Re: [Qemu-block] [PATCH v3 7/7] iotests: Set read-zeroes on in null block driver for Valgrind

[Andrey Shinkevich]

On 28/06/2019 16:46, Andrey Shinkevich wrote:
> The Valgrind tool reports about the uninitialised buffer 'buf'
> instantiated on the stack of the function guess_disk_lchs().
> It is revealed in the tests 051, 186, 227 and 240.
> Pass 'read-zeroes=on' to the null block driver in the mentioned tests
> to make them deterministic.
> The output of the tests above now includes the parameter 'read-zeroes'.
> So, the benchmark output files are being changed too.
> 
> Suggested-by: Kevin Wolf <address@hidden>
> Signed-off-by: Andrey Shinkevich <address@hidden>
> ---
>   tests/qemu-iotests/051        |  10 +--
>   tests/qemu-iotests/051.pc.out |  10 +--
>   tests/qemu-iotests/186        |  20 +++---
>   tests/qemu-iotests/186.out    | 152 
> +++++++++++++++++++++---------------------
>   tests/qemu-iotests/227        |   4 +-
>   tests/qemu-iotests/227.out    |   4 +-
>   tests/qemu-iotests/240        |   8 +--
>   7 files changed, 104 insertions(+), 104 deletions(-)
> 

The Valgrind rebukes the uninitialized buffer in the find_image_format() 
of block.c when test 155 runs.
I would like to modify the python code in the mentioned test by 
replacing the backing file name:

target_backing = 'null-co://'

with

target_backing = 'json:{"read-zeroes": true, "driver": "null-co"}'

Is that the right and elegant way to do?
If so, I will add it to the next version.

Andrey

-- 
With the best regards,
Andrey Shinkevich