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. 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 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. > > 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... > > 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. > > --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
