Question about fcntl64

Hongzhi, Song
Wed Sep 12 14:20:00 GMT 2018

Hi all,

I met a problem with one of ltp testcase, fcntl34, on qemux86.

Testcase source code: ltp/testcases/kernel/syscalls/fcntl/fcntl34.c

In function 'thread_fn_01', struct flock64 lck.l_len is set '1'.

thread_fn_01 ---> SAFE_FCNTL(fd, F_OFD_SETLKW, &lck) ---> fcntl64

But I used 'strace -f ./fcntl34' to trace 'fcntl64' syscall, I found 
that 'lck.l_len'

is set '0'.

The result of strace: note "---> <---"

fcntl64(6, F_OFD_SETLKW, {l_type=F_WRLCK, l_whence=SEEK_SET, l_start=0, 
--- > l_len=0 <---}

I can't find that where dose l_len is set '0'.

So, can someone tell me than why l_len is change to '0' which is set '1' 



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