Re: [PATCH 6/6] drm: zynqmp_dp: Add debugfs interface for compliance testing
From: Yujie Liu
Date: Wed Mar 20 2024 - 02:10:16 EST
Hi Sean,
On Mon, Mar 18, 2024 at 03:05:57PM -0400, Sean Anderson wrote:
> On 3/18/24 13:50, Laurent Pinchart wrote:
> > On Mon, Mar 18, 2024 at 11:06:40AM -0400, Sean Anderson wrote:
> >> On 3/16/24 06:14, kernel test robot wrote:
> >> > Hi Sean,
> >> >
> >> > kernel test robot noticed the following build warnings:
> >> >
> >> > [auto build test WARNING on v6.8]
> >> > [cannot apply to drm-misc/drm-misc-next linus/master next-20240315]
> >> > [If your patch is applied to the wrong git tree, kindly drop us a note.
> >> > And when submitting patch, we suggest to use '--base' as documented in
> >> > https://git-scm.com/docs/git-format-patch#_base_tree_information]
> >> >
> >> > url: https://github.com/intel-lab-lkp/linux/commits/Sean-Anderson/drm-zynqmp_dp-Downgrade-log-level-for-aux-retries-message/20240316-071208
> >> > base: v6.8
> >> > patch link: https://lore.kernel.org/r/20240315230916.1759060-7-sean.anderson%40linux.dev
> >> > patch subject: [PATCH 6/6] drm: zynqmp_dp: Add debugfs interface for compliance testing
> >> > config: microblaze-allmodconfig (https://download.01.org/0day-ci/archive/20240316/202403161704.ACHJdSJG-lkp@xxxxxxxxx/config)
> >> > compiler: microblaze-linux-gcc (GCC) 13.2.0
> >> > reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20240316/202403161704.ACHJdSJG-lkp@xxxxxxxxx/reproduce)
[...]
> >> >
> >> > If you fix the issue in a separate patch/commit (i.e. not just a new version of
> >> > the same patch/commit), kindly add following tags
> >> > | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> >> > | Closes: https://lore.kernel.org/oe-kbuild-all/202403161704.ACHJdSJG-lkp@xxxxxxxxx/
> >> >
> >> > All warnings (new ones prefixed by >>):
> >> >
> >> > drivers/gpu/drm/xlnx/zynqmp_dp.c: In function 'zynqmp_dp_bridge_debugfs_init':
> >> >>> drivers/gpu/drm/xlnx/zynqmp_dp.c:2168:31: warning: 'sprintf' may write a terminating nul past the end of the destination [-Wformat-overflow=]
> >> > 2168 | sprintf(name, fmt, i);
> >> > | ^~~
> >> > drivers/gpu/drm/xlnx/zynqmp_dp.c:2168:17: note: 'sprintf' output between 18 and 20 bytes into a destination of size 19
> >> > 2168 | sprintf(name, fmt, i);
> >> > | ^~~~~~~~~~~~~~~~~~~~~
> >>
> >> Not a bug, as i will be at most 4, which uses 1 digit.
> >
> > The compiler can't know that. Please fix this, there's a zero warning
> > policy.
>
> I cannot reproduce this with GCC 13.2.0. So given that this is not a bug and I can't reproduce
> it, I don't see how I can verify any fix.
There is a "reproduce" link in the bot's report. We followed the steps
in that link and found that the warning could be reproduced. Please
notice that this is a "W=1" warning. BTW, we also tested the v2 patch
and the warning has been fixed there. Just for your information.
$ cd linux
$ git checkout v6.8
HEAD is now at e8f897f4afef0 Linux 6.8
$ b4 am https://lore.kernel.org/r/20240315230916.1759060-7-sean.anderson@xxxxxxxxx
$ git am ./20240315_sean_anderson_drm_zynqmp_dp_misc_patches_and_debugfs_support.mbx
Applying: drm: zynqmp_dp: Downgrade log level for aux retries message
Applying: drm: zynqmp_dp: Adjust training values per-lane
Applying: drm: zynqmp_dp: Add locking
Applying: drm: zynqmp_dp: Split off several helper functions
Applying: drm: zynqmp_dp: Optionally ignore DPCD errors
Applying: drm: zynqmp_dp: Add debugfs interface for compliance testing
$ wget https://download.01.org/0day-ci/archive/20240316/202403161704.ACHJdSJG-lkp@xxxxxxxxx/config
$ mkdir build_dir
$ cp config build_dir/.config
$ git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
$ COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=microblaze olddefconfig
$ COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=microblaze drivers/gpu/drm/xlnx/zynqmp_dp.o
..
CC [M] drivers/gpu/drm/xlnx/zynqmp_dp.o
./drivers/gpu/drm/xlnx/zynqmp_dp.c: In function 'zynqmp_dp_bridge_debugfs_init':
./drivers/gpu/drm/xlnx/zynqmp_dp.c:2168:31: warning: 'sprintf' may write a terminating nul past the end of the destination [-Wformat-overflow=]
2168 | sprintf(name, fmt, i);
| ^~~
./drivers/gpu/drm/xlnx/zynqmp_dp.c:2168:17: note: 'sprintf' output between 18 and 20 bytes into a destination of size 19
2168 | sprintf(name, fmt, i);
| ^~~~~~~~~~~~~~~~~~~~~
Best Regards,
Yujie
>
> --Sean
>
> >> > vim +/sprintf +2168 drivers/gpu/drm/xlnx/zynqmp_dp.c
> >> >
> >> > 2136
> >> > 2137 DEFINE_DEBUGFS_ATTRIBUTE(fops_zynqmp_dp_rate, zynqmp_dp_rate_get,
> >> > 2138 zynqmp_dp_rate_set, "%llu\n");
> >> > 2139
> >> > 2140 static void zynqmp_dp_bridge_debugfs_init(struct drm_bridge *bridge,
> >> > 2141 struct dentry *root)
> >> > 2142 {
> >> > 2143 struct zynqmp_dp *dp = bridge_to_dp(bridge);
> >> > 2144 struct dentry *test;
> >> > 2145 int i;
> >> > 2146
> >> > 2147 dp->test.bw_code = DP_LINK_BW_5_4;
> >> > 2148 dp->test.link_cnt = dp->num_lanes;
> >> > 2149
> >> > 2150 test = debugfs_create_dir("test", root);
> >> > 2151 #define CREATE_FILE(name) \
> >> > 2152 debugfs_create_file(#name, 0600, test, dp, &fops_zynqmp_dp_##name)
> >> > 2153 CREATE_FILE(pattern);
> >> > 2154 CREATE_FILE(enhanced);
> >> > 2155 CREATE_FILE(downspread);
> >> > 2156 CREATE_FILE(active);
> >> > 2157 CREATE_FILE(custom);
> >> > 2158 CREATE_FILE(rate);
> >> > 2159 CREATE_FILE(lanes);
> >> > 2160
> >> > 2161 for (i = 0; i < dp->num_lanes; i++) {
> >> > 2162 static const char fmt[] = "lane%d_preemphasis";
> >> > 2163 char name[sizeof(fmt)];
> >> > 2164
> >> > 2165 dp->debugfs_train_set[i].dp = dp;
> >> > 2166 dp->debugfs_train_set[i].lane = i;
> >> > 2167
> >> >> 2168 sprintf(name, fmt, i);
> >> > 2169 debugfs_create_file(name, 0600, test,
> >> > 2170 &dp->debugfs_train_set[i],
> >> > 2171 &fops_zynqmp_dp_preemphasis);
> >> > 2172
> >> > 2173 sprintf(name, "lane%d_swing", i);
> >> > 2174 debugfs_create_file(name, 0600, test,
> >> > 2175 &dp->debugfs_train_set[i],
> >> > 2176 &fops_zynqmp_dp_swing);
> >> > 2177 }
> >> > 2178 }
> >> > 2179
> >
>
>