From: Jakub Kicinski <jakub.kicinski@netronome.com>
To: Thomas Richter <tmricht@linux.ibm.com>
Cc: daniel@iogearbox.net, ast@kernel.org, netdev@vger.kernel.org,
linux-kernel@vger.kernel.org, heiko.carstens@de.ibm.com,
brueckner@linux.vnet.ibm.com, schwidefsky@de.ibm.com
Subject: Re: [PATCH] perf build: Build error in libbpf missing initialization
Date: Fri, 27 Jul 2018 10:59:23 -0700 [thread overview]
Message-ID: <20180727105923.2d5da6aa@cakuba.netronome.com> (raw)
In-Reply-To: <20180727082126.87530-1-tmricht@linux.ibm.com>
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;
next prev parent reply other threads:[~2018-07-27 17:59 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-27 8:21 [PATCH] perf build: Build error in libbpf missing initialization Thomas Richter
2018-07-27 17:59 ` Jakub Kicinski [this message]
2018-07-27 19:31 ` Daniel Borkmann
2018-07-27 19:56 ` Jakub Kicinski
2018-07-28 19:30 ` Daniel Borkmann
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