[LTP] [PATCH v3 3/3] syscalls/pipe2_03: Add new test for pipe2 O_DIRECT flag

[Yang Xu]

Hi Li

> Hi Xu,
> 
> Yang Xu <xuyang2018.jy@cn.fujitsu.com 
> <mailto:xuyang2018.jy@cn.fujitsu.com>> wrote:
> 
>     ...
>      >
>      > # ./pipe2_03
>      > tst_test.c:1246: INFO: Timeout per run is 0h 05m 00s
>      > pipe2_03.c:48: PASS: Each write(2) uses a separate packet
>      > pipe2_03.c:61: PASS: Each read(2) reads a separate packet
>      > pipe2_03.c:81: PASS: write(higner than PIPE_BUF) split into
>     multiple packet
>      > pipe2_03.c:108: FAIL: the excess bytes in the packet is discarded by
>      > read, expect 1 got 1%A
>     Even I use one fork and exit(0), I don't meet this problem. Or, I miss
>     something?
> 
> 
> I think I got the point.
> 
> In your test code for pipe2(), you didn't use pipe in the correct way. 
> Even that we define the fds[2] as a global variable, there still have a 
> new copy for fds[2] in the child process, we should close one of the 
> pipes in child and parent to make the connection is built 
> correspondingly, then that will work normally for us.
> 
> I suggest redesigning some of the test structs. What do you think?
Yes.
> 
> Fyi: 
> https://github.com/linux-test-project/ltp/blob/master/testcases/kernel/syscalls/pipe/pipe02.c
In principle, we should use the following format
step1      pipe(fds);
step2      SAFE_FORK();
       child process
step3         close one fd and do something
       parent process
step4         close another fd and do something

Also, we should not do write opeartion in step 1~2, otherwise child 
process will inherit data.
> 
> -- 
> Regards,
> Li Wang