From: Dan Carpenter <dan.carpenter@oracle.com>
To: Colin King <colin.king@canonical.com>
Cc: "David Airlie" <airlied@linux.ie>,
kernel-janitors@vger.kernel.org, linux-kernel@vger.kernel.org,
dri-devel@lists.freedesktop.org,
"Christian König" <christian.koenig@amd.com>
Subject: Re: [PATCH][next] drm/mm/selftests: fix unsigned comparison with less than zero
Date: Thu, 18 Jun 2020 10:39:56 +0000 [thread overview]
Message-ID: <20200618103956.GQ4151@kadam> (raw)
In-Reply-To: <20200617155959.231740-1-colin.king@canonical.com>
On Wed, Jun 17, 2020 at 04:59:59PM +0100, Colin King wrote:
> From: Colin Ian King <colin.king@canonical.com>
>
> Function get_insert_time can return error values that are cast
> to a u64. The checks of insert_time1 and insert_time2 check for
> the errors but because they are u64 variables the check for less
> than zero can never be true. Fix this by casting the value to s64
> to allow of the negative error check to succeed.
>
> Addresses-Coverity: ("Unsigned compared against 0, no effect")
> Fixes: 6e60d5ded06b ("drm/mm: add ig_frag selftest")
> Signed-off-by: Colin Ian King <colin.king@canonical.com>
> ---
> drivers/gpu/drm/selftests/test-drm_mm.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/selftests/test-drm_mm.c b/drivers/gpu/drm/selftests/test-drm_mm.c
> index 3846b0f5bae3..671a152a6df2 100644
> --- a/drivers/gpu/drm/selftests/test-drm_mm.c
> +++ b/drivers/gpu/drm/selftests/test-drm_mm.c
> @@ -1124,12 +1124,12 @@ static int igt_frag(void *ignored)
>
> insert_time1 = get_insert_time(&mm, insert_size,
> nodes + insert_size, mode);
> - if (insert_time1 < 0)
> + if ((s64)insert_time1 < 0)
> goto err;
The error codes in this function seem pretty messed up.
Speaking of error codes, what the heck is going on with
prepare_igt_frag().
1037 static int prepare_igt_frag(struct drm_mm *mm,
1038 struct drm_mm_node *nodes,
1039 unsigned int num_insert,
1040 const struct insert_mode *mode)
1041 {
1042 unsigned int size = 4096;
1043 unsigned int i;
1044 u64 ret = -EINVAL;
^^^^^^^^^^^^^^^^^^
Why is it u64?
1045
1046 for (i = 0; i < num_insert; i++) {
1047 if (!expect_insert(mm, &nodes[i], size, 0, i,
1048 mode) != 0) {
1049 pr_err("%s insert failed\n", mode->name);
1050 goto out;
^^^^^^^^
One of the common bugs with do nothing gotos is that we forget to set
the error code. If we did a direct "return -EINVAL;" here, then there
would be no ambiguity.
1051 }
1052 }
1053
1054 /* introduce fragmentation by freeing every other node */
1055 for (i = 0; i < num_insert; i++) {
1056 if (i % 2 = 0)
1057 drm_mm_remove_node(&nodes[i]);
1058 }
1059
1060 out:
1061 return ret;
1062
1063 }
regards,
dan carpenter
next prev parent reply other threads:[~2020-06-18 10:39 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-06-17 15:59 [PATCH][next] drm/mm/selftests: fix unsigned comparison with less than zero Colin King
2020-06-18 10:39 ` Dan Carpenter [this message]
2020-06-21 21:38 ` Nirmoy
2020-06-21 15:33 ` Christian König
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20200618103956.GQ4151@kadam \
--to=dan.carpenter@oracle.com \
--cc=airlied@linux.ie \
--cc=christian.koenig@amd.com \
--cc=colin.king@canonical.com \
--cc=dri-devel@lists.freedesktop.org \
--cc=kernel-janitors@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).