Messages in this thread Patch in this message | | | Subject | Re: [PATCH 6/7] selftests: only compile userfaultfd for x86 and powperpc | From | Michael Ellerman <> | Date | Tue, 08 Sep 2015 19:54:13 +1000 |
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On Tue, 2015-09-08 at 17:15 +0800, Bamvor Zhang Jian wrote: > Hi, Michael > > I thought I reply to you, but ... > > On 08/31/2015 11:26 AM, Michael Ellerman wrote: > > On Fri, 2015-08-14 at 21:43 +0800, Bamvor Jian Zhang wrote: > >> Signed-off-by: Bamvor Jian Zhang <bamvor.zhangjian@linaro.org> > >> --- > >> tools/testing/selftests/vm/Makefile | 12 ++++++++++++ > >> 1 file changed, 12 insertions(+) > >> > >> diff --git a/tools/testing/selftests/vm/Makefile b/tools/testing/selftests/vm/Makefile > >> index bb888c6..4dd6e4f 100644 > >> --- a/tools/testing/selftests/vm/Makefile > >> +++ b/tools/testing/selftests/vm/Makefile > >> @@ -1,5 +1,15 @@ > >> # Makefile for vm selftests > >> > >> +uname_M := $(shell uname -m 2>/dev/null || echo not) > >> +ARCH ?= $(shell echo $(uname_M) | sed -e s/i.86/i386/ -e s/ppc.*/powerpc/) > >> + > >> +ifeq ($(ARCH),powerpc) > >> +support_userfaultfd = yes > >> +endif > >> +ifeq ($(ARCH),x86) > >> +support_userfaultfd = yes > >> +endif > >> + > >> CFLAGS = -Wall > >> BINARIES = compaction_test > >> BINARIES += hugepage-mmap > >> @@ -9,7 +19,9 @@ BINARIES += mlock2-tests > >> BINARIES += on-fault-limit > >> BINARIES += thuge-gen > >> BINARIES += transhuge-stress > >> +ifdef support_userfaultfd > >> BINARIES += userfaultfd > >> +endif > >> > >> all: $(BINARIES) > >> %: %.c > > > > > > This is nasty. It means when userfaultfd gets implemented for other arches > > someone has to remember to update the logic here, which they won't. > > > > Instead the C program should just do nothing when __NR_userfaultfd is not defined, eg: > > > > #ifdef __NR_userfaultfd > > > > int main(int argc, char **argv) > > { > > ... > > } > > > > #else > > > > int main(void) > > { > > printf("skip: Skipping userfaultfd test\n"); > > return 0; > > } > > #endif > > > > > > This way when the syscall is implemented for other arches the test will just > > start working. > > > > cheers > > > > > When read the following code, It seems that sometimes __NR_userfaultfd is not > defined but the syscall is exist. I am not sure why these piece is needed. > cc'd c > > #ifndef __NR_userfaultfd > #ifdef __x86_64__ > #define __NR_userfaultfd 323 > #elif defined(__i386__) > #define __NR_userfaultfd 374 > #elif defined(__powewrpc__) > #define __NR_userfaultfd 364 > #else > #error "missing __NR_userfaultfd definition" > #endif > #endif > > Do you mean that we should remove the above code?
Well yes, it would need to be removed to make the logic I suggested work.
I'm not sure those #defines actually help in practice, because if the syscall number is not defined then linux/userfaultfd.h will not exist and the whole test will not compile anyway.
I was suggesting something like this, which has the properties of: - not breaking the build on arches that don't have the syscall - still printing a notice on arches that don't have the syscall, both at build time and runtime. - building correctly on an arch as soon as that arch implements the syscall, with no extra changes required.
cheers
diff --git a/tools/testing/selftests/vm/userfaultfd.c b/tools/testing/selftests/vm/userfaultfd.c index 2bf1fc3f562b..652c9d805006 100644 --- a/tools/testing/selftests/vm/userfaultfd.c +++ b/tools/testing/selftests/vm/userfaultfd.c @@ -64,19 +64,10 @@ #include <sys/syscall.h> #include <sys/ioctl.h> #include <pthread.h> -#include <linux/userfaultfd.h> -#ifndef __NR_userfaultfd -#ifdef __x86_64__ -#define __NR_userfaultfd 323 -#elif defined(__i386__) -#define __NR_userfaultfd 374 -#elif defined(__powewrpc__) -#define __NR_userfaultfd 364 -#else -#error "missing __NR_userfaultfd definition" -#endif -#endif +#ifdef __NR_userfaultfd + +#include <linux/userfaultfd.h> static unsigned long nr_cpus, nr_pages, nr_pages_per_cpu, page_size; @@ -636,3 +627,15 @@ int main(int argc, char **argv) nr_pages, nr_pages_per_cpu); return userfaultfd_stress(); } + +#else /* ! __NR_userfaultfd */ + +#warning "missing __NR_userfaultfd definition" + +int main(void) +{ + printf("skip: Skipping userfaultfd test (missing __NR_userfaultfd)\n"); + return 0; +} + +#endif
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