From patchwork Wed Dec 8 20:52:28 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Matthias Kaehlcke X-Patchwork-Id: 12665255 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CF66C433EF for ; Wed, 8 Dec 2021 20:52:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234673AbhLHU4G (ORCPT ); Wed, 8 Dec 2021 15:56:06 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47102 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234670AbhLHU4F (ORCPT ); Wed, 8 Dec 2021 15:56:05 -0500 Received: from mail-pl1-x62f.google.com (mail-pl1-x62f.google.com [IPv6:2607:f8b0:4864:20::62f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 98E8BC0617A1 for ; Wed, 8 Dec 2021 12:52:33 -0800 (PST) Received: by mail-pl1-x62f.google.com with SMTP id v19so2346538plo.7 for ; Wed, 08 Dec 2021 12:52:33 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=MaavrIqhkG9MrVF6nusejPSx0dASpN7sJH0FwNNenx4=; b=Iecx+r5j7lYuIaTNs+suMFVQzlh8kODNOPgOsNMiX8aSlptlaR1JqWCMKE4CwgjI+Y jm69T7+B7GfSgSOw5okFXbQwcXDmj2dRD7WWa+4A9PvmzxDZyvnfwJhWZvA0gXUEm/kU j2egkHhPlMCC1N2lS+ZI0pRPXVySAE8azBOYk= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=MaavrIqhkG9MrVF6nusejPSx0dASpN7sJH0FwNNenx4=; b=ZoPwbDmZd3mtmt2sbJ+BnjCVpdt8z9X1NWVCEr3Swh6+ak1FczidwzHVKawYbouylM NMej7FQqKUkR10WQAnfEWV5Fe3s+uvWPpMEV+8Zf6Bdcc3/6XRGwmH8RLzj7L1M0LRc/ fe28qOFqJSl/N2eT5TRGfgTUdxRZnTi2pmsXtj409IONgrNGwNRHaeLJQ4KTRx13JN1l nugz34RvmgprvewFnartzfYjdGKHRoETvX144LGhQlcXB6o0YRRYQovsISQDYXb+LO2a Rvb4+BXgYjIxfUG9NcXoqsty01wcaOPAoj5AIf8kBgJqdYx49ghul0HCcTUhDl+ACd69 cZYw== X-Gm-Message-State: AOAM532YGB2hSzNJhH4uUUhRDQlGQPoV9DyT9qH9fkGa1e6F0GWtx5Jm iqHcERii2d/GqN3wYU7YC2HudQ== X-Google-Smtp-Source: ABdhPJyUtx7NGJpqN0rQ3/qPSP8p+Gj+ZVQX59sIDU35U4DFdNYrYR93/ixBEjG7b0ot0mXtwII/GQ== X-Received: by 2002:a17:90a:4894:: with SMTP id b20mr9988254pjh.121.1638996753035; Wed, 08 Dec 2021 12:52:33 -0800 (PST) Received: from localhost ([2620:15c:202:201:e328:454f:88d0:4ad1]) by smtp.gmail.com with UTF8SMTPSA id r21sm4173852pfh.128.2021.12.08.12.52.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 08 Dec 2021 12:52:32 -0800 (PST) From: Matthias Kaehlcke To: Andy Gross , Ohad Ben-Cohen Cc: Stephen Boyd , Sibi Sankar , Sujit Kautkar , Bjorn Andersson , linux-remoteproc@vger.kernel.org, linux-kernel@vger.kernel.org, Matthias Kaehlcke , Mathieu Poirier Subject: [PATCH v4] rpmsg: char: Fix race between the release of rpmsg_ctrldev and cdev Date: Wed, 8 Dec 2021 12:52:28 -0800 Message-Id: <20211208125220.v4.1.Iaac908f3e3149a89190ce006ba166e2d3fd247a3@changeid> X-Mailer: git-send-email 2.34.1.400.ga245620fadb-goog MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-remoteproc@vger.kernel.org From: Sujit Kautkar From: Sujit Kautkar struct rpmsg_ctrldev contains a struct cdev. The current code frees the rpmsg_ctrldev struct in rpmsg_ctrldev_release_device(), but the cdev is a managed object, therefore its release is not predictable and the rpmsg_ctrldev could be freed before the cdev is entirely released, as in the backtrace below. [ 93.625603] ODEBUG: free active (active state 0) object type: timer_list hint: delayed_work_timer_fn+0x0/0x7c [ 93.636115] WARNING: CPU: 0 PID: 12 at lib/debugobjects.c:488 debug_print_object+0x13c/0x1b0 [ 93.644799] Modules linked in: veth xt_cgroup xt_MASQUERADE rfcomm algif_hash algif_skcipher af_alg uinput ip6table_nat fuse uvcvideo videobuf2_vmalloc venus_enc venus_dec videobuf2_dma_contig hci_uart btandroid btqca snd_soc_rt5682_i2c bluetooth qcom_spmi_temp_alarm snd_soc_rt5682v [ 93.715175] CPU: 0 PID: 12 Comm: kworker/0:1 Tainted: G B 5.4.163-lockdep #26 [ 93.723855] Hardware name: Google Lazor (rev3 - 8) with LTE (DT) [ 93.730055] Workqueue: events kobject_delayed_cleanup [ 93.735271] pstate: 60c00009 (nZCv daif +PAN +UAO) [ 93.740216] pc : debug_print_object+0x13c/0x1b0 [ 93.744890] lr : debug_print_object+0x13c/0x1b0 [ 93.749555] sp : ffffffacf5bc7940 [ 93.752978] x29: ffffffacf5bc7940 x28: dfffffd000000000 [ 93.758448] x27: ffffffacdb11a800 x26: dfffffd000000000 [ 93.763916] x25: ffffffd0734f856c x24: dfffffd000000000 [ 93.769389] x23: 0000000000000000 x22: ffffffd0733c35b0 [ 93.774860] x21: ffffffd0751994a0 x20: ffffffd075ec27c0 [ 93.780338] x19: ffffffd075199100 x18: 00000000000276e0 [ 93.785814] x17: 0000000000000000 x16: dfffffd000000000 [ 93.791291] x15: ffffffffffffffff x14: 6e6968207473696c [ 93.796768] x13: 0000000000000000 x12: ffffffd075e2b000 [ 93.802244] x11: 0000000000000001 x10: 0000000000000000 [ 93.807723] x9 : d13400dff1921900 x8 : d13400dff1921900 [ 93.813200] x7 : 0000000000000000 x6 : 0000000000000000 [ 93.818676] x5 : 0000000000000080 x4 : 0000000000000000 [ 93.824152] x3 : ffffffd0732a0fa4 x2 : 0000000000000001 [ 93.829628] x1 : ffffffacf5bc7580 x0 : 0000000000000061 [ 93.835104] Call trace: [ 93.837644] debug_print_object+0x13c/0x1b0 [ 93.841963] __debug_check_no_obj_freed+0x25c/0x3c0 [ 93.846987] debug_check_no_obj_freed+0x18/0x20 [ 93.851669] slab_free_freelist_hook+0xbc/0x1e4 [ 93.856346] kfree+0xfc/0x2f4 [ 93.859416] rpmsg_ctrldev_release_device+0x78/0xb8 [ 93.864445] device_release+0x84/0x168 [ 93.868310] kobject_cleanup+0x12c/0x298 [ 93.872356] kobject_delayed_cleanup+0x10/0x18 [ 93.876948] process_one_work+0x578/0x92c [ 93.881086] worker_thread+0x804/0xcf8 [ 93.884963] kthread+0x2a8/0x314 [ 93.888303] ret_from_fork+0x10/0x18 The cdev_device_add/del() API was created to address this issue (see commit 233ed09d7fda), use it instead of cdev add/del(). Signed-off-by: Sujit Kautkar Signed-off-by: Matthias Kaehlcke Reviewed-by: Stephen Boyd Reviewed-by: Mathieu Poirier Reviewed-by: Bjorn Andersson --- Changes in v4: - call cdev_device_del() from rpmsg_chrdev_remove() instead of rpmsg_ctrldev_release_device() - updated subject (was: "rpmsg: glink: Update cdev add/del API in rpmsg_ctrldev_release_device()") - updated commit message - replaced backtrace in commit message with one that doesn't have a dump_backtrace() call Changes in v3: - Remove unecessary error check as per Matthias's comment Changes in v2: - Fix typo in commit message drivers/rpmsg/rpmsg_char.c | 11 ++--------- 1 file changed, 2 insertions(+), 9 deletions(-) diff --git a/drivers/rpmsg/rpmsg_char.c b/drivers/rpmsg/rpmsg_char.c index b5907b80727c..b1b75ef04560 100644 --- a/drivers/rpmsg/rpmsg_char.c +++ b/drivers/rpmsg/rpmsg_char.c @@ -459,7 +459,6 @@ static void rpmsg_ctrldev_release_device(struct device *dev) ida_simple_remove(&rpmsg_ctrl_ida, dev->id); ida_simple_remove(&rpmsg_minor_ida, MINOR(dev->devt)); - cdev_del(&ctrldev->cdev); kfree(ctrldev); } @@ -494,19 +493,13 @@ static int rpmsg_chrdev_probe(struct rpmsg_device *rpdev) dev->id = ret; dev_set_name(&ctrldev->dev, "rpmsg_ctrl%d", ret); - ret = cdev_add(&ctrldev->cdev, dev->devt, 1); + ret = cdev_device_add(&ctrldev->cdev, &ctrldev->dev); if (ret) goto free_ctrl_ida; /* We can now rely on the release function for cleanup */ dev->release = rpmsg_ctrldev_release_device; - ret = device_add(dev); - if (ret) { - dev_err(&rpdev->dev, "device_add failed: %d\n", ret); - put_device(dev); - } - dev_set_drvdata(&rpdev->dev, ctrldev); return ret; @@ -532,7 +525,7 @@ static void rpmsg_chrdev_remove(struct rpmsg_device *rpdev) if (ret) dev_warn(&rpdev->dev, "failed to nuke endpoints: %d\n", ret); - device_del(&ctrldev->dev); + cdev_device_del(&ctrldev->cdev, &ctrldev->dev); put_device(&ctrldev->dev); }