Messages in this thread | | | Subject | Re: ERROR: modpost: "__delay" [drivers/net/mdio/mdio-cavium.ko] undefined! | From | Randy Dunlap <> | Date | Mon, 31 May 2021 08:12:21 -0700 |
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On 5/31/21 12:32 AM, Geert Uytterhoeven wrote: > CC David (original author, asked by driver location change) > > On Mon, May 31, 2021 at 9:29 AM Geert Uytterhoeven <geert@linux-m68k.org> wrote: >> >> On Mon, May 31, 2021 at 2:05 AM Randy Dunlap <rdunlap@infradead.org> wrote: >>> On 5/29/21 4:25 PM, kernel test robot wrote: >>>> First bad commit (maybe != root cause): >>>> >>>> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master >>>> head: df8c66c4cfb91f2372d138b9b714f6df6f506966 >>>> commit: a9770eac511ad82390b9f4a3c1728e078c387ac7 net: mdio: Move MDIO drivers into a new subdirectory >>>> date: 9 months ago >>>> config: sh-allmodconfig (attached as .config) >>>> compiler: sh4-linux-gcc (GCC) 9.3.0 >>>> 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://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=a9770eac511ad82390b9f4a3c1728e078c387ac7 >>>> git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git >>>> git fetch --no-tags linus master >>>> git checkout a9770eac511ad82390b9f4a3c1728e078c387ac7 >>>> # save the attached .config to linux build tree >>>> COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=sh >>>> >>>> If you fix the issue, kindly add following tag as appropriate >>>> Reported-by: kernel test robot <lkp@intel.com> >>>> >>>> All errors (new ones prefixed by >>, old ones prefixed by <<): >>>> >>>>>> ERROR: modpost: "__delay" [drivers/net/mdio/mdio-cavium.ko] undefined! >>> >>> Just a comment here. kernel test robot has reported this issue >>> 5 times in 2021 that I know of -- and I could have missed some. >>> >>> I see that Geert recently (June 2020) reverted the >>> EXPORT_SYMBOL(__delay) in arch/sh/lib/delay.c, with this comment: >>> >>> __delay() is an internal implementation detail on several architectures. >>> Drivers should not call __delay() directly, as it has non-standardized >>> semantics, or may not even exist. >>> Hence there is no need to export __delay() to modules. >>> >>> See also include/asm-generic/delay.h: >>> >>> /* Undefined functions to get compile-time errors */ >>> ... >>> extern void __delay(unsigned long loops); >>> >>> However, s/several architectures/all but one architecture: SH/. >>> All architectures except for SH provide either an exported function, >>> an inline function, or a macro for __delay(). Yeah, they probably >>> don't all do the same delay. >> >> Hence it must not be used by drivers, as it might give the false assumption >> of working everywhere. While drivers/net/mdio/mdio-cavium is >> platform-specific, code might be copied in a new driver, less restricted >> to a specific platform.
Geert, should all (15) of the other arch EXPORT_SYMBOL(__delay); exports be removed? (in theory? I'm not planning to remove them.)
-- ~Randy
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