[MTD] add get and put methods

[Linux-MTD Mailing List]

Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=9fe912cea32aec18f860c95e8574410b5892481b
Commit:     9fe912cea32aec18f860c95e8574410b5892481b
Parent:     7799308f34d3c3371a319559687c78c0f2506fcf
Author:     Artem Bityutskiy <dedekind at infradead.org>
AuthorDate: Wed Oct 11 14:52:45 2006 +0300
Committer:  Artem Bityutskiy <dedekind at infradead.org>
CommitDate: Wed Nov 29 17:04:53 2006 +0200

    [MTD] add get and put methods
    
    This patch adds get_device() and put_device() methods to the MTD description
    structure (struct mtd_info). These methods are called by MTD whenever the MTD
    device is get or put. They are needed when the underlying driver is something
    smarter then just flash chip driver, for example UBI.
    
    Signed-off-by: Artem Bityutskiy <dedekind at infradead.org>
---
 drivers/mtd/mtdcore.c   |   37 ++++++++++++++++++++++++++++++-------
 include/linux/mtd/mtd.h |    7 +++++++
 2 files changed, 37 insertions(+), 7 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 06ec9f8..f11f55f 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -214,12 +214,23 @@ struct mtd_info *get_mtd_device(struct m
 			ret = NULL;
 	}
 
-	if (ret && !try_module_get(ret->owner))
+	if (!ret)
+		goto out_unlock;
+
+	if (!try_module_get(ret->owner)) {
+		ret = NULL;
+		goto out_unlock;
+	}
+
+	if (ret->get_device && ret->get_device(ret)) {
+		module_put(ret->owner);
 		ret = NULL;
+		goto out_unlock;
+	}
 
-	if (ret)
-		ret->usecount++;
+	ret->usecount++;
 
+out_unlock:
 	mutex_unlock(&mtd_table_mutex);
 	return ret;
 }
@@ -235,8 +246,8 @@ struct mtd_info *get_mtd_device(struct m
 
 struct mtd_info *get_mtd_device_nm(const char *name)
 {
-	int i;
-	struct mtd_info *mtd = ERR_PTR(-ENODEV);
+	int i, err = -ENODEV;
+	struct mtd_info *mtd = NULL;
 
 	mutex_lock(&mtd_table_mutex);
 
@@ -247,17 +258,27 @@ struct mtd_info *get_mtd_device_nm(const
 		}
 	}
 
-	if (i == MAX_MTD_DEVICES)
+	if (!mtd)
 		goto out_unlock;
 
 	if (!try_module_get(mtd->owner))
 		goto out_unlock;
 
+	if (mtd->get_device) {
+		err = mtd->get_device(mtd);
+		if (err)
+			goto out_put;
+	}
+
 	mtd->usecount++;
+	mutex_unlock(&mtd_table_mutex);
+	return mtd;
 
+out_put:
+	module_put(mtd->owner);
 out_unlock:
 	mutex_unlock(&mtd_table_mutex);
-	return mtd;
+	return ERR_PTR(err);
 }
 
 void put_mtd_device(struct mtd_info *mtd)
@@ -266,6 +287,8 @@ void put_mtd_device(struct mtd_info *mtd
 
 	mutex_lock(&mtd_table_mutex);
 	c = --mtd->usecount;
+	if (mtd->put_device)
+		mtd->put_device(mtd);
 	mutex_unlock(&mtd_table_mutex);
 	BUG_ON(c < 0);
 
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 89e937d..d644e57 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -207,6 +207,13 @@ #define MTD_PROGREGION_CTRLMODE_INVALID(
 
 	struct module *owner;
 	int usecount;
+
+	/* If the driver is something smart, like UBI, it may need to maintain
+	 * its own reference counting. The below functions are only for driver.
+	 * The driver may register its callbacks. These callbacks are not
+	 * supposed to be called by MTD users */
+	int (*get_device) (struct mtd_info *mtd);
+	void (*put_device) (struct mtd_info *mtd);
 };