From mboxrd@z Thu Jan 1 00:00:00 1970 Received: with ECARTIS (v1.0.0; list linux-mips); Fri, 26 Jun 2009 02:49:57 +0200 (CEST) Received: from h5.dl5rb.org.uk ([81.2.74.5]:55007 "EHLO h5.dl5rb.org.uk" rhost-flags-OK-OK-OK-OK) by ftp.linux-mips.org with ESMTP id S1493074AbZFZAtt (ORCPT ); Fri, 26 Jun 2009 02:49:49 +0200 Received: from h5.dl5rb.org.uk (localhost.localdomain [127.0.0.1]) by h5.dl5rb.org.uk (8.14.3/8.14.3) with ESMTP id n5Q0jhxI019761; Fri, 26 Jun 2009 01:45:44 +0100 Received: (from ralf@localhost) by h5.dl5rb.org.uk (8.14.3/8.14.3/Submit) id n5Q0jR42019741; Fri, 26 Jun 2009 01:45:27 +0100 Date: Fri, 26 Jun 2009 01:45:27 +0100 From: Ralf Baechle To: Kaz Kylheku Cc: "Kevin D. Kissell" , linux-mips@linux-mips.org Subject: Re: Silly 100% CPU behavior on a SIG_IGN-ored SIGBUS. Message-ID: <20090626004527.GA3235@linux-mips.org> References: <20090625134511.GC10661@linux-mips.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Return-Path: X-Envelope-To: <"|/home/ecartis/ecartis -s linux-mips"> (uid 0) X-Orcpt: rfc822;linux-mips@linux-mips.org Original-Recipient: rfc822;linux-mips@linux-mips.org X-archive-position: 23503 X-ecartis-version: Ecartis v1.0.0 Sender: linux-mips-bounce@linux-mips.org Errors-to: linux-mips-bounce@linux-mips.org X-original-sender: ralf@linux-mips.org Precedence: bulk X-list: linux-mips On Thu, Jun 25, 2009 at 09:00:19AM -0700, Kaz Kylheku wrote: > Ralf wrote: > > I found this in IRIX 6.5 documentation: > > > > Caution: Signals raised by the instruction stream, SIGILL, > > SIGEMT, SIGBUS, and SIGSEGV, will cause infinite loops > > if their handler returns, or the action is set to SIG_IGN. > > The Single Unix Specification (Issue 6) marks the behavior > explicitly undefined. I should have mentioned that above mentioned paragraph of IRIX documentation was in the section on implmentation specific behaviour. > Bookmark this: http://www.opengroup.org/onlinepubs/009695399 > > Not the latest set of documents, but that can be regarded > as a virtue. :) > > Under pthread_sigmask and sigprocmask, for blocking: > > If any of the SIGFPE, SIGILL, SIGSEGV, or SIGBUS > signals are generated while they are blocked, > the result is undefined, unless the signal > was generated by the kill() function, the > sigqueue() function, or the raise() function. > > Under ``2.4 Signal Concepts'', for SIG_IGN: > > SIG_IGN > > Ignore signal. > > Delivery of the signal shall have no effect on > the process. The behavior of a process is undefined > after it ignores a SIGFPE, SIGILL, SIGSEGV, > or SIGBUS signal that was not generated by kill(), > sigqueue(), or raise(). > > So, as I suspected, there are in fact no requirements > from the applicable spec. Infinite looping or > stopping the process anyway are conforming responses, > as is rebooting or halting the machine with a > ``panic'' message. I'd not go quite as far as that but execve("/usr/bin/nethack") certainly would be acceptable. Ralf