From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from fg-out-1718.google.com ([72.14.220.159]) by bombadil.infradead.org with esmtp (Exim 4.69 #1 (Red Hat Linux)) id 1NUmRs-0004CF-1y for linux-mtd@lists.infradead.org; Tue, 12 Jan 2010 19:30:44 +0000 Received: by fg-out-1718.google.com with SMTP id e21so267421fga.0 for ; Tue, 12 Jan 2010 11:30:38 -0800 (PST) Subject: [PATCH 2/9] MTD: create lockless versions of {get,put}_mtd_device From: Maxim Levitsky To: linux-kernel In-Reply-To: <1263324518.6236.18.camel@maxim-laptop> References: <1263324518.6236.18.camel@maxim-laptop> Content-Type: text/plain; charset="UTF-8" Date: Tue, 12 Jan 2010 21:30:34 +0200 Message-ID: <1263324634.6236.20.camel@maxim-laptop> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Cc: joern , linux-mtd , Alex Dubov List-Id: Linux MTD discussion mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , >>From 1531249dd2c0e33d727ed8cbd0719eb4e9af2266 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky Date: Fri, 8 Jan 2010 15:51:22 +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. Signed-off-by: Maxim Levitsky --- drivers/mtd/mtdcore.c | 61 ++++++++++++++++++++++++++++++----------------- include/linux/mtd/mtd.h | 3 +- 2 files changed, 41 insertions(+), 23 deletions(-) diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c index 87ff83f..96b4a05 100644 --- a/drivers/mtd/mtdcore.c +++ b/drivers/mtd/mtdcore.c @@ -454,27 +454,38 @@ 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) { + ret = ERR_PTR(err); + goto out; } - ret->usecount++; + err = __get_mtd_device(ret); + if (err) + ret = ERR_PTR(err); +out: 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) { + + err = mtd->get_device(mtd); + + if (err) { + module_put(mtd->owner); + return err; + } + } + mtd->usecount++; + return 0; } /** @@ -525,18 +536,22 @@ 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 +585,9 @@ 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