msync01：testcase need revisit

[huilinzh]

Source code: kernel/syscalls/msync/msync01.c

If run the command "msync01" without any options, the test tries to do the following:

1. open/create a file
2. mmap this file
3. memset part of the mapped memory to "1" for this file
4. msync the mapped memory to this file
5. lseek the file to the position, which is memset to "1" in above step 3.
6. read the file and compare the value

In step 4, msync is called with flag MS_ASYNC. This flag means an update be scheduled, but the call to msync returns immediately. That's it doesn't guarantee the synchronization is completed before the msync() return. So the comparation in
step 6 may succeed or fail. The test result can't be expected to be always successful.

[metan-ucw]

Good catch, the MS_ASYNC should be replaced by MS_SYNC. Can you send a patch?

[huilinzh]

Please see the patch here.

0001-fix-Update-msync01.c.patch

[metan-ucw]

The patch looks good, but is missing the Signed-off-by line, see: https://docs.kernel.org/process/submitting-patches.html#developer-s-certificate-of-origin-1-1

Also if possible we prefer patches send to our mailing list: https://linux-test-project.readthedocs.io/en/latest/developers/setup_mailinglist.html

[huilinzh]

OK. The patch was sent to the LTP mailing list.