[LTP] [PATCH 0/6] C API: .needs_cmds and SAFE_RUN_CMD()

[Xiao Yang]

On 2020/3/30 15:12, Petr Vorel wrote:
> Hi Xiao,
>
>>>      # grep -A2 'needs_cmds' testcases/kernel/syscalls/add_key/add_key05.c
>>>      const char *const cmd_useradd[] = {tst_needs_cmds[0], username, NULL};
>>>      int rc;
>
>>> I don't see any advantage of involving this struct in a test case, and
>>> it also makes things more complicated.
>> Hi Li,
>
>> In fact, I perfer to remove .need_cmd and use tst_run_cmd with/without
>> TST_RUN_CMD_CHECK_CMD directly.
>> But I am not sure if it is necessary to keep .need_cmd for metadata project.
>> I think we can generate json about resouce by reading struct tst_test or
>> other ways.
>
> not sure if you mean removing .needs_cmds entirely or just for
> copy_file_range02.c. or some other test. I rewritten the original patchset
> because Cyril suggested .needs_cmds implementation:
>
> 	"Actually I would like to avoid exposing the function to the tests and
> 	force people to use the .needs_cmds instead in order to have a proper
> 	metadata." [1]
>
>
Hi Petr,

Thanks a lot for your explanation.

I want to remove .needs_cmds entirely before but it may be helpful to 
get metadata about command.

Thanks,
Xiao Yang
> IMHO parsing struct members is easier to get metadata than searching for
> various functions to be used, so I understand Cyril's intention. Cyril explains
> this on his blog posts (I've noticed [2], but it's also in [3]: "this
> arrangement also helps to export the test metadata into a machine parsable
> format").
>
> Kind regards,
> Petr
>
>> Thanks,
>> Xiao Yang
>
>
>>> IMO, the '.needs_cmds' should do check and guarantee all the cmds exist.
>>> That's a hard requirement for the test. If a situation that the commands
>>> are only part of the requirement(soft), we could avoid using
>>> '.needs_cmds' in the test and just calling tst_run_cmd() without passing
>>> TST_RUN_CMD_CHECK_CMD flag. This satisfies most situations we have, it
>>> is safe enough and choosable for people.
>
>>> Or maybe I'm wrong here too:).
>
>>> --
>>> Regards,
>>> Li Wang
>
>
> Kind regards,
> Petr
>
> [1] https://lists.linux.it/pipermail/ltp/2020-March/016233.html
> [2] https://people.kernel.org/metan/towards-parallel-kernel-test-runs
> [3] https://people.kernel.org/metan/the-ltp-test-driver-model
>
>
> .
>