From owner-freebsd-acpi@FreeBSD.ORG Mon Sep 24 17:16:14 2007 Return-Path: Delivered-To: freebsd-acpi@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A647516A419; Mon, 24 Sep 2007 17:16:14 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from speedfactory.net (mail6.speedfactory.net [66.23.216.219]) by mx1.freebsd.org (Postfix) with ESMTP id 6830113C465; Mon, 24 Sep 2007 17:16:14 +0000 (UTC) (envelope-from jhb@freebsd.org) Received: from server.baldwin.cx (unverified [66.23.211.162]) by speedfactory.net (SurgeMail 3.8p) with ESMTP id 211151065-1834499 for multiple; Mon, 24 Sep 2007 13:14:35 -0400 Received: from localhost.corp.yahoo.com (john@localhost [127.0.0.1]) (authenticated bits=0) by server.baldwin.cx (8.13.8/8.13.8) with ESMTP id l8OHFsUL099059; Mon, 24 Sep 2007 13:15:54 -0400 (EDT) (envelope-from jhb@freebsd.org) From: John Baldwin To: Nate Lawson Date: Mon, 24 Sep 2007 13:15:52 -0400 User-Agent: KMail/1.9.6 References: <200709181516.11207.jkim@FreeBSD.org> <200709241259.01518.jkim@FreeBSD.org> <46F7EDD6.4010508@root.org> In-Reply-To: <46F7EDD6.4010508@root.org> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200709241315.53665.jhb@freebsd.org> X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (server.baldwin.cx [127.0.0.1]); Mon, 24 Sep 2007 13:15:54 -0400 (EDT) X-Virus-Scanned: ClamAV 0.88.3/4378/Mon Sep 24 08:25:35 2007 on server.baldwin.cx X-Virus-Status: Clean X-Spam-Status: No, score=-4.4 required=4.2 tests=ALL_TRUSTED,AWL,BAYES_00 autolearn=ham version=3.1.3 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on server.baldwin.cx Cc: freebsd-acpi@freebsd.org, freebsd-current@freebsd.org, Jung-uk Kim Subject: Re: [PATCH] OsdSynch.c modernization X-BeenThere: freebsd-acpi@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: ACPI and power management development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 Sep 2007 17:16:14 -0000 On Monday 24 September 2007 01:03:18 pm Nate Lawson wrote: > Jung-uk Kim wrote: > > On Monday 24 September 2007 12:28 pm, John Baldwin wrote: > >> On Monday 24 September 2007 12:11:07 pm Nate Lawson wrote: > >>> John Baldwin wrote: > >>>> 2007/9/22, Jung-uk Kim : > >>>>> I thought exactly the same when I started rewriting it (almost > >>>>> half year ago!). I have tried all of the above, spent > >>>>> numerous sleepless nights, and miserably failed. :-( > >>>>> > >>>>> Spin mutex is too restrictive (e.g., it cannot be used with > >>>>> other locks gracefully). critical_enter() causes: > >>>>> > >>>>> panic: blockable sleep lock (sleep mutex) 32 @ > >>>>> /usr/src/sys/vm/uma_core.c:1830 cpuid = 0 > >>>>> KDB: enter: panic > >>>>> [thread pid 21 tid 100013 ] > >>>>> Stopped at kdb_enter+0x32: leave > >>>> However, disabling interrupts while you block on other locks is > >>>> just as > >> bad, > >> > >>>> we just don't assert for it. Better would be to fix ACPI-CA to > >>>> not try to malloc() while holding a spin lock. You should be > >>>> able to see where it is doing that via the stack trace. If the > >>>> malloc is using M_NOWAIT you will > >> be > >> > >>>> far better off using a plain mutex and just not disabling > >>>> interrupts. > >>> For 7.0, we're going with what we have (sx locks) since it's > >>> well-tested and not wrong, maybe just less than optimal. > >>> Remember that acpi locks are acquired a few dozen times every 10 > >>> seconds or so, so this is not at risk of being a performance > >>> issue. > >> Disabling interrupts and then calling malloc() is wrong however. > > > > Understood. As I said earlier, I really like to fix it correctly. > > > > > > However, the problem is that there are so many different BIOSes out > > there, taking so different code paths. Whenever I thought it's > > fixed, someone says 'you broke my laptop' or 'FreeBSD is bad because > > it doesn't boot on my laptop but Linux and Windows boot fine'. :-( > > > > > > (At least on my laptop) I found the malloc() was called from our code, > > i.e., AcpiOsExecute() from OsdSched.c. I'll try something shortly > > cause I was going to rewrite the file anyway. > > Yep, that's because we need a task structure that's different for each > call and acpi-ca doesn't like the "pending" argument (see > OsdSchedule.c). One fix for this is to just use a hack and cast the fn > to discard the extra arg. Not sure this would work. > > I thought malloc(...NOWAIT) *could* be called with a mutex held? It > just checks a list and returns NULL if empty, right? But not a spin mutex.... -- John Baldwin