[LTP] Request for Modification of test cases

[Li Wang]

Hi Gulam,

On Sat, Jul 6, 2024 at 3:48 AM Gulam Mohamed via ltp <ltp@lists.linux.it>
wrote:

> Hi Team,
>
>     This is regarding the change in kernel behavior about the way the loop
> device is detached.
>
>               Current behavior
>               -----------------------
>               When the LOOP_CLR_FD ioctl command is sent to detach the
> loop device, the earlier behavior was that the loop     device used to be
> detached at that instance itself if there was a single opener only. If
>                there were multiple openers of the loop device, the
> behavior was to defer the detach operation at the last close of the device.
>
>               New behavior
>               ------------------
>               As per the new behavior, irrespective of whether there are
> any openers of the loop device or not, the detach operation is deferred to
> the last close of the device. This was done to address an issue, due
>               to race coditions, recently we had in kernel.
>
>               With the new kernel behavior in place, some of the LTP test
> cases in "testcases/kernel/syscalls/ioctl/" are failing as the device is
> closed at the end of the test and the test cases are expecting for the
>                results which can occur after the device is detached. Some
> of the test cases which are failing are:
>
>               1. ioctl04, ioctl05, ioctl06, ioctl07, ioctl09
>               2. ioctl_loop01, ioctl_loop02, ioctl_loop03, ioctl_loop04,
> ioctl_loop05, ioctl_loop06, ioctl_loop07
>
>               The main root cause of the most of the test failures, is the
> function "tst_detach_device_by_fd()" where the function is expecting error
> ENXIO which is returned only after the device is detached. But
>               detach, as per new behavior, happens only after the last
> close (i.e after this function is returned), the test will fail with
> following error:
>
>               "ioctl(/dev/loop0, LOOP_CLR_FD, 0) no ENXIO for too long"
>
>               Similarly, some other test cases are expecting results which
> are returned after the detach operation, but as the detach did not happen,
> unexpected values are returned resulting in the test failure.
>
>               So, can LTP maintainers team change the impacted test cases
> to accommodate the new behavior of kernel for the detach operation of the
> loop device?
>


Thanks for highlighting the issue, can you tell which kernel version
(commit ?)
introduced that change, then we could adjust the test against the different
kernels.


-- 
Regards,
Li Wang