From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Sender: List-Post: List-Help: List-Unsubscribe: List-Subscribe: Received: from lists.oasis-open.org (oasis-open.org [10.110.1.242]) by lists.oasis-open.org (Postfix) with ESMTP id D7BAD98630B for ; Sun, 5 Jun 2022 20:29:23 +0000 (UTC) Date: Sun, 5 Jun 2022 16:29:08 -0400 From: "Michael S. Tsirkin" Message-ID: <20220605162839-mutt-send-email-mst@kernel.org> References: <6355541D-E117-4E7F-B5D9-3CD0028ED7FF@apple.com> MIME-Version: 1.0 In-Reply-To: <6355541D-E117-4E7F-B5D9-3CD0028ED7FF@apple.com> Subject: Re: [virtio-dev] Clarification of VIRTIO_F_EVENT_IDX driver conditions. Content-Type: text/plain; charset=us-ascii Content-Disposition: inline To: Patrick Mosca Cc: Virtio-Dev , Cameron Esfahani List-ID: On Wed, Jun 01, 2022 at 01:03:27PM -0700, Patrick Mosca wrote: > We ran into an edge case in the VIRTIO_F_EVENT_IDX feature where a notification could be missed if there is a "streak" in skipped notifications. If the difference between the event index and available index wraps before a notification is needed, there exists a case where a notification must be sent but is not sent. > > > Signed-off-by: Patrick Mosca > Signed-off-by: Cameron Esfahani > --- > split-ring.tex | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/split-ring.tex b/split-ring.tex > index bfef62d..9650e5e 100644 > --- a/split-ring.tex > +++ b/split-ring.tex > @@ -530,6 +530,9 @@ \subsection{Available Buffer Notification Suppression}\label{sec:Basic Facilitie > \item If the \field{idx} field in the available ring (which determined > where that descriptor index was placed) was equal to > \field{avail_event}, the driver MUST send a notification. > + \item If the number of descriptors added to the queue since > + the last notification is greater than 65535, the driver MUST > + send a notification. > \item Otherwise the driver SHOULD NOT send a notification. > \end{itemize} > \end{itemize} > -- > 2.32.0 (Apple Git-131) > > > -Patrick Mosca I am not sure I understand. Can you give an example of how the issue triggers please? -- MST --------------------------------------------------------------------- To unsubscribe, e-mail: virtio-dev-unsubscribe@lists.oasis-open.org For additional commands, e-mail: virtio-dev-help@lists.oasis-open.org