Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932893Ab0AFVpz (ORCPT ); Wed, 6 Jan 2010 16:45:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756314Ab0AFVpx (ORCPT ); Wed, 6 Jan 2010 16:45:53 -0500 Received: from mail-fx0-f225.google.com ([209.85.220.225]:44707 "EHLO mail-fx0-f225.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752531Ab0AFVpw (ORCPT ); Wed, 6 Jan 2010 16:45:52 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=subject:from:to:cc:in-reply-to:references:content-type:date :message-id:mime-version:x-mailer:content-transfer-encoding; b=wB6RPRtJ34mRj/IzooxF1gWkwt862zrxiOEI+J/Q5IZvlAol+diqSHY5zCwMhrNTbE PWfn75ZyZO7ljOEJ0f5lKgrbUhnd0A7pNAmjGiAAOg6G0NzF7ZFUM4e++HULDt4uNnuI IoDJCSeEgzuTG+jsk1kmFxvnySKIW4frOBrio= Subject: [PATCH 2/9] MTD: create lockless versions of {get,put}_mtd_device From: Maxim Levitsky To: linux-kernel Cc: linux-mtd , Alex Dubov , joern In-Reply-To: <1262814216.14552.22.camel@maxim-laptop> References: <1262814216.14552.22.camel@maxim-laptop> Content-Type: text/plain; charset="UTF-8" Date: Wed, 06 Jan 2010 23:45:48 +0200 Message-ID: <1262814348.14552.24.camel@maxim-laptop> Mime-Version: 1.0 X-Mailer: Evolution 2.28.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3220 Lines: 127 >From 10333e0ed6dc7b176f2dfce04f08572f9e1b04ce Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Tue, 5 Jan 2010 22:29:31 +0200 Subject: [PATCH 2/9] MTD: create lockless versions of {get,put}_mtd_device This will be used to resolve deadlock in block translation layer --- drivers/mtd/mtdcore.c | 55 +++++++++++++++++++++++++++------------------- include/linux/mtd/mtd.h | 3 +- 2 files changed, 34 insertions(+), 24 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 738e329..e9daf87 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -454,27 +454,30 @@ struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num) ret = NULL; } - if (!ret) - goto out_unlock; - - if (!try_module_get(ret->owner)) - goto out_unlock; - - if (ret->get_device) { - err = ret->get_device(ret); - if (err) - goto out_put; - } + if (!ret || (err = __get_mtd_device(ret))) + ret = ERR_PTR(err); - ret->usecount++; mutex_unlock(&mtd_table_mutex); return ret; +} -out_put: - module_put(ret->owner); -out_unlock: - mutex_unlock(&mtd_table_mutex); - return ERR_PTR(err); + +int __get_mtd_device(struct mtd_info *mtd) +{ + int err; + + if (!try_module_get(mtd->owner)) + return -ENODEV; + + if (mtd->get_device) { + + if ((err = mtd->get_device(mtd))) { + module_put(mtd->owner); + return err; + } + } + mtd->usecount++; + return 0; } /** @@ -525,18 +528,22 @@ out_unlock: void put_mtd_device(struct mtd_info *mtd) { - int c; - mutex_lock(&mtd_table_mutex); - c = --mtd->usecount; - if (mtd->put_device) - mtd->put_device(mtd); + __put_mtd_device(mtd); mutex_unlock(&mtd_table_mutex); - BUG_ON(c < 0); module_put(mtd->owner); } +void __put_mtd_device(struct mtd_info *mtd) +{ + --mtd->usecount; + BUG_ON(mtd->usecount < 0); + + if (mtd->put_device) + mtd->put_device(mtd); +} + /* default_mtd_writev - default mtd writev method for MTD devices that * don't implement their own */ @@ -570,7 +577,9 @@ EXPORT_SYMBOL_GPL(add_mtd_device); EXPORT_SYMBOL_GPL(del_mtd_device); EXPORT_SYMBOL_GPL(get_mtd_device); EXPORT_SYMBOL_GPL(get_mtd_device_nm); +EXPORT_SYMBOL_GPL(__get_mtd_device); EXPORT_SYMBOL_GPL(put_mtd_device); +EXPORT_SYMBOL_GPL(__put_mtd_device); EXPORT_SYMBOL_GPL(register_mtd_user); EXPORT_SYMBOL_GPL(unregister_mtd_user); EXPORT_SYMBOL_GPL(default_mtd_writev); diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h index 0f32a9b..662d747 100644 --- a/include/linux/mtd/mtd.h +++ b/include/linux/mtd/mtd.h @@ -290,8 +290,9 @@ extern int add_mtd_device(struct mtd_info *mtd); extern int del_mtd_device (struct mtd_info *mtd); extern struct mtd_info *get_mtd_device(struct mtd_info *mtd, int num); +extern int __get_mtd_device(struct mtd_info *mtd); +extern void __put_mtd_device(struct mtd_info *mtd); extern struct mtd_info *get_mtd_device_nm(const char *name); - extern void put_mtd_device(struct mtd_info *mtd); -- 1.6.3.3 -- 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/