While fixing the looping of a thread while devfs vnode is reclaimed,

r179247 introduced a possibility of devfs_allocv() returning spurious
ENOENT. If the vnode is selected by vnlru daemon for reclamation, then
devfs_allocv() can get ENOENT from vget() due to devfs_close() dropping
vnode lock around the call to cdevsw d_close method.

Use LK_RETRY in the vget() call, and do some part of the devfs_reclaim()
work in devfs_allocv(), clearing vp->v_data and de->de_vnode. Retry the
allocation of the vnode, now with de->de_vnode == NULL.

The check vp->v_data == NULL at the start of devfs_close() cannot be
affected by the change, since vnode lock must be held while VI_DOOMED
is set, and only dropped after the check.

Reported and tested by:	Kohji Okuno <okuno.kohji jp panasonic com>
Reviewed by:	attilio
MFC after:	3 weeks

0 files changed, 0 insertions, 0 deletions