On Wed, May 15, 2019 at 8:34 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > On Wed, May 15, 2019 at 05:57:50PM +0900, Masahiro Yamada wrote: > > On Wed, May 15, 2019 at 5:14 PM Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> wrote: > > > > > > On Wed, May 15, 2019 at 10:08:12AM +0200, Arnd Bergmann wrote: > > > > On Wed, May 15, 2019 at 9:39 AM Masahiro Yamada > > > > <yamada.masahiro@xxxxxxxxxxxxx> wrote: > > > > > > > > > > In the recent build test of linux-next, Stephen saw a build error > > > > > caused by a broken .tmp_versions/*.mod file: > > > > > > > > > > https://lkml.org/lkml/2019/5/13/991 > > > > > > > > > > drivers/net/phy/asix.ko and drivers/net/usb/asix.ko have the same > > > > > basename, and there is a race in generating .tmp_versions/asix.mod > > > > > > > > > > Kbuild has not checked this before, and it occasionally shows up with > > > > > obscure error message when this kind of race occurs. > > > > > > > > > > It is not trivial to catch this potential issue by eyes. > > > > > > > > > > Hence, this script. > > > > > > > > > > I compile-tested allmodconfig for the latest kernel as of writing, > > > > > it detected the following: > > > > > > > > > > warning: same basename '88pm800.ko' if the following are built as modules: > > > > > drivers/regulator/88pm800.ko > > > > > drivers/mfd/88pm800.ko > > > > > warning: same basename 'adv7511.ko' if the following are built as modules: > > > > > drivers/gpu/drm/bridge/adv7511/adv7511.ko > > > > > drivers/media/i2c/adv7511.ko > > > > > warning: same basename 'asix.ko' if the following are built as modules: > > > > > drivers/net/phy/asix.ko > > > > > drivers/net/usb/asix.ko > > > > > warning: same basename 'coda.ko' if the following are built as modules: > > > > > fs/coda/coda.ko > > > > > drivers/media/platform/coda/coda.ko > > > > > warning: same basename 'realtek.ko' if the following are built as modules: > > > > > drivers/net/phy/realtek.ko > > > > > drivers/net/dsa/realtek.ko > > > > > > > > > > Reported-by: Stephen Rothwell <sfr@xxxxxxxxxxxxxxxx> > > > > > Signed-off-by: Masahiro Yamada <yamada.masahiro@xxxxxxxxxxxxx> > > > > > > > > That looks great! > > > > > > > > > --- > > > > > > > > > > [Alternative fix ? ] > > > > > > > > > > I do not know about the user experience of modprobe etc. > > > > > when two different modules have the same name. > > > > > It does not matter if this is correctly handled by modules.order? > > > > > > > > > > If this is just a problem of the build system, it is pretty easy to fix. > > > > > For example, if we prepend the directory path, parallel build will > > > > > never write to the same file simultanously. > > > > > > > > > > asix.mod -> drivers/net/phy/asix.mod > > > > > asix.mod -> drivers/net/usb/asix.mod > > > > > > > > non-unique module names cause all kinds of problems, and > > > > modprobe can certainly not handle them correctly, and there > > > > are issues with symbols exported from a module when another > > > > one has the same name. > > > > > > /sys/modules/ will fall over when this happens as well. I thought we > > > had the "rule" that module names had to be unique, I guess it was only a > > > matter of time before they started colliding :( > > > > > > So warning is good, but forbidding this is better, as things will break. > > > > > > Or we need to fix up the places where things will break. > > > > > > If we intentionally break the build, > > we need to send fix-up patches to subsystems first. > > True, but those builds are already broken if anyone tries to use them :) > > A warning for now would be nice, that way we can find these and know to > fix them up over time. Yes, I think it is a fair point. Start this with warning, then people will soon notice the problem. Turning it into error is easy once we fix all instances. -- Best Regards Masahiro Yamada
