From owner-svn-src-head@freebsd.org Tue Nov 28 18:02:02 2017 Return-Path: Delivered-To: svn-src-head@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id BCE43DE8ED3; Tue, 28 Nov 2017 18:02:02 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from mail.baldwin.cx (bigwig.baldwin.cx [96.47.65.170]) (using TLSv1 with cipher DHE-RSA-CAMELLIA256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 9A0FA713B5; Tue, 28 Nov 2017 18:02:02 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from ralph.baldwin.cx (c-73-231-226-104.hsd1.ca.comcast.net [73.231.226.104]) by mail.baldwin.cx (Postfix) with ESMTPSA id F271F10A8BC; Tue, 28 Nov 2017 13:01:55 -0500 (EST) From: John Baldwin To: Nathan Whitehorn Cc: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: Re: svn commit: r326218 - head/sys/kern Date: Mon, 27 Nov 2017 16:00:59 -0800 Message-ID: <14058479.lc6xlYgyBM@ralph.baldwin.cx> User-Agent: KMail/4.14.10 (FreeBSD/11.1-STABLE; KDE/4.14.30; amd64; ; ) In-Reply-To: <3fc45d5f-22b9-0562-278b-c515e36f48e7@freebsd.org> References: <201711252341.vAPNf5Qx001464@repo.freebsd.org> <14322447.103fKFTi3y@ralph.baldwin.cx> <3fc45d5f-22b9-0562-278b-c515e36f48e7@freebsd.org> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.4.3 (mail.baldwin.cx); Tue, 28 Nov 2017 13:01:56 -0500 (EST) X-Virus-Scanned: clamav-milter 0.99.2 at mail.baldwin.cx X-Virus-Status: Clean X-BeenThere: svn-src-head@freebsd.org X-Mailman-Version: 2.1.25 Precedence: list List-Id: SVN commit messages for the src tree for head/-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 28 Nov 2017 18:02:02 -0000 On Monday, November 27, 2017 02:04:59 PM Nathan Whitehorn wrote: > Unfortunately, it's unfixable on ppc64. Apologies for breaking dtrace! > Would you like me to remove the KASSERT() here? I'm happy to do that in > a few hours (unless you beat me to it first) -- although I do think that > explicitly checking for CPU_ABSENT is a much better behavior in client > code than checking the return value of pcpu_find(). It sounds like the dtrace change is actually fine as-is. At the very least fix the style of the kassert for now I guess. In general though I think our kernel basically depends on NULL faulting and in the past I recall Bruce has usually advocated for depending on the page fault from NULL rather than adding explicit assertions just for 'foo != NULL'. >From some discussion on IRC after this e-mail though it seems that NULL might not be entirely unfixable on powerpc64? -- John Baldwin