Buildresult: linus/um-defconfig/um-x86_64 built on Jun 12 2022, 06:46

kisskb

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Status:	OK
Date/Time:	Jun 12 2022, 06:46
Duration:	0:00:24.847097
Builder:	ka7
Revision:	iov_iter: fix build issue due to possible type mis-match (`1c27f1fc1549f0e470429f5497a76ad28a37f21a)`
Target:	linus/um-defconfig/um-x86_64
Branch:	linus
Compiler:	um-x86_64 (x86_64-linux-gcc.br_real (Buildroot 2017.05) 5.4.0 / GNU ld (GNU Binutils) 2.27)
Config:	defconfig (download)
Log:	Download original No warnings found in log. Full Log # git rev-parse -q --verify 1c27f1fc1549f0e470429f5497a76ad28a37f21a^{commit} 1c27f1fc1549f0e470429f5497a76ad28a37f21a already have revision, skipping fetch # git checkout -q -f -B kisskb 1c27f1fc1549f0e470429f5497a76ad28a37f21a # git clean -qxdf # < git log -1 # commit 1c27f1fc1549f0e470429f5497a76ad28a37f21a # Author: Linus Torvalds <torvalds@linux-foundation.org> # Date: Sat Jun 11 10:30:20 2022 -0700 # # iov_iter: fix build issue due to possible type mis-match # # Commit 6c77676645ad ("iov_iter: Fix iter_xarray_get_pages{,_alloc}()") # introduced a problem on some 32-bit architectures (at least arm, xtensa, # csky,sparc and mips), that have a 'size_t' that is 'unsigned int'. # # The reason is that we now do # # min(nr * PAGE_SIZE - offset, maxsize); # # where 'nr' and 'offset' and both 'unsigned int', and PAGE_SIZE is # 'unsigned long'. As a result, the normal C type rules means that the # first argument to 'min()' ends up being 'unsigned long'. # # In contrast, 'maxsize' is of type 'size_t'. # # Now, 'size_t' and 'unsigned long' are always the same physical type in # the kernel, so you'd think this doesn't matter, and from an actual # arithmetic standpoint it doesn't. # # But on 32-bit architectures 'size_t' is commonly 'unsigned int', even if # it could also be 'unsigned long'. In that situation, both are unsigned # 32-bit types, but they are not the same type. # # And as a result 'min()' will complain about the distinct types (ignore # the "pointer types" part of the error message: that's an artifact of the # way we have made 'min()' check types for being the same): # # lib/iov_iter.c: In function 'iter_xarray_get_pages': # include/linux/minmax.h:20:35: error: comparison of distinct pointer types lacks a cast [-Werror] # 20 \| (!!(sizeof((typeof(x) )1 == (typeof(y) )1))) # \| ^~ # lib/iov_iter.c:1464:16: note: in expansion of macro 'min' # 1464 \| return min(nr * PAGE_SIZE - offset, maxsize); # \| ^~~ # # This was not visible on 64-bit architectures (where we always define # 'size_t' to be 'unsigned long'). # # Force these cases to use 'min_t(size_t, x, y)' to make the type explicit # and avoid the issue. # # [ Nit-picky note: technically 'size_t' doesn't have to match 'unsigned # long' arithmetically. We've certainly historically seen environments # with 16-bit address spaces and 32-bit 'unsigned long'. # # Similarly, even in 64-bit modern environments, 'size_t' could be its # own type distinct from 'unsigned long', even if it were arithmetically # identical. # # So the above type commentary is only really descriptive of the kernel # environment, not some kind of universal truth for the kinds of wild # and crazy situations that are allowed by the C standard ] # # Reported-by: Sudip Mukherjee <sudipm.mukherjee@gmail.com> # Link: https://lore.kernel.org/all/YqRyL2sIqQNDfky2@debian/ # Cc: Jeff Layton <jlayton@kernel.org> # Cc: David Howells <dhowells@redhat.com> # Cc: Al Viro <viro@zeniv.linux.org.uk> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-gcc --version # < /opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux-ld --version # < git log --format=%s --max-count=1 1c27f1fc1549f0e470429f5497a76ad28a37f21a # < make -s -j 32 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 defconfig # < make -s -j 32 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 help # make -s -j 32 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 olddefconfig # make -s -j 32 ARCH=um O=/kisskb/build/linus_um-defconfig_um-x86_64 CROSS_COMPILE=/opt/cross/kisskb/fe-x86-64-core-i7-2017.05/bin/x86_64-linux- SUBARCH=x86_64 LINK linux Completed OK # rm -rf /kisskb/build/linus_um-defconfig_um-x86_64 # Build took: 0:00:24.847097

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