From mboxrd@z Thu Jan 1 00:00:00 1970 From: "yukuai (C)" Subject: Re: [PATCH -next v2 2/2] blk-throttle: fix io hung due to configuration updates Date: Thu, 19 May 2022 15:06:38 +0800 Message-ID: <20bc6370-999b-ed3c-4b8f-19b2cdba5965@huawei.com> References: <20220518072751.1188163-3-yukuai3@huawei.com> <202205182347.tMOOqyfL-lkp@intel.com> <84fe296e-6e56-3ca9-73a8-357beb675c6e@huawei.com> <3d6878f4-1902-633d-0af2-276831364a4f@huawei.com> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Return-path: In-Reply-To: List-ID: Content-Type: text/plain; charset="utf-8"; format="flowed" To: Geert Uytterhoeven Cc: kernel test robot , Tejun Heo , Jens Axboe , Ming Lei , kbuild-all-hn68Rpc1hR1g9hUCZPvPmw@public.gmane.org, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, linux-block , Linux Kernel Mailing List , yi.zhang-hv44wF8Li93QT0dZR+AlfA@public.gmane.org 在 2022/05/19 15:01, Geert Uytterhoeven 写道: > Hi Yukuai, > > On Thu, May 19, 2022 at 5:25 AM yukuai (C) wrote: >> 在 2022/05/19 10:11, yukuai (C) 写道: >>> 在 2022/05/18 23:52, kernel test robot 写道: >>>> Thank you for the patch! Yet something to improve: >>>> >>>> [auto build test ERROR on next-20220517] >>>> >>>> url: >>>> https://github.com/intel-lab-lkp/linux/commits/Yu-Kuai/bugfix-for-blk-throttle/20220518-151713 >>>> >>>> base: 47c1c54d1bcd0a69a56b49473bc20f17b70e5242 >>>> config: m68k-allyesconfig >>>> (https://download.01.org/0day-ci/archive/20220518/202205182347.tMOOqyfL-lkp-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org/config) >>>> >>>> compiler: m68k-linux-gcc (GCC) 11.3.0 >>>> reproduce (this is a W=1 build): >>>> wget >>>> https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross >>>> -O ~/bin/make.cross >>>> chmod +x ~/bin/make.cross >>>> # >>>> https://github.com/intel-lab-lkp/linux/commit/f8345dbaf4ed491742aab29834aff66b4930c087 >>>> >>>> git remote add linux-review >>>> https://github.com/intel-lab-lkp/linux >>>> git fetch --no-tags linux-review >>>> Yu-Kuai/bugfix-for-blk-throttle/20220518-151713 >>>> git checkout f8345dbaf4ed491742aab29834aff66b4930c087 >>>> # save the config file >>>> mkdir build_dir && cp config build_dir/.config >>>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 >>>> make.cross W=1 O=build_dir ARCH=m68k SHELL=/bin/bash >>>> >>>> If you fix the issue, kindly add following tag as appropriate >>>> Reported-by: kernel test robot >>>> >>>> All errors (new ones prefixed by >>): >>>> >>>> m68k-linux-ld: block/blk-throttle.o: in function `tg_conf_updated': >>>>>> blk-throttle.c:(.text+0x25bc): undefined reference to `__udivdi3' >>>>>> m68k-linux-ld: blk-throttle.c:(.text+0x2626): undefined reference to >>>>>> `__udivdi3' >>> Hi, >>> >>> I'm confused here, the only place that I can relate to this: >>> >>> return dispatched * new_limit / old_limit; >>> >>> However, I don't understand yet why this is problematic... >>>> `.exit.text' referenced in section `.data' of >>>> sound/soc/codecs/tlv320adc3xxx.o: defined in discarded section >>>> `.exit.text' of sound/soc/codecs/tlv320adc3xxx.o >> >> + static u64 throtl_update_bytes_disp(u64 dispatched, u64 new_limit, >> + u64 old_limit) >> + { >> + if (new_limit == old_limit) >> + return dispatched; >> + >> + if (new_limit == U64_MAX) >> + return 0; >> + >> + return dispatched * new_limit / old_limit; >> >> I understand it now. I'm doing (u64 / u64), I should use div64_u64 > > Better, use mul_u64_u64_div_u64(), as "dispatched * new_limit" > may overflow? Hi, It's right that it can overflow, I'll handle such case in next version. > >> + } >> + >> + static u32 throtl_update_io_disp(u32 dispatched, u32 new_limit, u32 old_limit) >> + { >> + if (new_limit == old_limit) >> + return dispatched; >> + >> + if (new_limit == UINT_MAX) >> + return 0; >> + >> + return dispatched * new_limit / old_limit; > > This is the same as above, but now operating on u32s instead of u64s. > Likewise, can the multiplication overflow? same as above. Thanks, Kuai > >> + } > > Gr{oetje,eeting}s, > > Geert > > -- > Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert-Td1EMuHUCqxL1ZNQvxDV9g@public.gmane.org > > In personal conversations with technical people, I call myself a hacker. But > when I'm talking to journalists I just say "programmer" or something like that. > -- Linus Torvalds > . >