From owner-freebsd-testing@FreeBSD.ORG Thu Mar 6 15:32:50 2014 Return-Path: Delivered-To: freebsd-testing@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 911ACE7C for ; Thu, 6 Mar 2014 15:32:50 +0000 (UTC) Received: from relay02.pair.com (relay02.pair.com [209.68.5.16]) by mx1.freebsd.org (Postfix) with SMTP id 4655D2FF for ; Thu, 6 Mar 2014 15:32:50 +0000 (UTC) Received: (qmail 19420 invoked from network); 6 Mar 2014 15:32:48 -0000 Received: from 87.58.146.155 (HELO x2.osted.lan) (87.58.146.155) by relay02.pair.com with SMTP; 6 Mar 2014 15:32:48 -0000 X-pair-Authenticated: 87.58.146.155 Received: from x2.osted.lan (localhost [127.0.0.1]) by x2.osted.lan (8.14.5/8.14.5) with ESMTP id s26FWlCg023995; Thu, 6 Mar 2014 16:32:47 +0100 (CET) (envelope-from pho@x2.osted.lan) Received: (from pho@localhost) by x2.osted.lan (8.14.5/8.14.5/Submit) id s26FWlRs023994; Thu, 6 Mar 2014 16:32:47 +0100 (CET) (envelope-from pho) Date: Thu, 6 Mar 2014 16:32:47 +0100 From: Peter Holm To: Eitan Adler Subject: Re: Test scenario for sysctl kern.maxfiles Message-ID: <20140306153247.GA22830@x2.osted.lan> References: <20140305085806.GA70478@x2.osted.lan> <20140306112322.GA10664@x2.osted.lan> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.21 (2010-09-15) Cc: "freebsd-testing@freebsd.org" X-BeenThere: freebsd-testing@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Testing on FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 06 Mar 2014 15:32:50 -0000 On Thu, Mar 06, 2014 at 09:15:58AM -0500, Eitan Adler wrote: > On 6 March 2014 06:23, Peter Holm wrote: > > On Wed, Mar 05, 2014 at 10:08:49AM -0700, Alan Somers wrote: > >> On Wed, Mar 5, 2014 at 1:58 AM, Peter Holm wrote: > >> > Here's an attempt to verify that increasing kern.maxfiles works as > >> > expected. > >> > > >> > http://people.freebsd.org/~pho/kern_descrip_test-v3.diff > >> > -- > >> > Peter > >> > >> 1) done should be of type "static volatile sig_atomic_t", not int, > >> because it's set by signal handlers. > >> > > > > Yes, that is nicer (I learned something new today :-). But the use > > here works because there is a call to usleep(3) after each test, > > forcing the compiler to reload the "done" variable. > > That isn't what sig_atomic_t is trying to prevent. It is an ""integer > type of an object that can be accessed as an atomic entity, even in > the presence of asynchronous interrupts."". In particular, on some > machines it would be possible for the signal handler to observe a > half-updated "int" type variable. > > On i386 sig_atomic_t happens to be an "int". On amd64 it happens to > be a long. This is not contractual. > I only just realize that the ATF test programs are threaded. Anyway it seems to be a good practice to always use "static volatile sig_atomic_t" for signal handler variables. -- Peter