From patchwork Mon Dec 2 11:41:16 2019 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Paul Durrant X-Patchwork-Id: 11269061 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 20B3C139A for ; Mon, 2 Dec 2019 11:41:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F3672217D9 for ; Mon, 2 Dec 2019 11:41:44 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=amazon.com header.i=@amazon.com header.b="ZMSMbM27" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727364AbfLBLlk (ORCPT ); Mon, 2 Dec 2019 06:41:40 -0500 Received: from smtp-fw-4101.amazon.com ([72.21.198.25]:39535 "EHLO smtp-fw-4101.amazon.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727442AbfLBLlk (ORCPT ); Mon, 2 Dec 2019 06:41:40 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazon201209; t=1575286900; x=1606822900; h=from:to:cc:subject:date:message-id:in-reply-to: references:mime-version:content-transfer-encoding; bh=kpBDFf/k+zrPeTbYdI5I7muMlPtyB4e1OuL/tO791VQ=; b=ZMSMbM27skGfOIFMZBj0RK+yfgjGhhmCD5XAqF0G1eXNTDQCexUyda1R FDgu/2lFj5uMMDokJDHSgzbWfu0/2AEKUiWnmMP1r0U8VkZG8sAdv+BNi 1NNdIK/tmcBKkdR2kfTDAOmHUyifJHzE9jLZ4Pa3cj7kx6YERI9PIvUNd g=; IronPort-SDR: ZS7ql7Tvf8YlX0tNkMrzXQYROPJAbsMMMFcadgL2BM02EspQF2dEPdMjhLQU0GicnTzzeKr6d1 J10Mvso1JoqQ== X-IronPort-AV: E=Sophos;i="5.69,268,1571702400"; d="scan'208";a="6617703" Received: from iad6-co-svc-p1-lb1-vlan3.amazon.com (HELO email-inbound-relay-2b-8cc5d68b.us-west-2.amazon.com) ([10.124.125.6]) by smtp-border-fw-out-4101.iad4.amazon.com with ESMTP; 02 Dec 2019 11:41:39 +0000 Received: from EX13MTAUEA001.ant.amazon.com (pdx4-ws-svc-p6-lb7-vlan3.pdx.amazon.com [10.170.41.166]) by email-inbound-relay-2b-8cc5d68b.us-west-2.amazon.com (Postfix) with ESMTPS id 828DAA2372; Mon, 2 Dec 2019 11:41:37 +0000 (UTC) Received: from EX13D32EUB003.ant.amazon.com (10.43.166.165) by EX13MTAUEA001.ant.amazon.com (10.43.61.82) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 2 Dec 2019 11:41:37 +0000 Received: from EX13MTAUWB001.ant.amazon.com (10.43.161.207) by EX13D32EUB003.ant.amazon.com (10.43.166.165) with Microsoft SMTP Server (TLS) id 15.0.1367.3; Mon, 2 Dec 2019 11:41:36 +0000 Received: from u2f063a87eabd5f.cbg10.amazon.com (10.125.106.135) by mail-relay.amazon.com (10.43.161.249) with Microsoft SMTP Server id 15.0.1367.3 via Frontend Transport; Mon, 2 Dec 2019 11:41:33 +0000 From: Paul Durrant To: , , CC: Paul Durrant , Jan Beulich , "Boris Ostrovsky" , Juergen Gross , Stefano Stabellini Subject: [PATCH v3 1/2] xen/xenbus: reference count registered modules Date: Mon, 2 Dec 2019 11:41:16 +0000 Message-ID: <20191202114117.1264-2-pdurrant@amazon.com> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20191202114117.1264-1-pdurrant@amazon.com> References: <20191202114117.1264-1-pdurrant@amazon.com> MIME-Version: 1.0 Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org To prevent a PV driver module being removed whilst attached to its other end, and hence xenbus calling into potentially invalid text, take a reference on the module before calling the probe() method (dropping it if unsuccessful) and drop the reference after returning from the remove() method. Suggested-by: Jan Beulich Signed-off-by: Paul Durrant Reviewed-by: Jan Beulich --- Cc: Boris Ostrovsky Cc: Juergen Gross Cc: Stefano Stabellini v2: - New in v2 v3: - Use try_module_get() rather than __module)get() and handle failure - Not added Juergen's R-b because of the change --- drivers/xen/xenbus/xenbus_probe.c | 13 ++++++++++++- 1 file changed, 12 insertions(+), 1 deletion(-) diff --git a/drivers/xen/xenbus/xenbus_probe.c b/drivers/xen/xenbus/xenbus_probe.c index 5b471889d723..4461f4583476 100644 --- a/drivers/xen/xenbus/xenbus_probe.c +++ b/drivers/xen/xenbus/xenbus_probe.c @@ -232,9 +232,16 @@ int xenbus_dev_probe(struct device *_dev) return err; } + if (!try_module_get(drv->driver.owner)) { + dev_warn(&dev->dev, "failed to acquire module reference on '%s'.\n", + drv->driver.name); + err = -ESRCH; + goto fail; + } + err = drv->probe(dev, id); if (err) - goto fail; + goto fail_put; err = watch_otherend(dev); if (err) { @@ -244,6 +251,8 @@ int xenbus_dev_probe(struct device *_dev) } return 0; +fail_put: + module_put(drv->driver.owner); fail: xenbus_dev_error(dev, err, "xenbus_dev_probe on %s", dev->nodename); xenbus_switch_state(dev, XenbusStateClosed); @@ -263,6 +272,8 @@ int xenbus_dev_remove(struct device *_dev) if (drv->remove) drv->remove(dev); + module_put(drv->driver.owner); + free_otherend_details(dev); xenbus_switch_state(dev, XenbusStateClosed);