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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 CCAA6C43460 for ; Fri, 21 May 2021 06:51:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AA7DA613BD for ; Fri, 21 May 2021 06:51:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234331AbhEUGwo (ORCPT ); Fri, 21 May 2021 02:52:44 -0400 Received: from mail.kernel.org ([198.145.29.99]:33800 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232426AbhEUGwn (ORCPT ); Fri, 21 May 2021 02:52:43 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id ADCE3613BB; Fri, 21 May 2021 06:51:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1621579880; bh=+TlRkCWv2IP2OKDhEW+sR4mAR64PA70bKtB4aLP10Zc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=j8d1j97W11QegLjc7T5xwLpNoyeTn3bTbA4g1L7CPyFcKmgQMp9CZrgWvI6dwR1jK ifeU6OV9FXRCKQIJVx3JshqjtZcDhanD+B2+TKTeanp+WAhu9K7WCvfOL8fFfWsEy5 LfBFiK6oj0iRbHARJ+n5G4R8G8hiX+pbRZv3recc= Date: Fri, 21 May 2021 08:51:16 +0200 From: Greg KH To: Zheyu Ma Cc: cernekee@gmail.com, jirislaby@kernel.org, linux-serial@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2] serial: rp2: use 'request_firmware' instead of 'request_firmware_nowait' Message-ID: References: <1621577323-1541-1-git-send-email-zheyuma97@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1621577323-1541-1-git-send-email-zheyuma97@gmail.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 21, 2021 at 06:08:43AM +0000, Zheyu Ma wrote: > In 'rp2_probe', the driver registers 'rp2_uart_interrupt' then calls > 'rp2_fw_cb' through 'request_firmware_nowait'. In 'rp2_fw_cb', if the > firmware don't exists, function just return without initializing ports > of 'rp2_card'. But now the interrupt handler function has been > registered, and when an interrupt comes, 'rp2_uart_interrupt' may access > those ports then causing NULL pointer dereference or other bugs. > > Because the driver does some initialization work in 'rp2_fw_cb', in > order to make the driver ready to handle interrupts, 'request_firmware' > should be used instead of asynchronous 'request_firmware_nowait'. You just now slowed down the probe function. Are you _sure_ this is ok? Do you have this hardware to test this? If so, what is the init time before and after this change? thanks, greg k-h