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

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Message-ID: <CAL+tcoBDJty6o_-c4__P=BES_uP6emO3TcuUTrFCJ92j2wNWPg@mail.gmail.com>
Date: Wed, 11 Jun 2025 20:20:10 +0800
From: Jason Xing <kerneljasonxing@...il.com>
To: Masami Hiramatsu <mhiramat@...nel.org>
Cc: kernel test robot <lkp@...el.com>, axboe@...nel.dk, rostedt@...dmis.org, 
	mathieu.desnoyers@...icios.com, akpm@...ux-foundation.org, 
	oe-kbuild-all@...ts.linux.dev, linux-kernel@...r.kernel.org, 
	linux-block@...r.kernel.org, linux-trace-kernel@...r.kernel.org, 
	Jason Xing <kernelxing@...cent.com>, Yushan Zhou <katrinzhou@...cent.com>
Subject: Re: [PATCH v4 4/5] blktrace: use rbuf->stats.full as a drop indicator
 in relayfs

On Wed, Jun 11, 2025 at 4:08 PM Masami Hiramatsu <mhiramat@...nel.org> wrote:
>
> On Wed, 11 Jun 2025 13:15:40 +0800
> Jason Xing <kerneljasonxing@...il.com> wrote:
>
> > On Wed, Jun 11, 2025 at 9:42 AM kernel test robot <lkp@...el.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@...el.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.

Sure, thanks for the review.

> BTW, size_t should use %zu.
> Please check Documentation/core-api/printk-formats.rst

Thanks for the pointer :)

Thanks,
Jason
>
> 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@...nel.org>