From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753588AbcDSKGU (ORCPT ); Tue, 19 Apr 2016 06:06:20 -0400 Received: from mga04.intel.com ([192.55.52.120]:28487 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752648AbcDSKGS (ORCPT ); Tue, 19 Apr 2016 06:06:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.24,506,1455004800"; d="scan'208";a="787816128" Date: Tue, 19 Apr 2016 18:09:56 +0800 From: Philip Li To: Fengguang Wu Cc: Alexei Starovoitov , Arnd Bergmann , "David S . Miller" , netdev@vger.kernel.org, Steven Rostedt , Ingo Molnar , Alexei Starovoitov , Daniel Borkmann , linux-kernel@vger.kernel.org Subject: Re: [PATCH] bpf: avoid warning for wrong pointer cast Message-ID: <20160419100956.GB8836@intel.com> References: <1460838585-1248139-1-git-send-email-arnd@arndb.de> <20160417004740.GA80675@ast-mbp.thefacebook.com> <20160419023334.GC24067@wfg-t540p.sh.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20160419023334.GC24067@wfg-t540p.sh.intel.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Apr 19, 2016 at 10:33:34AM +0800, Fengguang Wu wrote: > Hi Alexei, > > On Sat, Apr 16, 2016 at 05:47:42PM -0700, Alexei Starovoitov wrote: > > On Sat, Apr 16, 2016 at 10:29:33PM +0200, Arnd Bergmann wrote: > > > Two new functions in bpf contain a cast from a 'u64' to a > > > pointer. This works on 64-bit architectures but causes a warning > > > on all 32-bit architectures: > > > > > > kernel/trace/bpf_trace.c: In function 'bpf_perf_event_output_tp': > > > kernel/trace/bpf_trace.c:350:13: error: cast to pointer from integer of different size [-Werror=int-to-pointer-cast] > > > u64 ctx = *(long *)r1; > > > > > > This changes the cast to first convert the u64 argument into a uintptr_t, > > > which is guaranteed to be the same size as a pointer. > > > > > > Signed-off-by: Arnd Bergmann > > > Fixes: 9940d67c93b5 ("bpf: support bpf_get_stackid() and bpf_perf_event_output() in tracepoint programs") > > > > Thanks. > > Acked-by: Alexei Starovoitov > > > > I guess I started to rely on 0-day build-bot too much. > > This patch has been in my tree for 2+ weeks and then in net-next and > > I didn't receive a single email from build-bot about this warning, > > though I do receive them for my other work-in-progress stuff. Odd. > > Fengguang, any idea why build-bot sometimes silent? > > Sorry I went off for some time.. Philip, would you help have a check? Hi Alexei, i have done some investigation for this. Fengguang, pls correct me if my understanding is wrong. 0day has caught the warning for f1ff54 commit around 2016-3-22, which considers the same warning in future is not new one, thus neglect it. rli9@inn /kbuild-tests/build-error$ cat kernel-trace-bpf_trace.c:warning:cast-to-pointer-from-integer-of-different-size kernel/trace/bpf_trace.c:345:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 2016-03-22 17:12:38 xian bpf:master:321e70e79c94e5e6394a882d567baac949b74000 i386-randconfig-x009-201612 f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec And for f1ff54's warning, 0day actually bisects to it, but then it checks the head of bpf/master at that time which is 321e70e, find the error is not existed, so it ignores the interim warning to not send email report. 2016-03-22_17:15:49 O: R: /kbuild/src/consumer/kernel/trace/bpf_trace.c:345:13: warning: cast to pointer from integer of different size [-Wint-to-pointer-cast] 2016-03-22_17:15:49 O: grep -h -r . /tmp/kernel/i386-randconfig-x009-201612/gcc-5/f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec/build-error # 0 errors 2016-03-22_17:15:49 O: grep -h -r . /tmp/kernel/i386-randconfig-x009-201612/gcc-5/f1ff543dbdd3eff53c8328cfb582f18e6c3d56ec/build-error/ # 0 errors 2016-03-22_17:15:49 O: /c/kernel-tests/list-head bpf:master:321e70e79c94e5e6394a882d567baac949b74000 i386-randconfig-x009-201612 2016-03-22_17:16:03 O: . 2016-03-22_17:16:03 O: .. 2016-03-22_17:16:03 O: kernel-trace-bpf_trace.c:warning:cast-to-pointer-from-integer-of-different-size 2016-03-22_17:16:03 O: 2016-03-22 17:16:03 don't email interim warnings 2016-03-22_17:16:03 O: 2016-03-22 17:16:03 error no longer exist in head bpf/master 321e70e79c94e5e6394a882d567baac949b74000, check /tmp/kernel/i386-randconfig-x009-201612/gcc-5/321e70e79c94e5e6394a882d567baac949b74000, errno 14 2016-03-22_17:16:03 O: 2016-03-22 17:16:03 Don't email interim warnings! what really happens to 321e70e is it has build error (i rerun it to confirm), which is reported at https://lists.01.org/pipermail/kbuild-all/2016-March/018625.html. So this is a possible change to be done in 0day to report the first bad commit when HEAD is build error. 2016-04-19_15:00:39 O: 2016-04-19 15:00 Running /kbuild-tests/build-queue/lkp-nex06-consumer/i386-randconfig-x009-201612-gcc-5-321e70e79c94e5e6394a882d567baac949b74000 2016-04-19_15:00:39 O: create new KBUILD_OUTPUT dir /kbuild/obj/consumer/i386-randconfig-x009-201612 2016-04-19_15:00:39 O: git checkout -B build-queue 321e70e79c94e5e6394a882d567baac949b74000 2016-04-19_15:07:08 E: 330 real 4732 user 629 sys 1620.50% cpu i386-randconfig-x009-201612 2016-04-19_15:07:13 O: status: FAIL: build error 2016-04-19_15:07:13 O: ERROR: "tcp_sendpage" [drivers/staging/lustre/lnet/klnds/socklnd/ksocklnd.ko] undefined! > > Thanks, > Fengguang