kfree(object_prefix);
>
>         return ret;
> --
> 2.10.0
>

Please don't send patches that restructure error handling gotos unless
you've spotted a bug.  These patches are easy to get wrong, especially
when done in bulk, and require careful review.

Some people fancy a single sink label approach, others like separate
labels for each cleanup action - as long as the code is working, it's
a matter of taste.

Thanks,

                Ilya