Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752289Ab1EJVGQ (ORCPT ); Tue, 10 May 2011 17:06:16 -0400 Received: from out2.smtp.messagingengine.com ([66.111.4.26]:49041 "EHLO out2.smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750784Ab1EJVGO (ORCPT ); Tue, 10 May 2011 17:06:14 -0400 X-Sasl-enc: FMqyallK9rEPGdczMsD38MXLgvaWocneKI8XlIxp0/D3 1305061573 Message-ID: <4DC9A8C0.9070502@fastmail.fm> Date: Tue, 10 May 2011 22:06:08 +0100 From: Jack Stone User-Agent: Mozilla/5.0 (Windows; U; Windows NT 6.0; en-GB; rv:1.9.2.17) Gecko/20110414 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: Tim Gardner CC: linux-fbdev@vger.kernel.org, lethal@linux-sh.org, linux-kernel@vger.kernel.org, Andy Whitcroft , Leann Ogasawara Subject: Re: [PATCH V2] fbcon -- fix race between open and removal of framebuffers References: <1304617307-7389-1-git-send-email-tim.gardner@canonical.com> <1304617307-7389-2-git-send-email-tim.gardner@canonical.com> <4DC30FFA.9030708@fastmail.fm> <4DC933EE.70409@canonical.com> In-Reply-To: <4DC933EE.70409@canonical.com> X-Enigmail-Version: 1.1.1 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1300 Lines: 57 Hi Tim, One more quick question: On 10/05/2011 13:47, Tim Gardner wrote: +static struct fb_info *get_framebuffer_info(int idx) +__acquires(®istered_lock) +__releases(®istered_lock) +{ + struct fb_info *fb_info; + + spin_lock(®istered_lock); + fb_info = registered_fb[idx]; + fb_info->ref_count++; + spin_unlock(®istered_lock); + + return fb_info; +} [snip] static int fb_open(struct inode *inode, struct file *file) __acquires(&info->lock) @@ -1363,13 +1421,18 @@ __releases(&info->lock) if (fbidx >= FB_MAX) return -ENODEV; - info = registered_fb[fbidx]; - if (!info) + info = get_framebuffer_info(fbidx); + if (!info) { request_module("fb%d", fbidx); - info = registered_fb[fbidx]; + info = get_framebuffer_info(fbidx); + } if (!info) return -ENODEV; This section of code implies that get_framebuffer_info can return NULL but in that case wouldn't the fb_info->ref_count++ have oopsed? You could add the simple case of if(fb_info) fb_info->ref_count++ to get_framebuffer_info. That should cover it. Thanks, Jack -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/