Messages in this thread | | | Date | Fri, 27 Jul 2018 10:59:23 -0700 | From | Jakub Kicinski <> | Subject | Re: [PATCH] perf build: Build error in libbpf missing initialization |
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On Fri, 27 Jul 2018 10:21:26 +0200, Thomas Richter wrote: > In linux-next tree compiling the perf tool with additional make flags > "EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2" > causes a compiler error. It is the warning > 'variable may be used uninitialized' > which is treated as error: > > I compile it using a FEDORA 28 installation, my gcc compiler version: > gcc (GCC) 8.0.1 20180324 (Red Hat 8.0.1-0.20) > > The file that causes the error is tools/lib/bpf/libbpf.c > > Here is the error message: > > [root@p23lp27] # make V=1 EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2" > [...] > Makefile.config:849: No openjdk development package found, please > install JDK package, e.g. openjdk-8-jdk, java-1.8.0-openjdk-devel > Warning: Kernel ABI header at 'tools/include/uapi/linux/if_link.h' > differs from latest version at 'include/uapi/linux/if_link.h' > CC libbpf.o > libbpf.c: In function ‘bpf_perf_event_read_simple’: > libbpf.c:2342:6: error: ‘ret’ may be used uninitialized in this > function [-Werror=maybe-uninitialized] > int ret; > ^ > cc1: all warnings being treated as errors > mv: cannot stat './.libbpf.o.tmp': No such file or directory > /home6/tmricht/linux-next/tools/build/Makefile.build:96: recipe for target 'libbpf.o' failed > > Fix this warning and add an addition check at the beginning > of the while loop. > > Cc: Alexei Starovoitov <ast@kernel.org> > Cc: Daniel Borkmann <daniel@iogearbox.net> > > Suggested-by: Jakub Kicinski <jakub.kicinski@netronome.com> > Signed-off-by: Thomas Richter <tmricht@linux.ibm.com>
Ah, you already sent this, LGTM, thanks Thomas!
> tools/lib/bpf/libbpf.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c > index 73465caa33ba..66965ca96113 100644 > --- a/tools/lib/bpf/libbpf.c > +++ b/tools/lib/bpf/libbpf.c > @@ -2349,6 +2349,8 @@ bpf_perf_event_read_simple(void *mem, unsigned long size, > > begin = base + data_tail % size; > end = base + data_head % size; > + if (begin == end) > + return LIBBPF_PERF_EVENT_ERROR; > > while (begin != end) { > struct perf_event_header *ehdr;
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