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-...@intel.com/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-...@intel.com/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 <l...@intel.com>
> >> > | Closes: 
> >> > https://lore.kernel.org/oe-kbuild-all/202403161704.achjdsjg-...@intel.com/
> >> > 
> >> > 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.ander...@linux.dev
$ 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-...@intel.com/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   
> > 
> 
> 

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