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

[Xiao Yang]

On 2020/3/30 12:39, Li Wang wrote:
> Hi Xiao,
>
> On Sun, Mar 29, 2020 at 1:36 PM Xiao Yang <yangx.jy@cn.fujitsu.com
> <mailto:yangx.jy@cn.fujitsu.com>> wrote:
>
>     On 2020/3/28 11:42, Petr Vorel wrote:
>      > Hi Xiao,
>      >
>      >> On 3/28/20 5:39 AM, Petr Vorel wrote:
>      >>> + There is a double check (first in
>      >>> .needs_cmds, then in SAFE_RUN_CMD()), maybe that's not needed.
>      >
>      >> Hi Petr,
>      >
>      >> Why do you need the duplicate .needs_cmds flag?(it introduces
>     the double
>      >> check as you said)
>      >
>      >> Usually, all tests run commands by tst_run_cmd()/SAFE_RUN_CMD()
>     and they can
>      >> report TCONF
>      >
>      >> by passing TST_RUN_CMD_CHECK_CMD so it is fair to be a part of
>      >> tst_run_cmd()/SAFE_RUN_CMD().
>      >
>      > Thanks for your review.
>      > I guess Cyril will prefer .needs_cmds, as it can be parsed -
>     metadata project:
>      > https://people.kernel.org/metan/towards-parallel-kernel-test-runs
>      > https://github.com/metan-ucw/ltp/tree/master/docparse
>     Hi Petr，
>
>     Thank you for sharing these info.
>     Does Cyril want to get metadata from struct tst_test directly?
>
>     How about the rough design?
>     1) .needs_cmds only saves the required commands.(doesn't do any check)
>     2) pass the corresponding member of .needs_cmds to
>     tst_run_cmd()/SAFE_RUN_CMD()(do check in these functions).
>     For example:
>     ----------------------------------------------
>     # grep tst_needs_cmds include/tst_cmd.h
>     extern const char *const *tst_needs_cmds;
>
>     # grep -B1 tst_needs_cmds lib/tst_test.c
>
>     const char *const *tst_needs_cmds;
>     --
>     if (tst_test->needs_cmds)
>     tst_needs_cmds = tst_test->needs_cmds;
>
>     # 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.

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