path: root/drivers/mtd
diff options
authorBrian Norris <>2011-11-07 15:51:05 -0800
committerGreg Kroah-Hartman <>2012-01-18 07:31:51 -0800
commit3e22c678f492f82d5c2fabf1e1e87a59a8021e90 (patch)
tree8a7c7e7035b7565783e305ad7bb08f990075b9b4 /drivers/mtd
parent48a22f1478fb90cad84d9c75dd91cb8ea9750280 (diff)
mtd: mtd_blkdevs: don't increase 'open' count on error path
commit 342ff28f5a2e5aa3236617bd2bddf6c749677ef2 upstream. Some error paths in mtd_blkdevs were fixed in the following commit: commit 94735ec4044a6d318b83ad3c5794e931ed168d10 mtd: mtd_blkdevs: fix error path in blktrans_open But on these error paths, the block device's `dev->open' count is already incremented before we check for errors. This meant that, while the error path was handled correctly on the first time through blktrans_open(), the device is erroneously considered already open on the second time through. This problem can be seen, for instance, when a UBI volume is simultaneously mounted as a UBIFS partition and read through its corresponding gluebi mtdblockX device. This results in blktrans_open() passing its error checks (with `dev->open > 0') without actually having a handle on the device. Here's a summarized log of the actions and results with nandsim: # modprobe nandsim # modprobe mtdblock # modprobe gluebi # modprobe ubifs # ubiattach /dev/ubi_ctrl -m 0 ... # ubimkvol /dev/ubi0 -N test -s 16MiB ... # mount -t ubifs ubi0:test /mnt # ls /dev/mtdblock* /dev/mtdblock0 /dev/mtdblock1 # cat /dev/mtdblock1 > /dev/null cat: can't open '/dev/mtdblock4': Device or resource busy # cat /dev/mtdblock1 > /dev/null CPU 0 Unable to handle kernel paging request at virtual address fffffff0, epc == 8031536c, ra == 8031f280 Oops[#1]: ... Call Trace: [<8031536c>] ubi_leb_read+0x14/0x164 [<8031f280>] gluebi_read+0xf0/0x148 [<802edba8>] mtdblock_readsect+0x64/0x198 [<802ecfe4>] mtd_blktrans_thread+0x330/0x3f4 [<8005be98>] kthread+0x88/0x90 [<8000bc04>] kernel_thread_helper+0x10/0x18 Signed-off-by: Brian Norris <> Signed-off-by: Artem Bityutskiy <> Signed-off-by: David Woodhouse <> Signed-off-by: Greg Kroah-Hartman <>
Diffstat (limited to 'drivers/mtd')
1 files changed, 2 insertions, 1 deletions
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index ca385697446e..bff8d4671ad6 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -215,7 +215,7 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
- if (dev->open++)
+ if (dev->open)
goto unlock;
@@ -235,6 +235,7 @@ static int blktrans_open(struct block_device *bdev, fmode_t mode)
goto error_release;
+ dev->open++;
return ret;