From owner-freebsd-net@freebsd.org Fri Dec 23 01:29:44 2016 Return-Path: Delivered-To: freebsd-net@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 A9DBEC8C6E5 for ; Fri, 23 Dec 2016 01:29:44 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: from mail-wm0-x244.google.com (mail-wm0-x244.google.com [IPv6:2a00:1450:400c:c09::244]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 3A78E16A1; Fri, 23 Dec 2016 01:29:44 +0000 (UTC) (envelope-from rizzo.unipi@gmail.com) Received: by mail-wm0-x244.google.com with SMTP id u144so39035497wmu.0; Thu, 22 Dec 2016 17:29:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=mime-version:sender:in-reply-to:references:from:date:message-id :subject:to:cc; bh=nDuHEaIV74qZU2BgvB+YNowgejsNeQ5PL2dnWw3n3QE=; b=TJW24ed0BxBaWVCYoN5rS1iq4ukAfDCDVjmkYiToyJwSy0eid4bpi3sNNYCTd3dDRG PQuj5B7MPiTpuMBwYWa2tMJClr7rdlgB9WXpqv4DKwvhJvqvCkfDrJkHAzALN60Hj64X 9qTyHlfTZ1olCBqMFi6+LGFnrhx7Af8VbARQ9lsQLP2AL5Osg29MC+fO21u6V88ql4N9 uA3pX8pOn0OhpWFYBHMnxpLfnVtjDpX2ggyK0cpkPKrfDVyugid8PR8YPMIMEd/s1Opr qTK46qnH9Se+eb5L2eelTjWYkOoAFxZPzBCB22zISkUEE7yxnEhjz/LcwXfvgeyrwE9D HCJg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:sender:in-reply-to:references:from :date:message-id:subject:to:cc; bh=nDuHEaIV74qZU2BgvB+YNowgejsNeQ5PL2dnWw3n3QE=; b=G+xH/iBmI9bcTL933HKY82QVQK8OQtqQBPo0lgpLrS3dVt/zB3oIZKdSBmpEJuMcDK gtfDE9grtfjWSlZHld9R8V0tsI0d/8TWYYtPPRjJ4XvIicCte7iabFyqIFu0Ej29T6Ku eRKsI2aCZ7GnyWILl7Uqruf09oX4VQK3i27xUzEWdDPqMZp7GyGFyvpDfpn15vURlSXW 20ksFOKriSOU45Nd/FJaFJgdGx6HXRDdhTv538H8oYooBxLbVw+kiY3S1dfuUcDR0jMq nIZYKfdsUySeEUuqg1eLO9rvYdGwxcwslcdjoHScg3WZpAJjsY1moqADy3OKxR6Pc7an SkCg== X-Gm-Message-State: AIkVDXINfCPD5lp2sGHh6pQkY+hWJ181oGJQa/HCvhnbUPTj2XfFcJfuc+oVVE1wGCCxQBXofQAoJtYY2CfaaQ== X-Received: by 10.28.125.136 with SMTP id y130mr13936163wmc.112.1482456582387; Thu, 22 Dec 2016 17:29:42 -0800 (PST) MIME-Version: 1.0 Sender: rizzo.unipi@gmail.com Received: by 10.28.196.207 with HTTP; Thu, 22 Dec 2016 17:29:41 -0800 (PST) In-Reply-To: References: <20161217222812.GA4979@ox> From: Luigi Rizzo Date: Thu, 22 Dec 2016 17:29:41 -0800 X-Google-Sender-Auth: uKYPkXdTKK4lEo3eSO6zfTOHnXc Message-ID: Subject: Re: cxgbe's native netmap support broken since r307394 To: Adrian Chadd Cc: Vincenzo Maffione , Navdeep Parhar , "freebsd-net@freebsd.org" , Luigi Rizzo , Giuseppe Lettieri Content-Type: text/plain; charset=UTF-8 X-BeenThere: freebsd-net@freebsd.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: Networking and TCP/IP with FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 23 Dec 2016 01:29:44 -0000 sure go ahead and thank you! On Thu, Dec 22, 2016 at 5:15 PM, Adrian Chadd wrote: > ok, does anyone mind if I commit it as-is? > > > -a > > > On 21 December 2016 at 13:37, Vincenzo Maffione wrote: >> Hi Luigi, >> I attached a minimal change containing two fixes: >> >> - change IFNET_WLOCK into IFNET_RLOCK, to fix the cxgbe issue related >> to this thread >> - use the proper locking functions for the "worker_lock", unrelated >> but needed to avoid the O.S. to trap because of a mismatch between >> MTX_SPIN and MTX_DEF. >> >> Cheers, >> Vincenzo >> >> 2016-12-21 20:30 GMT+01:00 Luigi Rizzo : >>> On Wed, Dec 21, 2016 at 11:15 AM, Vincenzo Maffione >>> wrote: >>>> Hi, >>>> There is no commit related to that in the FreeBSD svn or git. >>>> >>>> The fix has been published to the github netmap repository here >>>> (branch master): https://github.com/luigirizzo/netmap >>>> >>>> What we should do is to import all the recent updates from the github >>>> into HEAD. I can prepare a patch for HEAD, if you wish. Just let me >>>> know. >>> >>> I just checked and the diff between FreeBSD head and netmap head >>> in github is almost 3k lines due to a lot of recent refactoring. >>> So, if there is an easy way to extract just the locking change that would >>> be preferable as an interim solution. >>> >>> cheers >>> luigi >>> >>>> >>>> Cheers, >>>> Vincenzo >>>> >>>> >>>> 2016-12-20 21:45 GMT+01:00 Adrian Chadd : >>>>> hi, >>>>> >>>>> What's the commit? We should get it into -HEAD asap. >>>>> >>>>> >>>>> -adrian >>>>> >>>>> >>>>> On 20 December 2016 at 01:25, Vincenzo Maffione wrote: >>>>>> Ok, applied to the netmap github repo. >>>>>> This fix will be published when Luigi does the next commit on FreeBSD. >>>>>> >>>>>> Cheers, >>>>>> Vincenzo >>>>>> >>>>>> 2016-12-19 20:05 GMT+01:00 Navdeep Parhar : >>>>>>> IFNET_RLOCK will work, thanks. >>>>>>> >>>>>>> Navdeep >>>>>>> >>>>>>> On Mon, Dec 19, 2016 at 3:21 AM, Vincenzo Maffione wrote: >>>>>>>> Hi Navdeep, >>>>>>>> >>>>>>>> Indeed, we have reviewed the code, and we think it is ok to >>>>>>>> implement nm_os_ifnet_lock() with IFNET_RLOCK(), instead of using >>>>>>>> IFNET_WLOCK(). >>>>>>>> Since IFNET_RLOCK() results into sx_slock(), this should fix the issue. >>>>>>>> >>>>>>>> On FreeBSD, this locking is needed to protect a flag read by nm_iszombie(). >>>>>>>> However, on Linux the same lock is also needed to protect the call to >>>>>>>> the nm_hw_register() callback, so we prefer to have an "unified" >>>>>>>> locking scheme, i.e. always calling nm_hw_register under the lock. >>>>>>>> >>>>>>>> Does this make sense to you? Would it be easy for you to make a quick >>>>>>>> test by replacing IFNET_WLOCK with IFNET_RLOCK? >>>>>>>> >>>>>>>> Thanks, >>>>>>>> Vincenzo >>>>>>>> >>>>>>>> 2016-12-17 23:28 GMT+01:00 Navdeep Parhar : >>>>>>>>> Luigi, Vincenzo, >>>>>>>>> >>>>>>>>> The last major update to netmap (r307394 and followups) broke cxgbe's >>>>>>>>> native netmap support. The problem is that netmap_hw_reg now holds an >>>>>>>>> rw_lock around the driver's netmap_on/off routines. It has always been >>>>>>>>> safe for the driver to sleep during these operations but now it panics >>>>>>>>> instead. >>>>>>>>> >>>>>>>>> Why is IFNET_WLOCK needed here? It seems like a regression to disallow >>>>>>>>> sleep on the control path. >>>>>>>>> >>>>>>>>> Regards, >>>>>>>>> Navdeep >>>>>>>>> >>>>>>>>> begin_synchronized_op with the following non-sleepable locks held: >>>>>>>>> exclusive rw ifnet_rw (ifnet_rw) r = 0 (0xffffffff8271d680) locked @ >>>>>>>>> /root/ws/head/sys/dev/netmap/netmap_freebsd.c:95 >>>>>>>>> stack backtrace: >>>>>>>>> #0 0xffffffff810837a5 at witness_debugger+0xe5 >>>>>>>>> #1 0xffffffff81084d88 at witness_warn+0x3b8 >>>>>>>>> #2 0xffffffff83ef2bcc at begin_synchronized_op+0x6c >>>>>>>>> #3 0xffffffff83f14beb at cxgbe_netmap_reg+0x5b >>>>>>>>> #4 0xffffffff809846f1 at netmap_hw_reg+0x81 >>>>>>>>> #5 0xffffffff809806de at netmap_do_regif+0x19e >>>>>>>>> #6 0xffffffff8098121d at netmap_ioctl+0x7ad >>>>>>>>> #7 0xffffffff8098682f at freebsd_netmap_ioctl+0x5f >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> -- >>>>>>>> Vincenzo Maffione >>>>>>>> _______________________________________________ >>>>>>>> freebsd-net@freebsd.org mailing list >>>>>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net >>>>>>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >>>>>> >>>>>> >>>>>> >>>>>> -- >>>>>> Vincenzo Maffione >>>>>> _______________________________________________ >>>>>> freebsd-net@freebsd.org mailing list >>>>>> https://lists.freebsd.org/mailman/listinfo/freebsd-net >>>>>> To unsubscribe, send any mail to "freebsd-net-unsubscribe@freebsd.org" >>>> >>>> >>>> >>>> -- >>>> Vincenzo Maffione >>> >>> >>> >>> -- >>> -----------------------------------------+------------------------------- >>> Prof. Luigi RIZZO, rizzo@iet.unipi.it . Dip. di Ing. dell'Informazione >>> http://www.iet.unipi.it/~luigi/ . Universita` di Pisa >>> TEL +39-050-2217533 . via Diotisalvi 2 >>> Mobile +39-338-6809875 . 56122 PISA (Italy) >>> -----------------------------------------+------------------------------- >> >> >> >> -- >> Vincenzo Maffione -- -----------------------------------------+------------------------------- Prof. Luigi RIZZO, rizzo@iet.unipi.it . Dip. di Ing. dell'Informazione http://www.iet.unipi.it/~luigi/ . Universita` di Pisa TEL +39-050-2217533 . via Diotisalvi 2 Mobile +39-338-6809875 . 56122 PISA (Italy) -----------------------------------------+-------------------------------