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=no 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 EED45C43603 for ; Wed, 18 Dec 2019 17:28:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id CD1FE2072B for ; Wed, 18 Dec 2019 17:28:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727281AbfLRR2X (ORCPT ); Wed, 18 Dec 2019 12:28:23 -0500 Received: from isilmar-4.linta.de ([136.243.71.142]:36504 "EHLO isilmar-4.linta.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726960AbfLRR2X (ORCPT ); Wed, 18 Dec 2019 12:28:23 -0500 X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES X-isilmar-external: YES Received: from light.dominikbrodowski.net (brodo.linta [10.1.0.102]) by isilmar-4.linta.de (Postfix) with ESMTPSA id B81CF200713; Wed, 18 Dec 2019 17:28:21 +0000 (UTC) Received: by light.dominikbrodowski.net (Postfix, from userid 1000) id BC1DE20BAB; Wed, 18 Dec 2019 18:28:13 +0100 (CET) Date: Wed, 18 Dec 2019 18:28:13 +0100 From: Dominik Brodowski To: Jia-Ju Bai Cc: miquel.raynal@bootlin.com, richard@nod.at, vigneshr@ti.com, linux-mtd@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mtd: maps: pcmciamtd: fix possible sleep-in-atomic-context bugs in pcmciamtd_set_vpp() Message-ID: <20191218172813.GA338501@light.dominikbrodowski.net> References: <20191218140552.12249-1-baijiaju1990@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20191218140552.12249-1-baijiaju1990@gmail.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Dec 18, 2019 at 10:05:52PM +0800, Jia-Ju Bai wrote: > The driver may sleep while holding a spinlock. > The function call path (from bottom to top) in Linux 4.19 is: > > drivers/pcmcia/pcmcia_resource.c, 312: > mutex_lock in pcmcia_fixup_vpp > drivers/mtd/maps/pcmciamtd.c, 309: > pcmcia_fixup_vpp in pcmciamtd_set_vpp > drivers/mtd/maps/pcmciamtd.c, 306: > _raw_spin_lock_irqsave in pcmciamtd_set_vpp > > drivers/pcmcia/pcmcia_resource.c, 312: > mutex_lock in pcmcia_fixup_vpp > drivers/mtd/maps/pcmciamtd.c, 312: > pcmcia_fixup_vpp in pcmciamtd_set_vpp > drivers/mtd/maps/pcmciamtd.c, 306: > _raw_spin_lock_irqsave in pcmciamtd_set_vp > > mutex_lock() may sleep at runtime. Thanks for noticing this issue. > To fix these bugs, pcmcia_fixup_vpp() is called without holding the > spinlock. I don't think that this is the right approach here -- we lose the protection against races in calls to pcmcia_fixup_vpp(). Instead, we should change the spinlock to a mutex, which seems to be sufficient here. Could you prepare such a patch, please? Thanks, Dominik