Re: [PATCH v4 4/5] blktrace: use rbuf->stats.full as a drop indicator in relayfs

[Masami Hiramatsu (Google) <mhiramat@kernel.org>]

On Wed, 11 Jun 2025 13:15:40 +0800
Jason Xing <kerneljasonxing@gmail.com> wrote:

> On Wed, Jun 11, 2025 at 9:42 AM kernel test robot <lkp@intel.com> wrote:
> >
> > Hi Jason,
> >
> > kernel test robot noticed the following build warnings:
> >
> > [auto build test WARNING on axboe-block/for-next]
> > [also build test WARNING on drm-i915/for-linux-next drm-i915/for-linux-next-fixes akpm-mm/mm-everything linus/master v6.16-rc1 next-20250610]
> > [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/Jason-Xing/relayfs-abolish-prev_padding/20250610-085150
> > base:   https://git.kernel.org/pub/scm/linux/kernel/git/axboe/linux-block.git for-next
> > patch link:    https://lore.kernel.org/r/20250610004844.66688-5-kerneljasonxing%40gmail.com
> > patch subject: [PATCH v4 4/5] blktrace: use rbuf->stats.full as a drop indicator in relayfs
> > config: arc-randconfig-001-20250610
> > compiler: arc-linux-gcc (GCC) 12.4.0
> > reproduce (this is a W=1 build):
> >
> > 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@intel.com>
> > | Closes: https://lore.kernel.org/oe-kbuild-all/202506102340.uo7QDaVk-lkp@intel.com/
> >
> > All warnings (new ones prefixed by >>):
> >
> >    kernel/trace/blktrace.c: In function 'blk_dropped_read':
> > >> kernel/trace/blktrace.c:421:39: warning: format '%lu' expects argument of type 'long unsigned int', but argument 4 has type 'size_t' {aka 'unsigned int'} [-Wformat=]
> >      421 |         snprintf(buf, sizeof(buf), "%lu\n", dropped);
> >          |                                     ~~^     ~~~~~~~
> >          |                                       |     |
> >          |                                       |     size_t {aka unsigned int}
> >          |                                       long unsigned int
> >          |                                     %u
> 
> Well, I suppose I will fix it in the re-spin after receiving more
> comments so that I don't need to quickly respond to this minor issue.

Please update the patch and send series with my reviewed-by on 1/5.
BTW, size_t should use %zu.
Please check Documentation/core-api/printk-formats.rst

Thank you,

> 
> Thanks,
> Jason
> 
> >
> >
> > vim +421 kernel/trace/blktrace.c
> >
> >    413
> >    414  static ssize_t blk_dropped_read(struct file *filp, char __user *buffer,
> >    415                                  size_t count, loff_t *ppos)
> >    416  {
> >    417          struct blk_trace *bt = filp->private_data;
> >    418          size_t dropped = relay_stats(bt->rchan, RELAY_STATS_BUF_FULL);
> >    419          char buf[16];
> >    420
> >  > 421          snprintf(buf, sizeof(buf), "%lu\n", dropped);
> >    422
> >    423          return simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
> >    424  }
> >    425
> >
> > --
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests/wiki


-- 
Masami Hiramatsu (Google) <mhiramat@kernel.org>