[Bug 272367] openat(..., O_NONBLOCK | O_EXLOCK) may wrongly return EAGAIN

https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=272367

Mateusz Guzik <mjg@FreeBSD.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |mjg@FreeBSD.org

--- Comment #1 from Mateusz Guzik <mjg@FreeBSD.org> ---
Quick look suggests this is about the P_ADVLOCK flag, which to my reading is
not being set for the child. Then fdclosexec -> ... -> closef fails to take
action here:

        if (fp->f_type == DTYPE_VNODE) {
                vp = fp->f_vnode;
                if ((td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
                        lf.l_whence = SEEK_SET;
                        lf.l_start = 0;
                        lf.l_len = 0;
                        lf.l_type = F_UNLCK;
                        (void) VOP_ADVLOCK(vp, (caddr_t)td->td_proc->p_leader,
                            F_UNLCK, &lf, F_POSIX);
                }

I don't know what the real semantics are supposed to be here. If any close by
*anyone* is supposed to do the unlock, then this should be patched to something
like this:

diff --git a/sys/kern/kern_descrip.c b/sys/kern/kern_descrip.c
index 908c3352514b..fc03137f6c24 100644
--- a/sys/kern/kern_descrip.c
+++ b/sys/kern/kern_descrip.c
@@ -2790,7 +2790,7 @@ closef(struct file *fp, struct thread *td)
         */
        if (fp->f_type == DTYPE_VNODE) {
                vp = fp->f_vnode;
-               if ((td->td_proc->p_leader->p_flag & P_ADVLOCK) != 0) {
+               if ((fp->f_flag & FHASLOCK) != 0) {
                        lf.l_whence = SEEK_SET;
                        lf.l_start = 0;
                        lf.l_len = 0;

-- 
You are receiving this mail because:
You are the assignee for the bug.