On Wed, Jul 20, 2022 at 02:40:33PM -0700, Florian Fainelli wrote: > On 7/20/22 14:32, Darrick J. Wong wrote: > > On Wed, Jul 20, 2022 at 01:53:07PM -0700, Florian Fainelli wrote: > >> MIPS platforms building with recent kernel headers and the musl-libc toolchain > >> will expose the following build failure: > >> > >> mmap.c: In function 'mmap_f': > >> mmap.c:196:12: error: 'MAP_SYNC' undeclared (first use in this function); did you mean 'MS_SYNC'? > >> 196 | flags = MAP_SYNC | MAP_SHARED_VALIDATE; > >> | ^~~~~~~~ > >> | MS_SYNC > >> mmap.c:196:12: note: each undeclared identifier is reported only once for each function it appears in > >> make[4]: *** [../include/buildrules:81: mmap.o] Error 1 > > > > Didn't we already fix this? > > https://lore.kernel.org/linux-xfs/20220508193029.1277260-1-fontaine.fabrice@xxxxxxxxx/ > > > > Didn't we already fix this? > > https://lore.kernel.org/linux-xfs/20181116162346.456255382F@xxxxxxxxxxxxxxxx/ > > First off, I was not aware of these two proposed solutions so > apologies for submitting a third (are there more) one. No worries :) > The common problem I see with both proposed patches is that they > specifically tackle io/mmap.c when really any inclusion order of > linux.h OH, yikes, this is what goes into include/linux.h (which is also exported as /usr/include/xfs/linux.h): #ifndef HAVE_MAP_SYNC #define MAP_SYNC 0 #define MAP_SHARED_VALIDATE 0 #else #include <asm-generic/mman.h> #include <asm-generic/mman-common.h> #endif /* HAVE_MAP_SYNC */ xfsprogs has no business exporting redefinitions of kernel symbols to userspace. This innocent looking program on an x64 system: #include <stdio.h> #include <sys/mman.h> #include <xfs/xfs.h> int main(int argc, char *argv[]) { printf("MAP_SYNC 0x%x\n", MAP_SYNC); } prints "MAP_SYNC 0x0", not the "MAP_SYNC 0x80000" that you'd expect. Ok, all this override stuff needs to die. > and sys/mman.h could and would lead to the the same problem to > re-surface somewhere else in a different file. So sure enough there is > only mmap.c now, but it has been identified that this specific include > order is problematic so we ought to address it in a general way. Exactly. > > > > Oh, I guess the maintainer didn't apply either of these patches, so this > > has been broken for years. > > Fabrice's patch is only a few months old, and but > "info@xxxxxxxxxxxxxxxxx"'s is nearly 4 years old... Yep. > > > > Well... MAP_SYNC has been with us for a while now, perhaps it makes more > > sense to remove all the override cruft and make xfs_io not export -S if > > if neither kernel headers nor libc define it? > > Sure that would work too, but we will still end up with some MAP_SYNC > conditional code, so the original intent of always defining it seemed > laudable. Oh no, if I cleaned up xfs_io mmap command, I'd also get rid of the override stuff too. Working on it... --D > > > > > --D > > > >> > >> The reason for that is that the linux.h header file which intends to provide a fallback definition for MAP_SYNC and MAP_SHARED_VALIDATE is included too early through: > >> > >> input.h -> libfrog/projects.h -> xfs.h -> linux.h and this happens > >> *before* sys/mman.h is included. > >> > >> sys/mman.h -> bits/mman.h which has a: > >> #undef MAP_SYNC > >> > >> see: https://git.musl-libc.org/cgit/musl/tree/arch/mips/bits/mman.h#n21 > >> > >> The end result is that sys/mman.h being included for the first time > >> ends-up overriding the HAVE_MAP_SYNC fallbacks. > >> > >> To remedy that, make sure that linux.h is updated to include sys/mman.h > >> such that its fallbacks are independent of the inclusion order. As a > >> consequence this forces us to ensure that we do not re-define > >> accidentally MAP_SYNC or MAP_SHARED_VALIDATE so we protect against that. > >> > >> Fixes: dad796834cb9 ("xfs_io: add MAP_SYNC support to mmap()") > >> Signed-off-by: Florian Fainelli <f.fainelli@xxxxxxxxx> > >> --- > >> include/linux.h | 5 +++++ > >> 1 file changed, 5 insertions(+) > >> > >> diff --git a/include/linux.h b/include/linux.h > >> index 3d9f4e3dca80..c3cc8e30c677 100644 > >> --- a/include/linux.h > >> +++ b/include/linux.h > >> @@ -252,8 +252,13 @@ struct fsxattr { > >> #endif > >> > >> #ifndef HAVE_MAP_SYNC > >> +#include <sys/mman.h> > >> +#ifndef MAP_SYNC > >> #define MAP_SYNC 0 > >> +#endif > >> +#ifndef MAP_SHARED_VALIDATE > >> #define MAP_SHARED_VALIDATE 0 > >> +#endif > >> #else > >> #include <asm-generic/mman.h> > >> #include <asm-generic/mman-common.h> > >> -- > >> 2.25.1 > >> > > > -- > Florian
