From owner-freebsd-arch@FreeBSD.ORG Thu Nov 13 09:42:55 2014 Return-Path: Delivered-To: freebsd-arch@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 7FB581D8; Thu, 13 Nov 2014 09:42:55 +0000 (UTC) Received: from elvis.mu.org (elvis.mu.org [IPv6:2001:470:1f05:b76::196]) by mx1.freebsd.org (Postfix) with ESMTP id 66EA2D6F; Thu, 13 Nov 2014 09:42:55 +0000 (UTC) Received: from AlfredMacbookAir.local (c-76-21-10-192.hsd1.ca.comcast.net [76.21.10.192]) by elvis.mu.org (Postfix) with ESMTPSA id 33212341F84E; Thu, 13 Nov 2014 01:42:55 -0800 (PST) Message-ID: <54647D1E.9010904@freebsd.org> Date: Thu, 13 Nov 2014 01:42:54 -0800 From: Alfred Perlstein Organization: FreeBSD User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.10; rv:24.0) Gecko/20100101 Thunderbird/24.6.0 MIME-Version: 1.0 To: Adrian Chadd Subject: Re: Questions about locking; turnstiles and sleeping threads References: <20141112212613.21037929@kan> <546472DA.3080006@freebsd.org> <5464764E.9080308@freebsd.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: Hans Petter Selasky , "freebsd-arch@freebsd.org" X-BeenThere: freebsd-arch@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Discussion related to FreeBSD architecture List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 13 Nov 2014 09:42:55 -0000 OK that makes more sense. I've cc'd Hans for the usb issue. On 11/13/14, 1:38 AM, Adrian Chadd wrote: > It looks like the initial firings are because the check I put in > didn't check to see if it's MPSAFE. > > eg: > > ip6_input -> tcp6_input -> tcp_input -> tcp_do_segment -> > tcp_timer_active -> callout_stop_safe; called with tcpinp held. > closefp() -> closef() -> fdrop -> soclose() -> sofree() -> > tcp_usr_detach() -> tcp_discardcb() -> callout_stop_safe() with the > tcpinp and tcp locks held. > ioctl -> sys_ioctl-> devfs_ioctl_f -> acpi_ackSleepState -> > callout_stop_safe; with ACPI global lock held; > suspend path -> hdaa_suspend -> callout_stop_safe() with HDA driver mutex held > > So we can't just put the simple witness check from _sleep() in > _callout_stop_safe(), it looks like it's mis-firing on MPSAFE callouts > (which the tcp timers all are) and that won't go via the sleepq. > It looks like the acpi callout is also mpsafe, as well as the HDA jack callout. > > However, I did pick up this: > > detach path -> usbd_transfer_drain() -> usbd_transfer_stop() -> > ehci_device_intr_close() -> usbd_transfer_done() -> > callout_stop_safe() with USB HUB mutex held > > The usbd_transfer_done() callout is initialised with a mutex, but the > witness code should've detected it wasn't callout->c_lock and thus > warned. > > > > -adrian > > On 13 November 2014 01:13, Alfred Perlstein wrote: >> On 11/13/14, 1:09 AM, Adrian Chadd wrote: >>> On 13 November 2014 00:59, Alfred Perlstein wrote: >>>> On 11/12/14, 11:25 PM, Adrian Chadd wrote: >>>>> On 12 November 2014 19:48, Adrian Chadd wrote: >>>>>> kan pointed out that we should likely do a WITNESS_WARN() in the >>>>>> relevant spots in the callout code so we catch these before it >>>>>> happens. >>>>>> >>>>>> I'll see what we can add to -HEAD to be pro-active about it. >>>>> Amusingly, I tried adding it and it made my laptop turn to soup very >>>>> quickly - among other things, the TCP timer callouts are all setup >>>>> with non sleep locks held. >>>>> >>>> Howso? You only have to worry about callout_drain(), most other callout >>>> functions should be safe-ish.... >>> yeah, except for all the places where they drain the timer once >>> something happens so it doesn't fire. >>> >>> :) >> >> What is the backtrace...? >> >> > _______________________________________________ > freebsd-arch@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-arch > To unsubscribe, send any mail to "freebsd-arch-unsubscribe@freebsd.org" >