From patchwork Tue Nov 10 16:41:02 2015 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Adhemerval Zanella Netto X-Patchwork-Id: 9643 Received: (qmail 107569 invoked by alias); 10 Nov 2015 16:41:15 -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 107555 invoked by uid 89); 10 Nov 2015 16:41:14 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.3 required=5.0 tests=AWL, BAYES_00, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-yk0-f179.google.com X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id; bh=TYiOyNod6UON3Nv/wGXq5U4zys6pma0ngIXhS8MfZxs=; b=YBbnJDk4GZdFWV+JwJ45AoM/RX6/AVdyL16TYdZuofQ4nkJJJZbRkPqlcVF5ZxpXfY SsflxTTMvMep7yDv2deqGTTmfE0qvkFXymGImnT+oMQQyjqHEqQ78MAt/JL1KVBbT9UI Tt2JSaQBFjKehOnYUYVQKS7P9dWapFwjAeElUgQYNP9gSs4mAYcy1hu8ZmuM6A3pUC+9 kxUcU2PBjIDUkuS7Am1aFpmbJAGv2Jt01IQTMzeU5K0f1bUSeOq2Ztx97ZPsAzWUiBSX fa9b8Q1MnKWDTqqgn1EhV/7SRO/VjbsZBemBF5DLYyT1kZwzFWhhnnRl3ktzClXDfdRx Dd8A== X-Gm-Message-State: ALoCoQmViJ+xIzOgO67CJoMDcx4ic1ad9+aCmxR4+0dgcse3IiOL0WpsP2cXslOMK2D7kXKrImcg X-Received: by 10.13.242.196 with SMTP id b187mr4069677ywf.241.1447173670318; Tue, 10 Nov 2015 08:41:10 -0800 (PST) From: Adhemerval Zanella To: libc-alpha@sourceware.org Cc: Adhemerval Zanella Subject: [PATCH v3] Remove signal handling for nanosleep (bug 16364) Date: Tue, 10 Nov 2015 14:41:02 -0200 Message-Id: <1447173662-5776-1-git-send-email-adhemerval.zanella@linaro.org> From: Adhemerval Zanella Linux 2.6.32 and forward do not show the issue regarding SysV SIGCHLD vs. SIG_IGN for nanosleep which make it feasible to use it for sleep implementation without requiring any hacking to handle the spurious wake up. The issue is likely being fixed before 2.6 and git history [1] [2]. This patch simplifies the sleep code to call nanosleep directly by using the posix default version. It also removes the early cancellation tests for zero argument, since nanosleep will handle cancellation in this case. [1] https://lkml.org/lkml/2004/11/25/5 [2] https://lkml.org/lkml/2003/11/8/50 Checked on x86_64, ppc64le, and aarch64. [BZ #16364] * sysdeps/unix/sysv/linux/sleep.c: Remove file * sysdeps/posix/sleep.c (__sleep): Simplify cancellation handling. Changes from previous version: - Dropped racy test. --- sysdeps/posix/sleep.c | 9 --- sysdeps/unix/sysv/linux/sleep.c | 149 ---------------------------------------- 3 files changed, 6 insertions(+), 158 deletions(-) delete mode 100644 sysdeps/unix/sysv/linux/sleep.c diff --git a/sysdeps/posix/sleep.c b/sysdeps/posix/sleep.c index 75d9c18..80beb2a 100644 --- a/sysdeps/posix/sleep.c +++ b/sysdeps/posix/sleep.c @@ -32,15 +32,6 @@ unsigned int __sleep (unsigned int seconds) { - /* This is not necessary but some buggy programs depend on it. */ - if (__glibc_unlikely (seconds == 0)) - { -#ifdef CANCELLATION_P - CANCELLATION_P (THREAD_SELF); -#endif - return 0; - } - int save_errno = errno; const unsigned int max diff --git a/sysdeps/unix/sysv/linux/sleep.c b/sysdeps/unix/sysv/linux/sleep.c deleted file mode 100644 index 2a06d5a..0000000 --- a/sysdeps/unix/sysv/linux/sleep.c +++ /dev/null @@ -1,149 +0,0 @@ -/* Implementation of the POSIX sleep function using nanosleep. - Copyright (C) 1996-2015 Free Software Foundation, Inc. - This file is part of the GNU C Library. - Contributed by Ulrich Drepper , 1996. - - 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 /* For the real memset prototype. */ -#include -#include -#include - - -#if 0 -static void -cl (void *arg) -{ - (void) __sigprocmask (SIG_SETMASK, arg, (sigset_t *) NULL); -} -#endif - - -/* We are going to use the `nanosleep' syscall of the kernel. But the - kernel does not implement the stupid SysV SIGCHLD vs. SIG_IGN - behaviour for this syscall. Therefore we have to emulate it here. */ -unsigned int -__sleep (unsigned int seconds) -{ - const unsigned int max - = (unsigned int) (((unsigned long int) (~((time_t) 0))) >> 1); - struct timespec ts; - sigset_t set, oset; - unsigned int result; - - /* This is not necessary but some buggy programs depend on this. */ - if (__glibc_unlikely (seconds == 0)) - { -#ifdef CANCELLATION_P - CANCELLATION_P (THREAD_SELF); -#endif - return 0; - } - - ts.tv_sec = 0; - ts.tv_nsec = 0; - again: - if (sizeof (ts.tv_sec) <= sizeof (seconds)) - { - /* Since SECONDS is unsigned assigning the value to .tv_sec can - overflow it. In this case we have to wait in steps. */ - ts.tv_sec += MIN (seconds, max); - seconds -= (unsigned int) ts.tv_sec; - } - else - { - ts.tv_sec = (time_t) seconds; - seconds = 0; - } - - /* Linux will wake up the system call, nanosleep, when SIGCHLD - arrives even if SIGCHLD is ignored. We have to deal with it - in libc. We block SIGCHLD first. */ - __sigemptyset (&set); - __sigaddset (&set, SIGCHLD); - if (__sigprocmask (SIG_BLOCK, &set, &oset)) - return -1; - - /* If SIGCHLD is already blocked, we don't have to do anything. */ - if (!__sigismember (&oset, SIGCHLD)) - { - int saved_errno; - struct sigaction oact; - - __sigemptyset (&set); - __sigaddset (&set, SIGCHLD); - - /* We get the signal handler for SIGCHLD. */ - if (__sigaction (SIGCHLD, (struct sigaction *) NULL, &oact) < 0) - { - saved_errno = errno; - /* Restore the original signal mask. */ - (void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); - __set_errno (saved_errno); - return -1; - } - - /* Note the sleep() is a cancellation point. But since we call - nanosleep() which itself is a cancellation point we do not - have to do anything here. */ - if (oact.sa_handler == SIG_IGN) - { - //__libc_cleanup_push (cl, &oset); - - /* We should leave SIGCHLD blocked. */ - while (1) - { - result = __nanosleep (&ts, &ts); - - if (result != 0 || seconds == 0) - break; - - if (sizeof (ts.tv_sec) <= sizeof (seconds)) - { - ts.tv_sec = MIN (seconds, max); - seconds -= (unsigned int) ts.tv_nsec; - } - } - - //__libc_cleanup_pop (0); - - saved_errno = errno; - /* Restore the original signal mask. */ - (void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); - __set_errno (saved_errno); - - goto out; - } - - /* We should unblock SIGCHLD. Restore the original signal mask. */ - (void) __sigprocmask (SIG_SETMASK, &oset, (sigset_t *) NULL); - } - - result = __nanosleep (&ts, &ts); - if (result == 0 && seconds != 0) - goto again; - - out: - if (result != 0) - /* Round remaining time. */ - result = seconds + (unsigned int) ts.tv_sec + (ts.tv_nsec >= 500000000L); - - return result; -} -weak_alias (__sleep, sleep)