On Tue, May 03, 2016 at 12:20:41PM +0000, Emmanuel Dreyfus wrote:
> Well, I need you to explain me what happens in sys_flock() then.
> Is it a bug?
> error = VOP_ADVLOCK(vp, fp, F_UNLCK, &lf, F_FLOCK);
>
> fp is struct file. Same thing happens in open_setfp() and closef()
sys_flock() is for BSD flock(2) advisory file locking. There is no
mandatory BSD file locking.
The Linux mandatory-locking.txt that you cited clearly states that it
applies to fcntl(2)/lockf(2) locking.
If you look into lf_advlock() you notice:
if (lock->lf_flags & F_POSIX) {
KASSERT(curproc == (struct proc *)ap->a_id);
}
lock->lf_id = ap->a_id;
I.e. for POSIX/fcntl(2) locking it the owner must be curproc.
Are you looking for sys_lockf? That doesn't exist because
libc/gen/lockf.c is a thin wrapper around fcntl(2).
--chris
