From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5C9E0C76194 for ; Thu, 25 Jul 2019 05:53:14 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3315321850 for ; Thu, 25 Jul 2019 05:53:14 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728592AbfGYFxK (ORCPT ); Thu, 25 Jul 2019 01:53:10 -0400 Received: from mail-qk1-f196.google.com ([209.85.222.196]:39616 "EHLO mail-qk1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727962AbfGYFxD (ORCPT ); Thu, 25 Jul 2019 01:53:03 -0400 Received: by mail-qk1-f196.google.com with SMTP id w190so35565244qkc.6 for ; Wed, 24 Jul 2019 22:53:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=JO71JAUQG8v5NWS9aFNJS8lKMgEFxdUfgocNmFAYG40=; b=dfZFGbaUmJ6E5SaLYe1+XOhcIj+QpsSPlluDSyE6qPSB09Beg7NppSyGJpsvWKeZPi rcucWlVFyiAURbiV8AdR+vcgInJzlmpKKh0WCilnKSbYwP6mSZUuqAIPtLv0Ed9doT2R n0AtwhOEcaEFU02UDpQ2NrHrp9PPPnVWMmNaF+c/tkShkNHPUq/2/da5+vC40ENzzNET JhrVuRbKdgvDmvtYrPqQUNyG0vsBML2Ms9Sc+3I53lYZ3yzQbyrL1x7rvIcihhO/JXcU teJ6SgzRlQizx3npyf+FdMavt4xv86XhdvLjZUSs1tknQ/FV4+ioWQKDFJyXucmUpT7S WwOg== X-Gm-Message-State: APjAAAUOIKXg7R1H90d2jHqatd6GldscZmdwI6rxawQEQJXGiWHqoWFx bjc7xXnlHk5Rsv/x72ni96MhQQ== X-Google-Smtp-Source: APXvYqzSdjCF8KfvPtVJQN/Fq3QA2lZs756ix2x+aw9grYNxhN50Gd3YATAXPDQIBe87A663Tz88jg== X-Received: by 2002:a37:91c2:: with SMTP id t185mr56548270qkd.193.1564033982538; Wed, 24 Jul 2019 22:53:02 -0700 (PDT) Received: from redhat.com (bzq-79-181-91-42.red.bezeqint.net. [79.181.91.42]) by smtp.gmail.com with ESMTPSA id p3sm33849924qta.12.2019.07.24.22.52.55 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 22:53:01 -0700 (PDT) Date: Thu, 25 Jul 2019 01:52:53 -0400 From: "Michael S. Tsirkin" To: Jason Wang Cc: syzbot , aarcange@redhat.com, akpm@linux-foundation.org, christian@brauner.io, davem@davemloft.net, ebiederm@xmission.com, elena.reshetova@intel.com, guro@fb.com, hch@infradead.org, james.bottomley@hansenpartnership.com, jglisse@redhat.com, keescook@chromium.org, ldv@altlinux.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-parisc@vger.kernel.org, luto@amacapital.net, mhocko@suse.com, mingo@kernel.org, namit@vmware.com, peterz@infradead.org, syzkaller-bugs@googlegroups.com, viro@zeniv.linux.org.uk, wad@chromium.org Subject: Re: WARNING in __mmdrop Message-ID: <20190725012149-mutt-send-email-mst@kernel.org> References: <20190722040230-mutt-send-email-mst@kernel.org> <4bd2ff78-6871-55f2-44dc-0982ffef3337@redhat.com> <20190723010019-mutt-send-email-mst@kernel.org> <20190723032024-mutt-send-email-mst@kernel.org> <1d14de4d-0133-1614-9f64-3ded381de04e@redhat.com> <20190723035725-mutt-send-email-mst@kernel.org> <3f4178f1-0d71-e032-0f1f-802428ceca59@redhat.com> <20190723051828-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: linux-parisc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-parisc@vger.kernel.org On Tue, Jul 23, 2019 at 09:31:35PM +0800, Jason Wang wrote: > > On 2019/7/23 下午5:26, Michael S. Tsirkin wrote: > > On Tue, Jul 23, 2019 at 04:49:01PM +0800, Jason Wang wrote: > > > On 2019/7/23 下午4:10, Michael S. Tsirkin wrote: > > > > On Tue, Jul 23, 2019 at 03:53:06PM +0800, Jason Wang wrote: > > > > > On 2019/7/23 下午3:23, Michael S. Tsirkin wrote: > > > > > > > > Really let's just use kfree_rcu. It's way cleaner: fire and forget. > > > > > > > Looks not, you need rate limit the fire as you've figured out? > > > > > > See the discussion that followed. Basically no, it's good enough > > > > > > already and is only going to be better. > > > > > > > > > > > > > And in fact, > > > > > > > the synchronization is not even needed, does it help if I leave a comment to > > > > > > > explain? > > > > > > Let's try to figure it out in the mail first. I'm pretty sure the > > > > > > current logic is wrong. > > > > > Here is what the code what to achieve: > > > > > > > > > > - The map was protected by RCU > > > > > > > > > > - Writers are: MMU notifier invalidation callbacks, file operations (ioctls > > > > > etc), meta_prefetch (datapath) > > > > > > > > > > - Readers are: memory accessor > > > > > > > > > > Writer are synchronized through mmu_lock. RCU is used to synchronized > > > > > between writers and readers. > > > > > > > > > > The synchronize_rcu() in vhost_reset_vq_maps() was used to synchronized it > > > > > with readers (memory accessors) in the path of file operations. But in this > > > > > case, vq->mutex was already held, this means it has been serialized with > > > > > memory accessor. That's why I think it could be removed safely. > > > > > > > > > > Anything I miss here? > > > > > > > > > So invalidate callbacks need to reset the map, and they do > > > > not have vq mutex. How can they do this and free > > > > the map safely? They need synchronize_rcu or kfree_rcu right? > > > Invalidation callbacks need but file operations (e.g ioctl) not. > > > > > > > > > > And I worry somewhat that synchronize_rcu in an MMU notifier > > > > is a problem, MMU notifiers are supposed to be quick: > > > Looks not, since it can allow to be blocked and lots of driver depends on > > > this. (E.g mmu_notifier_range_blockable()). > > Right, they can block. So why don't we take a VQ mutex and be > > done with it then? No RCU tricks. > > > This is how I want to go with RFC and V1. But I end up with deadlock between > vq locks and some MM internal locks. So I decide to use RCU which is 100% > under the control of vhost. > > Thanks And I guess the deadlock is because GUP is taking mmu locks which are taken on mmu notifier path, right? How about we add a seqlock and take that in invalidate callbacks? We can then drop the VQ lock before GUP, and take it again immediately after. something like if (!vq_meta_mapped(vq)) { vq_meta_setup(&uaddrs); mutex_unlock(vq->mutex) vq_meta_map(&uaddrs); mutex_lock(vq->mutex) /* recheck both sock->private_data and seqlock count. */ if changed - bail out } And also requires that VQ uaddrs is defined like this: - writers must have both vq mutex and dev mutex - readers must have either vq mutex or dev mutex That's a big change though. For now, how about switching to a per-vq SRCU? That is only a little bit more expensive than RCU, and we can use synchronize_srcu_expedited. -- MST From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-0.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A9918C7618B for ; Thu, 25 Jul 2019 05:53:17 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 7A5C921850 for ; Thu, 25 Jul 2019 05:53:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="l29quaNy" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7A5C921850 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=1vyRLN4sDRi7OwQc/8zgrBtTH5x2UH+EKq/ByYkMoKA=; b=l29quaNy1Z7KTZ cvS+Wyl2ejML4nrkpnUWvKQ8OwwngtfwdVn0fXCjKwy1gQzVCHm+cBy3TwwSffZ6EPEdLzprDFKWs iSXa6MuskyDoESnc7pXmuOgflChtsTzKBHK7NG69UkeiK5pLze/LN9ZSZO9p4tBr3JuTK9UIx8b2Y ttbh9i/IJI3gTPbDtkCl3YUMVfM9JhV6kYW2nz7rZUKfioJIksGaW4gDXC0jn7BfrB4efuru4YqFS D4Xqspo2pFxZwKo0Y8HoWpUGozv/PDlBKWT+7joxpzM9agcF1rGFbtQXJdGAkbi612SD9BY+K5IJ9 xD6sIPvWx03ntRaQdb2Q==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92 #3 (Red Hat Linux)) id 1hqWgd-0000Iv-IO; Thu, 25 Jul 2019 05:53:07 +0000 Received: from mail-qk1-f195.google.com ([209.85.222.195]) by bombadil.infradead.org with esmtps (Exim 4.92 #3 (Red Hat Linux)) id 1hqWga-0000IW-NF for linux-arm-kernel@lists.infradead.org; Thu, 25 Jul 2019 05:53:06 +0000 Received: by mail-qk1-f195.google.com with SMTP id d15so35561861qkl.4 for ; Wed, 24 Jul 2019 22:53:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:content-transfer-encoding :in-reply-to; bh=JO71JAUQG8v5NWS9aFNJS8lKMgEFxdUfgocNmFAYG40=; b=GRRmeW8hlTE7VFIJl+LjDrj5/KY565dyMOyQa9rvaM1ANl5mDJgaCa/UcDkVNF45PH n6vNdSYIblgwT9iv7QKNUyQ7rmtLpGsNiwCkjV176vDdLc+wRANzwT9apPWoWLMiZz+R K5ybz5fXFJeB5mtULg0+KQ2Sh4H3uaXXjXlY4GkYmqlCLuRAI8PDsThRDUpBH0miOaPt ZU7rhBbqVhpEubavHMgw7YEbyxXD4l4CdaqwJPcFdTxehplC57XZArvGD/R+AmZLX5YG 1FfbAaRTlHlw0Bi/DNaW3HTzmioGNzUzSijZKRjO/UlffmA4a7njo/aClxBBmHLjPZcU nSfQ== X-Gm-Message-State: APjAAAWxmQcJrhB2mq7GqAQlu1Vl1aQTYDEL32kmG6fkf6VWIy+9M5ED dH4x268S80ox++N6vb0iKvCH4w== X-Google-Smtp-Source: APXvYqzSdjCF8KfvPtVJQN/Fq3QA2lZs756ix2x+aw9grYNxhN50Gd3YATAXPDQIBe87A663Tz88jg== X-Received: by 2002:a37:91c2:: with SMTP id t185mr56548270qkd.193.1564033982538; Wed, 24 Jul 2019 22:53:02 -0700 (PDT) Received: from redhat.com (bzq-79-181-91-42.red.bezeqint.net. [79.181.91.42]) by smtp.gmail.com with ESMTPSA id p3sm33849924qta.12.2019.07.24.22.52.55 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Wed, 24 Jul 2019 22:53:01 -0700 (PDT) Date: Thu, 25 Jul 2019 01:52:53 -0400 From: "Michael S. Tsirkin" To: Jason Wang Subject: Re: WARNING in __mmdrop Message-ID: <20190725012149-mutt-send-email-mst@kernel.org> References: <20190722040230-mutt-send-email-mst@kernel.org> <4bd2ff78-6871-55f2-44dc-0982ffef3337@redhat.com> <20190723010019-mutt-send-email-mst@kernel.org> <20190723032024-mutt-send-email-mst@kernel.org> <1d14de4d-0133-1614-9f64-3ded381de04e@redhat.com> <20190723035725-mutt-send-email-mst@kernel.org> <3f4178f1-0d71-e032-0f1f-802428ceca59@redhat.com> <20190723051828-mutt-send-email-mst@kernel.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20190724_225304_760973_7450B351 X-CRM114-Status: GOOD ( 25.05 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mhocko@suse.com, peterz@infradead.org, ldv@altlinux.org, james.bottomley@hansenpartnership.com, linux-mm@kvack.org, namit@vmware.com, mingo@kernel.org, elena.reshetova@intel.com, keescook@chromium.org, aarcange@redhat.com, davem@davemloft.net, hch@infradead.org, christian@brauner.io, syzbot , syzkaller-bugs@googlegroups.com, jglisse@redhat.com, viro@zeniv.linux.org.uk, linux-arm-kernel@lists.infradead.org, wad@chromium.org, linux-parisc@vger.kernel.org, linux-kernel@vger.kernel.org, luto@amacapital.net, ebiederm@xmission.com, akpm@linux-foundation.org, guro@fb.com Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: base64 Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org T24gVHVlLCBKdWwgMjMsIDIwMTkgYXQgMDk6MzE6MzVQTSArMDgwMCwgSmFzb24gV2FuZyB3cm90 ZToKPiAKPiBPbiAyMDE5LzcvMjMg5LiL5Y2INToyNiwgTWljaGFlbCBTLiBUc2lya2luIHdyb3Rl Ogo+ID4gT24gVHVlLCBKdWwgMjMsIDIwMTkgYXQgMDQ6NDk6MDFQTSArMDgwMCwgSmFzb24gV2Fu ZyB3cm90ZToKPiA+ID4gT24gMjAxOS83LzIzIOS4i+WNiDQ6MTAsIE1pY2hhZWwgUy4gVHNpcmtp biB3cm90ZToKPiA+ID4gPiBPbiBUdWUsIEp1bCAyMywgMjAxOSBhdCAwMzo1MzowNlBNICswODAw LCBKYXNvbiBXYW5nIHdyb3RlOgo+ID4gPiA+ID4gT24gMjAxOS83LzIzIOS4i+WNiDM6MjMsIE1p Y2hhZWwgUy4gVHNpcmtpbiB3cm90ZToKPiA+ID4gPiA+ID4gPiA+IFJlYWxseSBsZXQncyBqdXN0 IHVzZSBrZnJlZV9yY3UuIEl0J3Mgd2F5IGNsZWFuZXI6IGZpcmUgYW5kIGZvcmdldC4KPiA+ID4g PiA+ID4gPiBMb29rcyBub3QsIHlvdSBuZWVkIHJhdGUgbGltaXQgdGhlIGZpcmUgYXMgeW91J3Zl IGZpZ3VyZWQgb3V0Pwo+ID4gPiA+ID4gPiBTZWUgdGhlIGRpc2N1c3Npb24gdGhhdCBmb2xsb3dl ZC4gQmFzaWNhbGx5IG5vLCBpdCdzIGdvb2QgZW5vdWdoCj4gPiA+ID4gPiA+IGFscmVhZHkgYW5k IGlzIG9ubHkgZ29pbmcgdG8gYmUgYmV0dGVyLgo+ID4gPiA+ID4gPiAKPiA+ID4gPiA+ID4gPiBB bmQgaW4gZmFjdCwKPiA+ID4gPiA+ID4gPiB0aGUgc3luY2hyb25pemF0aW9uIGlzIG5vdCBldmVu IG5lZWRlZCwgZG9lcyBpdCBoZWxwIGlmIEkgbGVhdmUgYSBjb21tZW50IHRvCj4gPiA+ID4gPiA+ ID4gZXhwbGFpbj8KPiA+ID4gPiA+ID4gTGV0J3MgdHJ5IHRvIGZpZ3VyZSBpdCBvdXQgaW4gdGhl IG1haWwgZmlyc3QuIEknbSBwcmV0dHkgc3VyZSB0aGUKPiA+ID4gPiA+ID4gY3VycmVudCBsb2dp YyBpcyB3cm9uZy4KPiA+ID4gPiA+IEhlcmUgaXMgd2hhdCB0aGUgY29kZSB3aGF0IHRvIGFjaGll dmU6Cj4gPiA+ID4gPiAKPiA+ID4gPiA+IC0gVGhlIG1hcCB3YXMgcHJvdGVjdGVkIGJ5IFJDVQo+ ID4gPiA+ID4gCj4gPiA+ID4gPiAtIFdyaXRlcnMgYXJlOiBNTVUgbm90aWZpZXIgaW52YWxpZGF0 aW9uIGNhbGxiYWNrcywgZmlsZSBvcGVyYXRpb25zIChpb2N0bHMKPiA+ID4gPiA+IGV0YyksIG1l dGFfcHJlZmV0Y2ggKGRhdGFwYXRoKQo+ID4gPiA+ID4gCj4gPiA+ID4gPiAtIFJlYWRlcnMgYXJl OiBtZW1vcnkgYWNjZXNzb3IKPiA+ID4gPiA+IAo+ID4gPiA+ID4gV3JpdGVyIGFyZSBzeW5jaHJv bml6ZWQgdGhyb3VnaCBtbXVfbG9jay4gUkNVIGlzIHVzZWQgdG8gc3luY2hyb25pemVkCj4gPiA+ ID4gPiBiZXR3ZWVuIHdyaXRlcnMgYW5kIHJlYWRlcnMuCj4gPiA+ID4gPiAKPiA+ID4gPiA+IFRo ZSBzeW5jaHJvbml6ZV9yY3UoKSBpbiB2aG9zdF9yZXNldF92cV9tYXBzKCkgd2FzIHVzZWQgdG8g c3luY2hyb25pemVkIGl0Cj4gPiA+ID4gPiB3aXRoIHJlYWRlcnMgKG1lbW9yeSBhY2Nlc3NvcnMp IGluIHRoZSBwYXRoIG9mIGZpbGUgb3BlcmF0aW9ucy4gQnV0IGluIHRoaXMKPiA+ID4gPiA+IGNh c2UsIHZxLT5tdXRleCB3YXMgYWxyZWFkeSBoZWxkLCB0aGlzIG1lYW5zIGl0IGhhcyBiZWVuIHNl cmlhbGl6ZWQgd2l0aAo+ID4gPiA+ID4gbWVtb3J5IGFjY2Vzc29yLiBUaGF0J3Mgd2h5IEkgdGhp bmsgaXQgY291bGQgYmUgcmVtb3ZlZCBzYWZlbHkuCj4gPiA+ID4gPiAKPiA+ID4gPiA+IEFueXRo aW5nIEkgbWlzcyBoZXJlPwo+ID4gPiA+ID4gCj4gPiA+ID4gU28gaW52YWxpZGF0ZSBjYWxsYmFj a3MgbmVlZCB0byByZXNldCB0aGUgbWFwLCBhbmQgdGhleSBkbwo+ID4gPiA+IG5vdCBoYXZlIHZx IG11dGV4LiBIb3cgY2FuIHRoZXkgZG8gdGhpcyBhbmQgZnJlZQo+ID4gPiA+IHRoZSBtYXAgc2Fm ZWx5PyBUaGV5IG5lZWQgc3luY2hyb25pemVfcmN1IG9yIGtmcmVlX3JjdSByaWdodD8KPiA+ID4g SW52YWxpZGF0aW9uIGNhbGxiYWNrcyBuZWVkIGJ1dCBmaWxlIG9wZXJhdGlvbnMgKGUuZyBpb2N0 bCkgbm90Lgo+ID4gPiAKPiA+ID4gCj4gPiA+ID4gQW5kIEkgd29ycnkgc29tZXdoYXQgdGhhdCBz eW5jaHJvbml6ZV9yY3UgaW4gYW4gTU1VIG5vdGlmaWVyCj4gPiA+ID4gaXMgYSBwcm9ibGVtLCBN TVUgbm90aWZpZXJzIGFyZSBzdXBwb3NlZCB0byBiZSBxdWljazoKPiA+ID4gTG9va3Mgbm90LCBz aW5jZSBpdCBjYW4gYWxsb3cgdG8gYmUgYmxvY2tlZCBhbmQgbG90cyBvZiBkcml2ZXIgZGVwZW5k cyBvbgo+ID4gPiB0aGlzLiAoRS5nIG1tdV9ub3RpZmllcl9yYW5nZV9ibG9ja2FibGUoKSkuCj4g PiBSaWdodCwgdGhleSBjYW4gYmxvY2suIFNvIHdoeSBkb24ndCB3ZSB0YWtlIGEgVlEgbXV0ZXgg YW5kIGJlCj4gPiBkb25lIHdpdGggaXQgdGhlbj8gTm8gUkNVIHRyaWNrcy4KPiAKPiAKPiBUaGlz IGlzIGhvdyBJIHdhbnQgdG8gZ28gd2l0aCBSRkMgYW5kIFYxLiBCdXQgSSBlbmQgdXAgd2l0aCBk ZWFkbG9jayBiZXR3ZWVuCj4gdnEgbG9ja3MgYW5kIHNvbWUgTU0gaW50ZXJuYWwgbG9ja3MuIFNv IEkgZGVjaWRlIHRvIHVzZSBSQ1Ugd2hpY2ggaXMgMTAwJQo+IHVuZGVyIHRoZSBjb250cm9sIG9m IHZob3N0Lgo+IAo+IFRoYW5rcwoKQW5kIEkgZ3Vlc3MgdGhlIGRlYWRsb2NrIGlzIGJlY2F1c2Ug R1VQIGlzIHRha2luZyBtbXUgbG9ja3Mgd2hpY2ggYXJlCnRha2VuIG9uIG1tdSBub3RpZmllciBw YXRoLCByaWdodD8gIEhvdyBhYm91dCB3ZSBhZGQgYSBzZXFsb2NrIGFuZCB0YWtlCnRoYXQgaW4g aW52YWxpZGF0ZSBjYWxsYmFja3M/ICBXZSBjYW4gdGhlbiBkcm9wIHRoZSBWUSBsb2NrIGJlZm9y ZSBHVVAsCmFuZCB0YWtlIGl0IGFnYWluIGltbWVkaWF0ZWx5IGFmdGVyLgoKc29tZXRoaW5nIGxp a2UKCWlmICghdnFfbWV0YV9tYXBwZWQodnEpKSB7CgkJdnFfbWV0YV9zZXR1cCgmdWFkZHJzKTsK CQltdXRleF91bmxvY2sodnEtPm11dGV4KQoJCXZxX21ldGFfbWFwKCZ1YWRkcnMpOwoJCW11dGV4 X2xvY2sodnEtPm11dGV4KQoKCQkvKiByZWNoZWNrIGJvdGggc29jay0+cHJpdmF0ZV9kYXRhIGFu ZCBzZXFsb2NrIGNvdW50LiAqLwoJCWlmIGNoYW5nZWQgLSBiYWlsIG91dAoJfQoKQW5kIGFsc28g cmVxdWlyZXMgdGhhdCBWUSB1YWRkcnMgaXMgZGVmaW5lZCBsaWtlIHRoaXM6Ci0gd3JpdGVycyBt dXN0IGhhdmUgYm90aCB2cSBtdXRleCBhbmQgZGV2IG11dGV4Ci0gcmVhZGVycyBtdXN0IGhhdmUg ZWl0aGVyIHZxIG11dGV4IG9yIGRldiBtdXRleAoKClRoYXQncyBhIGJpZyBjaGFuZ2UgdGhvdWdo LiBGb3Igbm93LCBob3cgYWJvdXQgc3dpdGNoaW5nIHRvIGEgcGVyLXZxIFNSQ1U/ClRoYXQgaXMg b25seSBhIGxpdHRsZSBiaXQgbW9yZSBleHBlbnNpdmUgdGhhbiBSQ1UsIGFuZCB3ZQpjYW4gdXNl IHN5bmNocm9uaXplX3NyY3VfZXhwZWRpdGVkLgoKLS0gCk1TVAoKX19fX19fX19fX19fX19fX19f X19fX19fX19fX19fX19fX19fX19fX19fX19fX18KbGludXgtYXJtLWtlcm5lbCBtYWlsaW5nIGxp c3QKbGludXgtYXJtLWtlcm5lbEBsaXN0cy5pbmZyYWRlYWQub3JnCmh0dHA6Ly9saXN0cy5pbmZy YWRlYWQub3JnL21haWxtYW4vbGlzdGluZm8vbGludXgtYXJtLWtlcm5lbAo=