In some environments an attempt to load ltp_tbio.ko module will
result in a kernel panic.
It happens, because after the module is loaded (add_disk(tbio_dev.gd) in
tbio_init() is executed), one or more ioctl() calls are issued to the newly
created block device. However, when ioctl() is called, there is no (yet) file
/dev/tbio created. Therefore, in tbio_ioctl():
tbio_dev.bdev = blkdev_get_by_path(
DEVICE_NAME, FMODE_READ | FMODE_WRITE, NULL);
returns -ENODEV, i.e. tbio_dev.bdev == -ENODEV, and it produces a kernel panic
at:
blkdev_put(tbio_dev.bdev, FMODE_READ | FMODE_WRITE);
We could introduce error checking here like this:
if (IS_ERR(tbio_dev.bdev))
return PTR_ERR(tbio_dev.bdev);
but I assume it would be better to return the previous logic, before commit
69d3b32681 "device-drivers: tbio: fixes", i.e. where tbio_dev.bdev is assigned
in tbio_open().
Signed-off-by: Stanislav Kholmanskikh <[email protected]>
---
.../device-drivers/tbio/tbio_kernel/ltp_tbio.c | 8 +++-----
1 files changed, 3 insertions(+), 5 deletions(-)
diff --git a/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
b/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
index 5198b82..4e38fe7 100644
--- a/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
+++ b/testcases/kernel/device-drivers/tbio/tbio_kernel/ltp_tbio.c
@@ -376,14 +376,11 @@ static int tbio_ioctl(struct block_device *blk, fmode_t
mode,
{
int err = 0;
- tbio_dev.bdev = blkdev_get_by_path(
- DEVICE_NAME, FMODE_READ | FMODE_WRITE, NULL);
-
switch (cmd) {
case LTP_TBIO_DO_IO:
prk_info("TEST-CASE: LTP_TBIO_DO_IO:");
err = tbio_io(tbio_dev.bdev, (struct tbio_interface *)arg);
- break;
+ break;
case LTP_TBIO_CLONE:
prk_info("TEST-CASE: LTP_TBIO_CLONE:");
err = test_bio_clone();
@@ -412,7 +409,6 @@ static int tbio_ioctl(struct block_device *blk, fmode_t
mode,
}
prk_info("TEST-CASE DONE");
- blkdev_put(tbio_dev.bdev, FMODE_READ | FMODE_WRITE);
return err;
}
@@ -475,6 +471,8 @@ static void tbio_request(struct request_queue *q)
static int tbio_open(struct block_device *blk, fmode_t mode)
{
+ tbio_dev.bdev = blk;
+
return 0;
}
--
1.7.1
------------------------------------------------------------------------------
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