mtd: mtdblock: introduce mtdblks_lock
The mtdblks array and its content are prone to race conditions. Introduce
the mutex mtdblks_lock in order to solve this.
[Amended by Artem Bityutskiy]
Signed-off-by: Matthias Kaehlcke <matthias@kaehlcke.net>
Signed-off-by: Artem Bityutskiy <Artem.Bityutskiy@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdblock.c b/drivers/mtd/mtdblock.c
index 208c6fa..77db5ce 100644
--- a/drivers/mtd/mtdblock.c
+++ b/drivers/mtd/mtdblock.c
@@ -29,6 +29,8 @@
enum { STATE_EMPTY, STATE_CLEAN, STATE_DIRTY } cache_state;
} *mtdblks[MAX_MTD_DEVICES];
+static struct mutex mtdblks_lock;
+
/*
* Cache stuff...
*
@@ -270,15 +272,19 @@
DEBUG(MTD_DEBUG_LEVEL1,"mtdblock_open\n");
+ mutex_lock(&mtdblks_lock);
if (mtdblks[dev]) {
mtdblks[dev]->count++;
+ mutex_unlock(&mtdblks_lock);
return 0;
}
/* 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;
@@ -291,6 +297,7 @@
}
mtdblks[dev] = mtdblk;
+ mutex_unlock(&mtdblks_lock);
DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
@@ -304,6 +311,8 @@
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 +325,9 @@
vfree(mtdblk->cache_data);
kfree(mtdblk);
}
+
+ mutex_unlock(&mtdblks_lock);
+
DEBUG(MTD_DEBUG_LEVEL1, "ok\n");
return 0;
@@ -376,6 +388,8 @@
static int __init init_mtdblock(void)
{
+ mutex_init(&mtdblks_lock);
+
return register_mtd_blktrans(&mtdblock_tr);
}