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

[Yang Xu]

Hi Li


> 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 
BTW, pipe02.c can use SAFE_PIPE macro and remove  UCLINUX ifdef.
>>
> 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
> 
> 
>