From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 99E7A381EBE for ; Sun, 6 Sep 2026 06:52:07 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788677529; cv=none; b=qbVNscAdE30bc0ZIL/IGZKVxL+EBxq7EEktzOTELgAyMHSagE/fGSKTKLi68YZy/p/p/xJO7GNOSf7NltxmqQrGYuIt3RXl7Rs8vkq+RgcwRIhrY5c9+L6Dm+vocsYy4luyKFafZC4g6Rt8RCb8foA9QS2GwHHyl2eR5P+NVbxo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788677529; c=relaxed/simple; bh=azD26yiQNPU/p1yFpKDui4//CMQZvxbCQYRnod40ADo=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=ECIh2lMT0aBFHPVeJ7sUoohPaqTxDBxtH8UDYb16769riyGlJmPgujBYJo8FN0Tk6B7XRfPBo7jMBPz8Rk74vZovPn8Zz14Fqwkmb06J7FdIJ41QUekvfAZ4LoMUFdKjxObtB2NsneDZ5rO6bwVRxGvW8nXdPaG0IPvcjJNVG1s= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=WC/pmLF8; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b=iRYqGxf5; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WC/pmLF8"; dkim=pass (2048-bit key) header.d=redhat.com header.i=@redhat.com header.b="iRYqGxf5" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1788677526; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=RFAyqu/vjWVl9+ogYvQ74BpZIagkpPa2HIVHVUx9n8A=; b=WC/pmLF8XZX+T6aS00R559+fczg6hAefHq5/Mir9jo98+lnanfI7uwOd5GAfUol0hJztSk 9PAi2jMBO37ct27SjUHpAGS2umJAyQ7QjYRjtPHBNgC5s/aIekxsiuBpDuMQSVhsvtUZl/ ubJrburrjzP6vB/NBeBNuJxESKha4K0= Received: from mail-wm1-f71.google.com (mail-wm1-f71.google.com [209.85.128.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-383-g_K_W4GkPJmmAUUNj4JN-w-1; Sun, 06 Sep 2026 02:52:05 -0400 X-MC-Unique: g_K_W4GkPJmmAUUNj4JN-w-1 X-Mimecast-MFC-AGG-ID: g_K_W4GkPJmmAUUNj4JN-w_1788677524 Received: by mail-wm1-f71.google.com with SMTP id 5b1f17b1804b1-495529a93f9so22520575e9.3 for ; Sat, 05 Sep 2026 23:52:05 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=google; t=1788677524; x=1789282324; darn=vger.kernel.org; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:from:to:cc:subject :date:message-id:reply-to:content-type; bh=RFAyqu/vjWVl9+ogYvQ74BpZIagkpPa2HIVHVUx9n8A=; b=iRYqGxf5fa55vS2oLqVWYDIfoa05K+wOsXfFu4QeEHKcMXgxdaP3432tVk79/e3QYX OKeYapsYeFbZ9a/8l61H+H39unKRiOiQ56r2q3+SCKqM30+HfTwh5yYBdy9L+fhEKDTO +T/8gK5ToREWB3lwjBfYj/Pz1iaoEd3OdlhGIM2UIxmomvxPYn58qw/okRXTvlHHHwjl RSf/Z5F7NR3P/Dv8pwYG1C/Ys1I1Laze33VM8UMFevSGuHoaz7kW7/2zBuSjQ2cGamF6 LexhDwmVYp2Sdtc81M50ggU54Xgu7Ff860QiLMOUbjtZczJTtN/OvfglGg/yXb3Pr+gH wYeA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788677524; x=1789282324; h=in-reply-to:content-disposition:content-type:mime-version :references:message-id:subject:cc:to:from:date:x-gm-gg :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=RFAyqu/vjWVl9+ogYvQ74BpZIagkpPa2HIVHVUx9n8A=; b=gRTuPyTPVU0upLVv7CisNiSfF9GwWTt4WMafOx5TCDzRtUZNnWoHwoLJfpSigead2d Ugjwh8Ck2daAor3Bsygvqu3obce/3727aIQ4bWLpZtzE30FgJmhV2sym7egCL9fqs2Q2 c2vXXlflojghYzJ6WncYFLHZXKGhZwoJJkAMYphxCVGIMK4kOQUUX5rQZVDf2vLwgQy/ larSkGgXjUbGNDgjhjRDSJgmB1MjCD9gzXluRHgQamBGi//mT3UCuMDoEUNUFUjU13oL ggvC+nBj8tbk9WPsSTO+4d2Nss/uNZ3q10SW5LSEvikTaB8p7JkJ8IvZdMAVYg2NyK/6 1QuQ== X-Forwarded-Encrypted: i=1; AKwUvByDbTBNcfeAk6Uen1GpbS9I4Bpd3kphz+qif0pHMDBbbj5x0BYsZ73Y2qvEFvBu3N+CuvM=@vger.kernel.org X-Gm-Message-State: AFuF++mVKWAByeLxScCXakOaqDCRrFlGJ3kUs3jed8Votej+kawLLhTL CY9umjLtnTzTHylEur2o/M8Ae7eYRhWXsVvV2nW7psFn/kcUTAkaVFFoU6Q7M/8Qm7MgWVXcNHB P7bGxk2DCQbCuP+5xIJvkNUD8uK/51TY6u1O8qsTwZUa4EW0CzOIvBg== X-Gm-Gg: AYBFou3NxNPMkmieJ3OL2E5HSUxbFw79cS7AASMQuHVWK9GIdYNXQIsDedecmgei5p1 2bjidgTkXnE5MWcrh6BFLx0COdOTQ/aHpAiCiXOkCOYvMJ/5bcRFmD09jaaQRNUWKQEUPXypkVv 5zwtWzSQcdtIe3fctIprFRzf0sBvaFq9kIxSOJB/hKstWiDDMwyuvqx/9IliK1xn/Fb3kzwUgwq Jsg8KnXHCAUWXRdOE+VVQPZ5OmlZitOBuy9Wn7TlyTV823AgSkFbEwlt1HAtb3mpOkkvvLO4jaX YOpMuv6pTYctwPTzDKPZla0JuZRJVgKkkjHQAKUc+FO/QbziUgBrgQnapa9uZKHHbO0yqSBsRFI AhaNbDPm87gLbj07CtDGnuJY= X-Received: by 2002:a05:600c:8b32:b0:49b:d03:8d3a with SMTP id 5b1f17b1804b1-49cf8244878mr177241155e9.11.1788677523938; Sat, 05 Sep 2026 23:52:03 -0700 (PDT) X-Received: by 2002:a05:600c:8b32:b0:49b:d03:8d3a with SMTP id 5b1f17b1804b1-49cf8244878mr177240555e9.11.1788677523479; Sat, 05 Sep 2026 23:52:03 -0700 (PDT) Received: from redhat.com (IGLD-80-230-79-236.inter.net.il. [80.230.79.236]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-48588135600sm16190990f8f.2.2026.09.05.23.52.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 05 Sep 2026 23:52:02 -0700 (PDT) Date: Sun, 6 Sep 2026 02:51:58 -0400 From: "Michael S. Tsirkin" To: Karl Mehltretter Cc: Jason Wang , Gerd Hoffmann , Xuan Zhuo , Eugenio =?iso-8859-1?Q?P=E9rez?= , Dmitry Torokhov , Rusty Russell , Pawel Moll , Cornelia Huck , Halil Pasic , Eric Farman , Richard Weinberger , Anton Ivanov , Johannes Berg , Hans de Goede , Ilpo =?iso-8859-1?Q?J=E4rvinen?= , Vadim Pasternak , Bjorn Andersson , Mathieu Poirier , virtualization@lists.linux.dev, linux-input@vger.kernel.org, linux-s390@vger.kernel.org, kvm@vger.kernel.org, linux-um@lists.infradead.org, platform-driver-x86@vger.kernel.org, linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 2/3] virtio_input: stop callbacks before unregistering input device Message-ID: <20260906025002-mutt-send-email-mst@kernel.org> References: <20260905152059.89560-1-kmehltretter@gmail.com> <20260905152059.89560-3-kmehltretter@gmail.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260905152059.89560-3-kmehltretter@gmail.com> On Sat, Sep 05, 2026 at 05:20:58PM +0200, Karl Mehltretter wrote: > virtinput_remove() unregisters the input device before resetting the > virtio device. virtinput_recv_events() drops vi->lock around input_event(), > so clearing vi->ready does not stop a callback that passed the entry check. > It can still use vi->idev, requeue buffers and kick the queue. > > Reset first, as virtinput_freeze() already does. With the preceding core > change, reset waits for callbacks before input_unregister_device() can > free vi->idev. Recheck vi->ready after taking the lock again: keep draining > completed events so an input packet is not truncated, but stop requeueing > buffers and kicking the queue. > > With evdev attached, input_unregister_handle() currently waits for an RCU > grace period, which also waits out IRQ callbacks. This masks the lifetime > bug on PCI and MMIO, but does not protect sleepable callbacks on other > transports. And now I am completely confused. So it is other transports you are worried about? Which ones did you test? And why don't you worry about fixing other transports in 1/3? > Fixes: 271c865161c5 ("Add virtio-input driver.") > Assisted-by: LLM > Signed-off-by: Karl Mehltretter > --- > drivers/virtio/virtio_input.c | 8 ++++++-- > 1 file changed, 6 insertions(+), 2 deletions(-) > > diff --git a/drivers/virtio/virtio_input.c b/drivers/virtio/virtio_input.c > index deec24e8e682..7b654af0a42c 100644 > --- a/drivers/virtio/virtio_input.c > +++ b/drivers/virtio/virtio_input.c > @@ -49,9 +49,12 @@ static void virtinput_recv_events(struct virtqueue *vq) > le16_to_cpu(event->code), > le32_to_cpu(event->value)); > spin_lock_irqsave(&vi->lock, flags); > + if (!vi->ready) > + continue; > virtinput_queue_evtbuf(vi, event); > } > - virtqueue_kick(vq); > + if (vi->ready) > + virtqueue_kick(vq); > } > spin_unlock_irqrestore(&vi->lock, flags); > } > @@ -350,8 +353,9 @@ static void virtinput_remove(struct virtio_device *vdev) > vi->ready = false; > spin_unlock_irqrestore(&vi->lock, flags); > > - input_unregister_device(vi->idev); > + /* Callbacks use vi->idev. */ > virtio_reset_device(vdev); > + input_unregister_device(vi->idev); > while ((buf = virtqueue_detach_unused_buf(vi->sts)) != NULL) > kfree(buf); > vdev->config->del_vqs(vdev); > -- > 2.39.5 (Apple Git-154)