From patchwork Thu Jul 17 17:41:50 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Khalid Aziz X-Patchwork-Id: 371231 X-Patchwork-Delegate: davem@davemloft.net Return-Path: X-Original-To: patchwork-incoming@ozlabs.org Delivered-To: patchwork-incoming@ozlabs.org Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id A409014014F for ; Fri, 18 Jul 2014 03:42:03 +1000 (EST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751045AbaGQRmC (ORCPT ); Thu, 17 Jul 2014 13:42:02 -0400 Received: from qmta01.emeryville.ca.mail.comcast.net ([76.96.30.16]:50905 "EHLO qmta01.emeryville.ca.mail.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751100AbaGQRmB (ORCPT ); Thu, 17 Jul 2014 13:42:01 -0400 Received: from omta23.emeryville.ca.mail.comcast.net ([76.96.30.90]) by qmta01.emeryville.ca.mail.comcast.net with comcast id TUdD1o0031wfjNsA1Vi0DL; Thu, 17 Jul 2014 17:42:00 +0000 Received: from mail.gonehiking.org ([50.134.149.16]) by omta23.emeryville.ca.mail.comcast.net with comcast id TVhz1o0060MU7Qa8jVhzZh; Thu, 17 Jul 2014 17:42:00 +0000 Received: from concerto.us.oracle.com (concerto-wl.internal [192.168.1.22]) by mail.gonehiking.org (Postfix) with ESMTP id AA0FF3FF2E; Thu, 17 Jul 2014 11:41:58 -0600 (MDT) From: Khalid Aziz To: davem@davemloft.net Cc: Khalid Aziz , sparclinux@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v2] sparc: Add support for seek and shorter read to /dev/mdesc Date: Thu, 17 Jul 2014 11:41:50 -0600 Message-Id: <1405618910-17667-1-git-send-email-khalid.aziz@oracle.com> X-Mailer: git-send-email 1.9.1 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=comcast.net; s=q20140121; t=1405618920; bh=vkssZ5FaVRfTMoQwf/UJTjE2tt25sIvmbl+4P2Z+8sc=; h=Received:Received:Received:From:To:Subject:Date:Message-Id; b=TGaJZ462JtwJlBQwS06/Tghu0gpt/foDZb/mYbznqoPhr8OA8OfeC61XIGfU0ZWQv ixf4bXc649QYzw9tIZXn2phwTUXvBxLn6WhpmBoGQ16A8iCX+hCf7UvcpuEz387SEP QgRhz7cJrHBAJYyNYvKidS/EMl7xdPGO9Ls3cyKACh6YLGwpsSVjBMcBReAKwWLBew CnlG+Fm90uxpO+vmazjljhY6x1/k5WXBjXI1tq60luSERmyBBfjqfQftscF0lY0gR0 boCSub+wBLi8Qeq9NhxYk4orQq+Vu+6RWf0QpHPGNlvxVQAR7chUxrDfWo9wYIoA7e b/EliShsjrsLw== Sender: sparclinux-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: sparclinux@vger.kernel.org /dev/mdesc on Linux does not support reading arbitrary number of bytes and seeking while /dev/mdesc on Solaris does. This causes tools that work on Solaris to break on Linux. This patch adds these two capabilities to /dev/mdesc. Signed-off-by: Khalid Aziz --- v2: - Cleaned up code in mdesc_read() and mdesc_llseek() to be more readable arch/sparc/kernel/mdesc.c | 80 +++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 67 insertions(+), 13 deletions(-) diff --git a/arch/sparc/kernel/mdesc.c b/arch/sparc/kernel/mdesc.c index a1a4400..be7d245 100644 --- a/arch/sparc/kernel/mdesc.c +++ b/arch/sparc/kernel/mdesc.c @@ -906,29 +906,83 @@ void mdesc_fill_in_cpu_data(cpumask_t *mask) smp_fill_in_sib_core_maps(); } -static ssize_t mdesc_read(struct file *file, char __user *buf, - size_t len, loff_t *offp) +/* mdesc_open() - Grab a reference to mdesc_handle when /dev/mdesc is + * opened. Hold this reference until /dev/mdesc is closed to ensure + * mdesc data structure is not released underneath us. Store the + * pointer to mdesc structure in private_data for read and seek to use + */ +static int mdesc_open(struct inode *inode, struct file *file) { struct mdesc_handle *hp = mdesc_grab(); - int err; if (!hp) return -ENODEV; - err = hp->handle_size; - if (len < hp->handle_size) - err = -EMSGSIZE; - else if (copy_to_user(buf, &hp->mdesc, hp->handle_size)) - err = -EFAULT; - mdesc_release(hp); + file->private_data = hp; + return 0; +} - return err; +static ssize_t mdesc_read(struct file *file, char __user *buf, + size_t len, loff_t *offp) +{ + struct mdesc_handle *hp = file->private_data; + unsigned char *mdesc; + int bytes_left, count = len; + + if (*offp >= hp->handle_size) + return 0; + + bytes_left = hp->handle_size - *offp; + if (count > bytes_left) + count = bytes_left; + + mdesc = (unsigned char *)&hp->mdesc; + mdesc += *offp; + if (!copy_to_user(buf, mdesc, count)) { + *offp += count; + return count; + } else { + return -EFAULT; + } +} + +static loff_t mdesc_llseek(struct file *file, loff_t offset, int whence) +{ + struct mdesc_handle *hp; + + switch (whence) { + case SEEK_CUR: + offset += file->f_pos; + break; + case SEEK_SET: + break; + default: + return -EINVAL; + } + + hp = file->private_data; + if (offset > hp->handle_size) + return -EINVAL; + else + file->f_pos = offset; + return offset; +} + +/* mdesc_close() - /dev/mdesc is being closed, release the reference to + * mdesc structure. + */ +static int mdesc_close(struct inode *inode, struct file *file) +{ + mdesc_release(file->private_data); + return 0; } static const struct file_operations mdesc_fops = { - .read = mdesc_read, - .owner = THIS_MODULE, - .llseek = noop_llseek, + .open = mdesc_open, + .read = mdesc_read, + .llseek = mdesc_llseek, + .release = mdesc_close, + .owner = THIS_MODULE, }; static struct miscdevice mdesc_misc = {