From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Morton Subject: Re: [PATCH 02/18] flag parameters: paccept Date: Thu, 8 May 2008 15:38:22 -0700 Message-ID: <20080508153822.0c4dd6e9.akpm@linux-foundation.org> References: <200805062118.m46LI7SS004041@devserv.devel.redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org, netdev@vger.kernel.org, davidel@xmailserver.org, mtk.manpages@gmail.com, torvalds@linux-foundation.org, Roland McGrath , Oleg Nesterov To: Ulrich Drepper Return-path: Received: from smtp1.linux-foundation.org ([140.211.169.13]:55455 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754869AbYEHWjW (ORCPT ); Thu, 8 May 2008 18:39:22 -0400 In-Reply-To: <200805062118.m46LI7SS004041@devserv.devel.redhat.com> Sender: netdev-owner@vger.kernel.org List-ID: On Tue, 6 May 2008 17:18:07 -0400 Ulrich Drepper wrote: > This patch is by far the most complex in the series. It adds a new syscall > paccept. This syscall differs from accept in that it adds (at the userlevel) > two additional parameters: > > - a signal mask > - a flags value > > The flags parameter can be used to set flag like SOCK_CLOEXEC. This is > imlpemented here as well. Some people argued that this is a property > which should be inherited from the file desriptor for the server but > this is against POSIX. Additionally, we really want the signal mask > parameter as well (similar to pselect, ppoll, etc). So an interface > change in inevitable. > > The flag value is the same as for socket and socketpair. I think > diverging here will only create confusion. Similar to the filesystem > interfaces where the use of the O_* constants differs, it is acceptable > here. > > The signal mask is handled as for pselect etc. The mask is temporarily > installed for the thread and removed before the call returns. I modeled > the code after pselect. If there is a problem it's likely also in > pselect. > > For architectures which use socketcall I maintained this interface > instead of adding a system call. The symmetry shouldn't be broken. > > The following test must be adjusted for architectures other than x86 and > x86-64 and in case the syscall numbers changed. > I have a bit of a mystery going on here. > ... > > +asmlinkage long sys_paccept(int fd, struct sockaddr __user *upeer_sockaddr, > + int __user *upeer_addrlen, > + const sigset_t __user *sigmask, > + size_t sigsetsize, int flags) > +{ > + sigset_t ksigmask, sigsaved; > + int ret; > + > + if (sigmask) { > + /* XXX: Don't preclude handling different sized sigset_t's. */ > + if (sigsetsize != sizeof(sigset_t)) > + return -EINVAL; > + if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask))) > + return -EFAULT; > + > + sigdelsetmask(&ksigmask, sigmask(SIGKILL)|sigmask(SIGSTOP)); > + sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved); > + } > + > + ret = do_accept(fd, upeer_sockaddr, upeer_addrlen, flags); > + > + if (ret < 0 && signal_pending(current)) { > + /* > + * Don't restore the signal mask yet. Let do_signal() deliver > + * the signal on the way back to userspace, before the signal > + * mask is restored. > + */ > + if (sigmask) { > + memcpy(¤t->saved_sigmask, &sigsaved, > + sizeof(sigsaved)); > + set_thread_flag(TIF_RESTORE_SIGMASK); > + } > + } else if (sigmask) > + sigprocmask(SIG_SETMASK, &sigsaved, NULL); > + > + return ret; > +} Some architectures (including x86) do not implement TIF_RESTORE_SIGMASK. Ah, you must have prepared the patches against something prehistoric like 2.6.25. Please prefer to prepare 2.6.x patches against the 2.6.x tree, not the 2.6.x-1 tree? Whatever you're trying to do here, we'll need to find a non-arch-specific way of doing it.