[PATCH] mtdblock: introduce mtdblks_lock

Matthias Kaehlcke
2009-07-14T20:04:44Z

The mtdblks array and its content are prone to race conditions. Introduce
the mutex mtdblks_lock in order to solve this.

Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
---
drivers/mtd/mtdblock.c | 17 ++++++++++++++++-
1 files changed, 16 insertions(+), 1 deletions(-)

diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
index 208c6fa..ca0c6b8 100644
--- a/drivers/mtd/mtdblock.c
+++ b/drivers/mtd/mtdblock.c
@@ -29,6 +29,8 @@ static struct mtdblk_dev {
enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
} *mtdblks[MAX_MTD_DEVICES];

+static struct mutex mtdblks_lock;
+
/*
* Cache stuff...
*
@@ -270,6 +272,8 @@ static int mtdblock_open(struct mtd_blktrans_dev *mbd)

DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");

+ mutex_lock(&mtdblks_lock);
+
if (mtdblks[dev]) {
mtdblks[dev]->count++;
return 0;
@@ -277,8 +281,10 @@ static int mtdblock_open(struct mtd_blktrans_dev *mbd)

/* OK, it's not open. Create cache info for it */
mtdblk = kzalloc(sizeof(struct mtdblk_dev), GFP_KERNEL);
- if (!mtdblk)
+ if (!mtdblk) {
+ mutex_unlock(&mtdblks_lock);
return -ENOMEM;
+ }

mtdblk->count = 1;
mtdblk->mtd = mtd;
@@ -292,6 +298,8 @@ static int mtdblock_open(struct mtd_blktrans_dev *mbd)

mtdblks[dev] = mtdblk;

+ mutex_unlock(&mtdblks_lock);
+
DEBUG(MTD_DEBUG_LEVEL1, "ok\n");

return 0;
@@ -304,6 +312,8 @@ static int mtdblock_release(struct mtd_blktrans_dev *mbd)

DEBUG(MTD_DEBUG_LEVEL1, "mtdblock_release\n");

+ mutex_lock(&mtdblks_lock);
+
mutex_lock(&mtdblk->cache_mutex);
write_cached_data(mtdblk);
mutex_unlock(&mtdblk->cache_mutex);
@@ -316,6 +326,9 @@ static int mtdblock_release(struct mtd_blktrans_dev *mbd)
vfree(mtdblk->cache_data);
kfree(mtdblk);
}
+
+ mutex_unlock(&mtdblks_lock);
+
DEBUG(MTD_DEBUG_LEVEL1, "ok\n");

return 0;
@@ -376,6 +389,8 @@ static struct mtd_blktrans_ops mtdblock_tr = {

static int __init init_mtdblock(void)
{
+ mutex_init(&mtdblks_lock);
+
return register_mtd_blktrans(&mtdblock_tr);
}

--
1.6.3.1