From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758261AbaGOUUu (ORCPT ); Tue, 15 Jul 2014 16:20:50 -0400 Received: from mx0b-00082601.pphosted.com ([67.231.153.30]:37010 "EHLO mx0b-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1758132AbaGOUUs (ORCPT ); Tue, 15 Jul 2014 16:20:48 -0400 Date: Tue, 15 Jul 2014 13:20:23 -0700 From: Martin Lau To: Steven Rostedt CC: , Subject: Re: [PATCH] ring-buffer: Fix polling on trace_pipe Message-ID: <20140715202021.GA12499@devbig242.prn2.facebook.com> References: <20140610060637.GA14045@devbig242.prn2.facebook.com> <20140610114915.5fe24841@gandalf.local.home> <20140611055814.GA30265@devbig242.prn2.facebook.com> <20140626183445.GA2663@devbig242.prn2.facebook.com> <20140626205327.5b526302@gandalf.local.home> <20140627065243.GA2826@devbig242.prn2.facebook.com> <20140710222030.GC12717@devbig242.prn2.facebook.com> <20140715154612.06afb98a@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20140715154612.06afb98a@gandalf.local.home> User-Agent: Mutt/1.5.20 (2009-12-10) X-Originating-IP: [192.168.57.29] X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:5.12.52,1.0.14,0.0.0000 definitions=2014-07-15_06:2014-07-15,2014-07-15,1970-01-01 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 kscore.is_bulkscore=2.94542168433054e-13 kscore.compositescore=0 circleOfTrustscore=22.4078557653337 compositescore=0.997695897463551 urlsuspect_oldscore=0.997695897463551 suspectscore=0 recipient_domain_to_sender_totalscore=0 phishscore=0 bulkscore=0 kscore.is_spamscore=0 recipient_to_sender_totalscore=0 recipient_domain_to_sender_domain_totalscore=62764 rbsscore=0.997695897463551 spamscore=0 recipient_to_sender_domain_totalscore=6 urlsuspectscore=0.9 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=7.0.1-1402240000 definitions=main-1407150220 X-FB-Internal: deliver Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Yes, I think it should go to both stable and 3.16. Thanks, --Martin On Tue, Jul 15, 2014 at 03:46:12PM -0400, Steven Rostedt wrote: > On Thu, 10 Jul 2014 15:20:30 -0700 > Martin Lau wrote: > > > Hi Steve, > > > > Do you have a chance to give it another try? > > > > OK, I finally got around to testing it. Yep I see your point. Do you > think it should go to 3.16 and stable? I can add it to my next git pull > request. > > Also, I modified your test such that it wouldn't hang on failure, but > detects that it hung and returns a exit value to add this to my > testing. That is, it exits with zero on success and non zero on failure. > > -- Steve > #include > #include > #include > #include > #include > #include > #include > #include > #include > #include > #include > #include > > static const char * debugfs_list[] = { > "/debug/tracing", > "/sys/kernel/debug/tracing", > "/d/tracing", > NULL, > }; > > static const char *debugfs; > static int markfd; > static int trace_pipe_fd; > > static void alog(const char *name, int ret) > { > printf("%d: %s: %d\n", getpid(), name, ret); > } > > static const char *find_debugfs(void) > { > struct stat st; > int i; > int r; > > for (i = 0; debugfs_list[i]; i++) { > r = stat(debugfs_list[i], &st); > if (r < 0) > continue; > if (S_ISDIR(st.st_mode)) > return debugfs_list[i]; > } > return NULL; > } > > static char * make_path(const char *file) > { > char *path; > int size; > > size = strlen(debugfs) + strlen(file) + 2; > path = malloc(size); > if (!path) { > perror("malloc"); > exit(-1); > } > sprintf(path, "%s/%s", debugfs, file); > return path; > } > > static void mark_write(const char *str) > { > int ret; > ret = write(markfd, str, strlen(str)); > alog("write(markfd)", ret); > } > > static void read_trace_pipe(void) > { > char buf[1024]; > int r; > > while ((r = read(trace_pipe_fd, buf, 1024)) > 0) > printf("%.*s", r, buf); > } > > int main (int argc, char **argv) > { > struct epoll_event ee; > char *marker; > char *pipe; > int efd; > int ret; > pid_t dwrt_pid; > > debugfs = find_debugfs(); > if (!debugfs) { > fprintf(stderr, "Could not find debugfs\n"); > exit(-1); > } > > marker = make_path("trace_marker"); > pipe = make_path("trace_pipe"); > > markfd = open(marker, O_WRONLY); > if (markfd < 0) { > perror("marker"); > exit(-1); > } > trace_pipe_fd = open(pipe, O_RDONLY|O_NONBLOCK); > if (trace_pipe_fd < 0) { > perror("trace_pipe"); > exit(-1); > } > > efd = epoll_create(1); > if (efd < 0) { > perror("epoll_create"); > exit(-1); > } > > mark_write("some data"); > memset(&ee, 0, sizeof(ee)); > ee.events = EPOLLIN; > ret = epoll_ctl(efd, EPOLL_CTL_ADD, trace_pipe_fd, &ee); > if (ret < 0) { > perror("epoll_ctl"); > exit(-1); > } > alog("waiting data......", 0); > ret = epoll_wait(efd, &ee, 1, -1); > alog("epoll_wait()", ret); > read_trace_pipe(); > dwrt_pid = fork(); > assert(dwrt_pid != -1); > if (dwrt_pid > 0) { > int status; > sleep(10); > mark_write("more data"); > sleep(10); > ret = waitpid(dwrt_pid, &status, WNOHANG); > if (ret != dwrt_pid) { > alog("Poll never finished!", 0); > kill(dwrt_pid, 9); > exit(-1); > } > if (WEXITSTATUS(status) != 0) { > alog("Something failed on polling!", > WEXITSTATUS(status)); > exit(-1); > } > } else { > alog("waiting form more data......", 0); > ret = epoll_wait(efd, &ee, 1, -1); > alog("epoll_wait()", ret); > read_trace_pipe(); > if (ret < 0) > exit(errno); > } > exit (0); > }