From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Richter Subject: [PATCH] perf build: Build error in libbpf with EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2" Date: Mon, 23 Jul 2018 15:45:01 +0200 Message-ID: <20180723134501.11180-1-tmricht@linux.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Return-path: Sender: linux-kernel-owner@vger.kernel.org To: linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, acme@kernel.org, wangnan0@huawei.com Cc: brueckner@linux.vnet.ibm.com, schwidefsky@de.ibm.com, heiko.carstens@de.ibm.com, Thomas Richter List-Id: linux-perf-users.vger.kernel.org commit a5b8bd47dcc57 ("bpf tools: Collect eBPF programs from their own sections") cause a compiler error when building the perf tool in the linux-next tree. 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) Here is the error message: [root@p23lp27] # make V=1 EXTRA_CFLAGS="-Wp,-D_FORTIFY_SOURCE=2 -O2" [...] make -f /home6/tmricht/linux-next/tools/build/Makefile.build dir=./util/scripting-engines obj=libperf libbpf.c: In function ‘bpf_object__elf_collect’: libbpf.c:811:15: error: ignoring return value of ‘strerror_r’, declared with attribute warn_unused_result [-Werror=unused-result] strerror_r(-err, errmsg, sizeof(errmsg)); ^ 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 by using strerror_r return value in pr_warning statement. Also fixes a possible initialization issue. Cc: Wang Nan Signed-off-by: Thomas Richter --- tools/lib/bpf/libbpf.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index 955f8eafbf41..c70785ea903c 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -808,9 +808,9 @@ static int bpf_object__elf_collect(struct bpf_object *obj) if (err) { char errmsg[STRERR_BUFSIZE]; - strerror_r(-err, errmsg, sizeof(errmsg)); pr_warning("failed to alloc program %s (%s): %s", - name, obj->path, errmsg); + name, obj->path, + strerror_r(-err, errmsg, sizeof(errmsg))); } } else if (sh.sh_type == SHT_REL) { void *reloc = obj->efile.reloc; @@ -2334,7 +2334,7 @@ bpf_perf_event_read_simple(void *mem, unsigned long size, __u64 data_tail = header->data_tail; __u64 data_head = header->data_head; void *base, *begin, *end; - int ret; + int ret = 0; asm volatile("" ::: "memory"); /* in real code it should be smp_rmb() */ if (data_head == data_tail) -- 2.16.4