Messages in this thread Patch in this message | | | Subject | [PATCH 2/4] MTD: create lockless versions of {get,put}_mtd_device | From | Maxim Levitsky <> | Date | Fri, 22 Jan 2010 17:34:16 +0200 |
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>From 628ad1a6a240d444dbd4d6897181daa096ac6226 Mon Sep 17 00:00:00 2001 From: Maxim Levitsky <maximlevitsky@gmail.com> Date: Fri, 22 Jan 2010 15:00:54 +0200 Subject: [PATCH 2/4] 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 <maximlevitsky@gmail.com> --- 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
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