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Message-ID: <cb25d69c78e9bb754bd76701c9253f44@codeaurora.org>
Date: Wed, 03 Mar 2021 16:27:12 -0800
From: abhinavk@...eaurora.org
To: Dan Carpenter <dan.carpenter@...cle.com>
Cc: kbuild@...ts.01.org, lkp@...el.com, kbuild-all@...ts.01.org,
linux-kernel@...r.kernel.org, Rob Clark <robdclark@...omium.org>
Subject: Re: drivers/gpu/drm/msm/dp/dp_debug.c:218 dp_debug_init() warn:
passing zero to 'PTR_ERR'
Hi Dan
Thanks for reporting this, will submit a change to fix this.
Abhinav
On 2021-02-28 23:14, Dan Carpenter wrote:
> tree:
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
> master
> head: fe07bfda2fb9cdef8a4d4008a409bb02f35f1bd8
> commit: d11a93690df7e9a7e07c0784ecad019a627b1449 drm/msm/dp: add
> debugfs support to DP driver
> config: arm64-randconfig-m031-20210301 (attached as .config)
> compiler: aarch64-linux-gcc (GCC) 9.3.0
>
> If you fix the issue, kindly add following tag as appropriate
> Reported-by: kernel test robot <lkp@...el.com>
> Reported-by: Dan Carpenter <dan.carpenter@...cle.com>
>
> New smatch warnings:
> drivers/gpu/drm/msm/dp/dp_debug.c:218 dp_debug_init() warn: passing
> zero to 'PTR_ERR'
>
> Old smatch warnings:
> drivers/gpu/drm/msm/dp/dp_debug.c:227 dp_debug_init() warn: passing
> zero to 'PTR_ERR'
>
> vim +/PTR_ERR +218 drivers/gpu/drm/msm/dp/dp_debug.c
>
> d11a93690df7e9 Abhinav Kumar 2020-09-12 209 static int
> dp_debug_init(struct dp_debug *dp_debug)
> d11a93690df7e9 Abhinav Kumar 2020-09-12 210 {
> d11a93690df7e9 Abhinav Kumar 2020-09-12 211 int rc = 0;
> d11a93690df7e9 Abhinav Kumar 2020-09-12 212 struct dp_debug_private
> *debug = container_of(dp_debug,
> d11a93690df7e9 Abhinav Kumar 2020-09-12 213 struct
> dp_debug_private, dp_debug);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 214 struct dentry *dir,
> *file;
> d11a93690df7e9 Abhinav Kumar 2020-09-12 215
> d11a93690df7e9 Abhinav Kumar 2020-09-12 216 dir =
> debugfs_create_dir(DEBUG_NAME, NULL);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 217 if (IS_ERR_OR_NULL(dir))
> {
> d11a93690df7e9 Abhinav Kumar 2020-09-12 @218 rc = PTR_ERR(dir);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 219 DRM_ERROR("[%s]
> debugfs create dir failed, rc = %d\n",
> d11a93690df7e9 Abhinav Kumar 2020-09-12 220 DEBUG_NAME, rc);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 221 goto error;
>
> Debugfs function never return NULL, but actually debugfs functions
> aren't supposed to be checked in the normal case (the abnormal case is
> where you are trying to dereference "dir" and "file" within the driver
> itself, so it doesn't apply here).
>
> So then the function becomes a lot simpler, if it's written in the
> canonical way. This should probably be documented better in the
> Documentation/filesystems/debugfs.rst file... :/
>
> static void dp_debug_init(struct dp_debug *dp_debug)
> {
> struct dp_debug_private *debug = container_of(dp_debug,
> struct dp_debug_private, dp_debug);
>
> debug->root = debugfs_create_dir(DEBUG_NAME, NULL);
> debugfs_create_file("dp_debug", 0444, dir, debug, &dp_debug_fops);
> }
>
> d11a93690df7e9 Abhinav Kumar 2020-09-12 222 }
> d11a93690df7e9 Abhinav Kumar 2020-09-12 223
> d11a93690df7e9 Abhinav Kumar 2020-09-12 224 file =
> debugfs_create_file("dp_debug", 0444, dir,
> d11a93690df7e9 Abhinav Kumar 2020-09-12 225 debug,
> &dp_debug_fops);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 226 if
> (IS_ERR_OR_NULL(file)) {
> d11a93690df7e9 Abhinav Kumar 2020-09-12 227 rc = PTR_ERR(file);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 228 DRM_ERROR("[%s]
> debugfs create file failed, rc=%d\n",
> d11a93690df7e9 Abhinav Kumar 2020-09-12 229 DEBUG_NAME, rc);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 230 goto error_remove_dir;
> d11a93690df7e9 Abhinav Kumar 2020-09-12 231 }
> d11a93690df7e9 Abhinav Kumar 2020-09-12 232
> d11a93690df7e9 Abhinav Kumar 2020-09-12 233 debug->root = dir;
> d11a93690df7e9 Abhinav Kumar 2020-09-12 234 return rc;
> d11a93690df7e9 Abhinav Kumar 2020-09-12 235 error_remove_dir:
> d11a93690df7e9 Abhinav Kumar 2020-09-12 236 debugfs_remove(dir);
> d11a93690df7e9 Abhinav Kumar 2020-09-12 237 error:
> d11a93690df7e9 Abhinav Kumar 2020-09-12 238 return rc;
> d11a93690df7e9 Abhinav Kumar 2020-09-12 239 }
>
> ---
> 0-DAY CI Kernel Test Service, Intel Corporation
> https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
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