Buildresult: linus/assabet_defconfig/arm-gcc4.6 built on Apr 6 2018, 08:21

kisskb

Revisions | Branches | Compilers | Configs | Build Results | Build Failures |

Status:	OK
Date/Time:	Apr 6 2018, 08:21
Duration:	0:00:28.944757
Builder:	ka1
Revision:	kernel.h: Retain constant expression output for max()/min() (`3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91)`
Target:	linus/assabet_defconfig/arm-gcc4.6
Branch:	linus
Compiler:	arm-gcc4.6 (arm-unknown-linux-gnueabi-gcc (GCC) 4.6.3)
Config:	assabet_defconfig (download)
Log:	Download original Possible warnings (1) kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] Full Log # git rev-parse -q --verify 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91^{commit} 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 already have revision, skipping fetch # git checkout -q -f -B kisskb 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 # git clean -qxdf # < git log -1 # commit 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 # Author: Kees Cook <keescook@chromium.org> # Date: Fri Mar 30 18:52:36 2018 -0700 # # kernel.h: Retain constant expression output for max()/min() # # In the effort to remove all VLAs from the kernel[1], it is desirable to # build with -Wvla. However, this warning is overly pessimistic, in that # it is only happy with stack array sizes that are declared as constant # expressions, and not constant values. One case of this is the # evaluation of the max() macro which, due to its construction, ends up # converting constant expression arguments into a constant value result. # # All attempts to rewrite this macro with __builtin_constant_p() failed # with older compilers (e.g. gcc 4.4)[2]. However, Martin Uecker, # constructed[3] a mind-shattering solution that works everywhere. # Cthulhu fhtagn! # # This patch updates the min()/max() macros to evaluate to a constant # expression when called on constant expression arguments. This removes # several false-positive stack VLA warnings from an x86 allmodconfig build # when -Wvla is added: # # $ diff -u before.txt after.txt \| grep ^- # -drivers/input/touchscreen/cyttsp4_core.c:871:2: warning: ISO C90 forbids variable length array ‘ids’ [-Wvla] # -fs/btrfs/tree-checker.c:344:4: warning: ISO C90 forbids variable length array ‘namebuf’ [-Wvla] # -lib/vsprintf.c:747:2: warning: ISO C90 forbids variable length array ‘sym’ [-Wvla] # -net/ipv4/proc.c:403:2: warning: ISO C90 forbids variable length array ‘buff’ [-Wvla] # -net/ipv6/proc.c:198:2: warning: ISO C90 forbids variable length array ‘buff’ [-Wvla] # -net/ipv6/proc.c:218:2: warning: ISO C90 forbids variable length array ‘buff64’ [-Wvla] # # This also updates two cases where different enums were being compared # and explicitly casts them to int (which matches the old side-effect of # the single-evaluation code): one in tpm/tpm_tis_core.h, and one in # drm/drm_color_mgmt.c. # # [1] https://lkml.org/lkml/2018/3/7/621 # [2] https://lkml.org/lkml/2018/3/10/170 # [3] https://lkml.org/lkml/2018/3/20/845 # # Co-Developed-by: Linus Torvalds <torvalds@linux-foundation.org> # Co-Developed-by: Martin Uecker <Martin.Uecker@med.uni-goettingen.de> # Signed-off-by: Kees Cook <keescook@chromium.org> # Acked-by: Ingo Molnar <mingo@kernel.org> # Acked-by: Miguel Ojeda <miguel.ojeda.sandonis@gmail.com> # Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> # < /opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi-gcc --version # < git log --format=%s --max-count=1 3c8ba0d61d04ced9f8d9ff93977995a9e4e96e91 # < make -s -j 48 ARCH=arm O=/kisskb/build/linus_assabet_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi- assabet_defconfig # make -s -j 48 ARCH=arm O=/kisskb/build/linus_assabet_defconfig_arm CROSS_COMPILE=/opt/cross/kisskb/gcc-4.6.3-nolibc/arm-unknown-linux-gnueabi/bin/arm-unknown-linux-gnueabi- /kisskb/src/kernel/printk/printk.c: In function 'devkmsg_sysctl_set_loglvl': /kisskb/src/kernel/printk/printk.c:183:16: warning: 'old' may be used uninitialized in this function [-Wuninitialized] Completed OK # rm -rf /kisskb/build/linus_assabet_defconfig_arm # Build took: 0:00:28.944757

© Michael Ellerman 2006-2018.