From patchwork Tue Jun 16 03:23:13 2009 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Zhao, Yakui" X-Patchwork-Id: 30459 Received: from vger.kernel.org (vger.kernel.org [209.132.176.167]) by demeter.kernel.org (8.14.2/8.14.2) with ESMTP id n5G3M526029557 for ; Tue, 16 Jun 2009 03:22:05 GMT Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751372AbZFPDWB (ORCPT ); Mon, 15 Jun 2009 23:22:01 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751959AbZFPDWB (ORCPT ); Mon, 15 Jun 2009 23:22:01 -0400 Received: from mga14.intel.com ([143.182.124.37]:36691 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751372AbZFPDWA (ORCPT ); Mon, 15 Jun 2009 23:22:00 -0400 Received: from azsmga001.ch.intel.com ([10.2.17.19]) by azsmga102.ch.intel.com with ESMTP; 15 Jun 2009 20:22:03 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.42,225,1243839600"; d="scan'208";a="154836028" Received: from yakui_zhao.sh.intel.com (HELO [10.239.13.158]) ([10.239.13.158]) by azsmga001.ch.intel.com with ESMTP; 15 Jun 2009 20:22:02 -0700 Subject: [PATCH]: ACPI: Add the reference count to avoid unloading ACPI video bus twice From: yakui_zhao To: lenb@kernel.org Cc: linux-acpi@vger.kernel.org Organization: Intel Open Source Technology Center Date: Tue, 16 Jun 2009 11:23:13 +0800 Message-Id: <1245122593.3583.117.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.22.1 (2.22.1-2.fc9) Sender: linux-acpi-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-acpi@vger.kernel.org From: Zhao Yakui Sometimes both acpi video and i915 driver are compiled as modules. And there exists the strict dependency between the two drivers. The acpi video bus will be unloaded in course of unloading the i915 driver. If we unload the acpi video driver, then the kernel oops will be triggered. Add the reference count to avoid unloading the ACPI video bus twice. The reference count should be checked before unregistering the acpi video bus. If the reference count is already zero, it won't unregister it again. And after the acpi video bus is already unregistered, the reference count will be set to zero. http://bugzilla.kernel.org/show_bug.cgi?id=13396 Signed-off-by: Zhao Yakui Acked-by: Zhang Rui --- drivers/acpi/video.c | 41 +++++++++++++++++++++++++++++------ drivers/gpu/drm/i915/i915_opregion.c | 2 - include/acpi/video.h | 4 +-- 3 files changed, 38 insertions(+), 9 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Index: linux-2.6/drivers/acpi/video.c =================================================================== --- linux-2.6.orig/drivers/acpi/video.c 2009-06-16 10:25:12.000000000 +0800 +++ linux-2.6/drivers/acpi/video.c 2009-06-16 11:09:57.000000000 +0800 @@ -76,6 +76,7 @@ static int brightness_switch_enabled = 1; module_param(brightness_switch_enabled, bool, 0644); +static int register_count = 0; static int acpi_video_bus_add(struct acpi_device *device); static int acpi_video_bus_remove(struct acpi_device *device, int type); static int acpi_video_resume(struct acpi_device *device); @@ -2318,6 +2319,13 @@ int acpi_video_register(void) { int result = 0; + if (register_count) { + /* + * if the function of acpi_video_register is already called, + * don't register the acpi_vide_bus again and return no error. + */ + return 0; + } acpi_video_dir = proc_mkdir(ACPI_VIDEO_CLASS, acpi_root_dir); if (!acpi_video_dir) @@ -2329,10 +2337,35 @@ return -ENODEV; } + /* + * When the acpi_video_bus is loaded successfully, increase + * the counter reference. + */ + register_count = 1; + return 0; } EXPORT_SYMBOL(acpi_video_register); +void acpi_video_unregister(void) +{ + if (!register_count) { + /* + * If the acpi video bus is already unloaded, don't + * unload it again and return directly. + */ + return; + } + acpi_bus_unregister_driver(&acpi_video_bus); + + remove_proc_entry(ACPI_VIDEO_CLASS, acpi_root_dir); + + register_count = 0; + + return; +} +EXPORT_SYMBOL(acpi_video_unregister); + /* * This is kind of nasty. Hardware using Intel chipsets may require * the video opregion code to be run first in order to initialise @@ -2350,16 +2383,12 @@ return acpi_video_register(); } -void acpi_video_exit(void) +static void __exit acpi_video_exit(void) { - - acpi_bus_unregister_driver(&acpi_video_bus); - - remove_proc_entry(ACPI_VIDEO_CLASS, acpi_root_dir); + acpi_video_unregister(); return; } -EXPORT_SYMBOL(acpi_video_exit); module_init(acpi_video_init); module_exit(acpi_video_exit); Index: linux-2.6/drivers/gpu/drm/i915/i915_opregion.c =================================================================== --- linux-2.6.orig/drivers/gpu/drm/i915/i915_opregion.c 2009-06-16 10:25:12.000000000 +0800 +++ linux-2.6/drivers/gpu/drm/i915/i915_opregion.c 2009-06-16 10:29:50.000000000 +0800 @@ -419,7 +419,7 @@ return; if (!suspend) - acpi_video_exit(); + acpi_video_unregister(); opregion->acpi->drdy = 0; Index: linux-2.6/include/acpi/video.h =================================================================== --- linux-2.6.orig/include/acpi/video.h 2009-06-16 10:25:12.000000000 +0800 +++ linux-2.6/include/acpi/video.h 2009-06-16 11:07:43.000000000 +0800 @@ -3,10 +3,10 @@ #if (defined CONFIG_ACPI_VIDEO || defined CONFIG_ACPI_VIDEO_MODULE) extern int acpi_video_register(void); -extern int acpi_video_exit(void); +extern void acpi_video_unregister(void); #else static inline int acpi_video_register(void) { return 0; } -static inline void acpi_video_exit(void) { return; } +static inline void acpi_video_unregister(void) { return; } #endif #endif