From patchwork Fri Jun 2 14:21:00 2017 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Florian Weimer X-Patchwork-Id: 20739 Received: (qmail 51581 invoked by alias); 2 Jun 2017 14:21:02 -0000 Mailing-List: contact libc-alpha-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Subscribe: List-Archive: List-Post: List-Help: , Sender: libc-alpha-owner@sourceware.org Delivered-To: mailing list libc-alpha@sourceware.org Received: (qmail 51552 invoked by uid 89); 2 Jun 2017 14:21:01 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-26.9 required=5.0 tests=BAYES_00, GIT_PATCH_0, GIT_PATCH_1, GIT_PATCH_2, GIT_PATCH_3, RP_MATCHES_RCVD, SPF_HELO_PASS autolearn=ham version=3.3.2 spammy=928 X-HELO: mx1.redhat.com DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com E3C42C04B92B Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx07.extmail.prod.ext.phx2.redhat.com; spf=pass smtp.mailfrom=fweimer@redhat.com DKIM-Filter: OpenDKIM Filter v2.11.0 mx1.redhat.com E3C42C04B92B Date: Fri, 02 Jun 2017 16:21:00 +0200 To: libc-alpha@sourceware.org Subject: [PATCH] sysconf: Use conservative default for _SC_NPROCESSORS_ONLN [BZ #21542] User-Agent: Heirloom mailx 12.5 7/5/10 MIME-Version: 1.0 Message-Id: <20170602142100.DA8D0404970C8@oldenburg.str.redhat.com> From: fweimer@redhat.com (Florian Weimer) 2017-06-02 Florian Weimer [BZ #21542] * sysdeps/unix/sysv/linux/getsysstats.c (__get_nprocs): Default to two if no accurate information is available. * posix/tst-sysconf-empty-chroot.c: New file. * posix/Makefile (tests): Add it. diff --git a/posix/Makefile b/posix/Makefile index 52b022c..4246f24 100644 --- a/posix/Makefile +++ b/posix/Makefile @@ -92,7 +92,8 @@ tests := test-errno tstgetopt testfnm runtests runptests \ tst-pathconf tst-getaddrinfo4 tst-rxspencer-no-utf8 \ tst-fnmatch3 bug-regex36 tst-getaddrinfo5 \ tst-posix_spawn-fd tst-posix_spawn-setsid \ - tst-posix_fadvise tst-posix_fadvise64 + tst-posix_fadvise tst-posix_fadvise64 \ + tst-sysconf-empty-chroot tests-internal := bug-regex5 bug-regex20 bug-regex33 \ tst-rfc3484 tst-rfc3484-2 tst-rfc3484-3 xtests := bug-ga2 diff --git a/posix/tst-sysconf-empty-chroot.c b/posix/tst-sysconf-empty-chroot.c new file mode 100644 index 0000000..dd3b94b --- /dev/null +++ b/posix/tst-sysconf-empty-chroot.c @@ -0,0 +1,95 @@ +/* Test sysconf with an empty chroot. + Copyright (C) 2017 Free Software Foundation, Inc. + This file is part of the GNU C Library. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, see + . */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +/* Check for an SMP system in a forked process, so that the parent + process does not cache the value. */ +static void +is_smp_callback (void *closure) +{ + bool *result = closure; + + long cpus = sysconf (_SC_NPROCESSORS_ONLN); + TEST_VERIFY_EXIT (cpus > 0); + *result = cpus != 1; +} + +static bool +is_smp (void) +{ + bool *result = support_shared_allocate (sizeof (*result)); + support_isolate_in_subprocess (is_smp_callback, result); + bool result_copy = *result; + support_shared_free (result); + return result_copy; +} + +static char *path_chroot; + +/* Prepare an empty directory, to be used as a chroot. */ +static void +prepare (int argc, char **argv) +{ + path_chroot = xasprintf ("%s/tst-resolv-res_init-XXXXXX", test_dir); + if (mkdtemp (path_chroot) == NULL) + FAIL_EXIT1 ("mkdtemp (\"%s\"): %m", path_chroot); + add_temp_file (path_chroot); +} + +/* The actual test. Run it in a subprocess, so that the test harness + can remove the temporary directory in --direct mode. */ +static void +chroot_callback (void *closure) +{ + xchroot (path_chroot); + long cpus = sysconf (_SC_NPROCESSORS_ONLN); + printf ("info: sysconf (_SC_NPROCESSORS_ONLN) in chroot: %ld\n", cpus); + TEST_VERIFY (cpus > 0); + TEST_VERIFY (cpus != 1); + _exit (0); +} + +static int +do_test (void) +{ + if (!is_smp ()) + { + printf ("warning: test not supported on uniprocessor system\n"); + return EXIT_UNSUPPORTED; + } + + support_become_root (); + if (!support_can_chroot ()) + return EXIT_UNSUPPORTED; + + support_isolate_in_subprocess (chroot_callback, NULL); + + return 0; +} + +#define PREPARE prepare +#include diff --git a/sysdeps/unix/sysv/linux/getsysstats.c b/sysdeps/unix/sysv/linux/getsysstats.c index 63e4110..a0dd6eb 100644 --- a/sysdeps/unix/sysv/linux/getsysstats.c +++ b/sysdeps/unix/sysv/linux/getsysstats.c @@ -188,7 +188,10 @@ __get_nprocs (void) cp = buffer_end; re = buffer_end; - result = 1; + + /* Default to an SMP system in case we cannot obtain an accurate + number. */ + result = 2; /* The /proc/stat format is more uniform, use it by default. */ fd = open_not_cancel_2 ("/proc/stat", flags);