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=-6.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham 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 13BE2C32751 for ; Sat, 10 Aug 2019 18:13:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E35032085B for ; Sat, 10 Aug 2019 18:13:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726165AbfHJSM7 (ORCPT ); Sat, 10 Aug 2019 14:12:59 -0400 Received: from mail-qk1-f195.google.com ([209.85.222.195]:42470 "EHLO mail-qk1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726055AbfHJSM7 (ORCPT ); Sat, 10 Aug 2019 14:12:59 -0400 Received: by mail-qk1-f195.google.com with SMTP id 201so74120599qkm.9 for ; Sat, 10 Aug 2019 11:12:58 -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:in-reply-to; bh=Rl3GYKdvkUhjJZod4R7cIwaGENcluFkd1m8GRMDLYjA=; b=W5aYhRKsb3F/FZb5mxGfheLLlcP17VSgOLEuxU7oHErPmZ9GHgWcHHGGicF4VHvAHx UHMDm6FvSVERVcCXx4vtDcLsGX7MYF4XpaXJCaLFGoQprhSB/eE98EdMg6JEvc3+yUBu +ysgdLy2rjH/bMujOvGzwdQNwQENCUHbxz0IoHjobdavVyrUUCQCMZuhGOoVJ9VUPbmc /l/R+5sbMHiKylevBfcF05lyuqspqqRLHCZ5R78Sh6Y6tNa8IyUeOESg3jG1AM1BEASv w3LkrTvNxJkIAnnMlAacEVXmJXhA8f8oc/PQGAKrFRt6Gu6JXfsXSrXK88dYh3PajRVk UvUA== X-Gm-Message-State: APjAAAV8OHlPJKAGpxqETCcY1pQCgw+yytFIXUO2CO3SyqpyqEnbQpyi smRZs7mslQ7L8yyG9ZGCpSlClg== X-Google-Smtp-Source: APXvYqwi1TjEBF8tYTsvAGgXLmd4P+ip28ybiTZaq2rLk2el4TcxbT3QBB9TmfjhklDWaGag+v2B+A== X-Received: by 2002:a37:a7d6:: with SMTP id q205mr24016018qke.44.1565460778101; Sat, 10 Aug 2019 11:12:58 -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 h4sm43862894qkk.39.2019.08.10.11.12.54 (version=TLS1_3 cipher=AEAD-AES256-GCM-SHA384 bits=256/256); Sat, 10 Aug 2019 11:12:57 -0700 (PDT) Date: Sat, 10 Aug 2019 14:12:51 -0400 From: "Michael S. Tsirkin" To: Pankaj Gupta Cc: amit@kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org, virtualization@lists.linux-foundation.org, jasowang@redhat.com, linux-kernel@vger.kernel.org, xiaohli@redhat.com Subject: Re: [PATCH v3 2/2] virtio: decrement avail idx with buffer detach for packed ring Message-ID: <20190810141213-mutt-send-email-mst@kernel.org> References: <20190809064847.28918-1-pagupta@redhat.com> <20190809064847.28918-3-pagupta@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190809064847.28918-3-pagupta@redhat.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Aug 09, 2019 at 12:18:47PM +0530, Pankaj Gupta wrote: > This patch decrements 'next_avail_idx' count when detaching a buffer > from vq for packed ring code. Split ring code already does this in > virtqueue_detach_unused_buf_split function. This updates the > 'next_avail_idx' to the previous correct index after an unused buffer > is detatched from the vq. > > Signed-off-by: Pankaj Gupta I would make this patch 1, not patch 2, otherwise patch 1 corrupts the ring. > --- > drivers/virtio/virtio_ring.c | 6 ++++++ > 1 file changed, 6 insertions(+) > > diff --git a/drivers/virtio/virtio_ring.c b/drivers/virtio/virtio_ring.c > index c8be1c4f5b55..7c69181113e2 100644 > --- a/drivers/virtio/virtio_ring.c > +++ b/drivers/virtio/virtio_ring.c > @@ -1537,6 +1537,12 @@ static void *virtqueue_detach_unused_buf_packed(struct virtqueue *_vq) > /* detach_buf clears data, so grab it now. */ > buf = vq->packed.desc_state[i].data; > detach_buf_packed(vq, i, NULL); > + vq->packed.next_avail_idx--; > + if (vq->packed.next_avail_idx < 0) { > + vq->packed.next_avail_idx = vq->packed.vring.num - 1; > + vq->packed.avail_wrap_counter ^= 1; > + } > + > END_USE(vq); > return buf; > } > -- > 2.20.1