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=unavailable 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 5260AC31E45 for ; Thu, 13 Jun 2019 16:46:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2A9B820673 for ; Thu, 13 Jun 2019 16:46:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730323AbfFMQpy (ORCPT ); Thu, 13 Jun 2019 12:45:54 -0400 Received: from lb3-smtp-cloud7.xs4all.net ([194.109.24.31]:47215 "EHLO lb3-smtp-cloud7.xs4all.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730319AbfFMFoV (ORCPT ); Thu, 13 Jun 2019 01:44:21 -0400 Received: from [192.168.2.10] ([46.9.252.75]) by smtp-cloud7.xs4all.net with ESMTPA id bIX1hL32N5qKabIX4hDxVJ; Thu, 13 Jun 2019 07:44:19 +0200 Subject: Re: [PATCH 0/2] Use Media Dev Allocator to fix vimc dev lifetime bugs To: helen.koike@collabora.com Cc: Shuah Khan , linux-media@vger.kernel.org, linux-kernel@vger.kernel.org References: From: Hans Verkuil Message-ID: Date: Thu, 13 Jun 2019 07:44:15 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-CMAE-Envelope: MS4wfDwxpIXPhJN75Jw4Kp1rhsRbTfMtOhFu8gNd1BX+22wfx+C4LbiSCZR9QW2IynSwuVRELuLWlzdy123Z9GqnH8K5Ut/QIsYFRlAz8e0zn4l6PAyDEFF/ 8e5YMZHzequKkwwJdLY6CDvGb6f67csd4nqD0iAmn5DG+zJOYvS2GJhtfMdwRNhsusrA9doOHJSgntKDjUYCKH3PYUxKW3v7DiivRZS2/2y5kkIK/M9krJ3w nAjQl97buif4pFG7oZdhdmwC0o4QazU2MJ2AM5aYGV0Ex+YrIZPXv2BRycaklV+EvDc/9SX4cMhE95rGSGmURw== Sender: linux-media-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-media@vger.kernel.org On 5/24/19 5:31 AM, Shuah Khan wrote: > media_device is embedded in struct vimc_device and when vimc is removed > vimc_device and the embedded media_device goes with it, while the active > stream and vimc_capture continue to access it. > > Fix the media_device lifetime problem by changing vimc to create shared > media_device using Media Device Allocator API and vimc_capture getting > a reference to vimc module. With this change, vimc module can be removed > only when the references are gone. vimc can be removed after vimc_capture > is removed. > > Media Device Allocator API supports just USB devices. Enhance it > adding a genetic device allocate interface to support other media > drivers. > > The new interface takes pointer to struct device instead and creates > media device. This interface allows a group of drivers that have a > common root device to share media device resource and ensure media > device doesn't get deleted as long as one of the drivers holds its > reference. > > The new interface has been tested with vimc component driver to fix > panics when vimc module is removed while streaming is in progress. Helen, can you review this series? I'm not sure this is the right approach for a driver like vimc, and even if it is, then it is odd that vimc-capture is the only vimc module that's handled here. My gut feeling is that this should be handled inside vimc directly and not using the media-dev-allocator. Regards, Hans > > Shuah Khan (2): > media: add generic device allocate interface to media-dev-allocator > vimc: fix BUG: unable to handle kernel NULL pointer dereference > > drivers/media/Makefile | 4 +- > drivers/media/media-dev-allocator.c | 39 ++++++++++++++ > drivers/media/platform/vimc/vimc-capture.c | 17 +++++- > drivers/media/platform/vimc/vimc-core.c | 60 ++++++++++++---------- > include/media/media-dev-allocator.h | 46 ++++++++++++++--- > 5 files changed, 130 insertions(+), 36 deletions(-) >