diff options
Diffstat (limited to 'sys/kern/vfs_export.c')
| -rw-r--r-- | sys/kern/vfs_export.c | 86 |
1 files changed, 85 insertions, 1 deletions
diff --git a/sys/kern/vfs_export.c b/sys/kern/vfs_export.c index 254e9a7..c978bbf 100644 --- a/sys/kern/vfs_export.c +++ b/sys/kern/vfs_export.c @@ -36,7 +36,7 @@ * SUCH DAMAGE. * * @(#)vfs_subr.c 8.31 (Berkeley) 5/26/95 - * $Id: vfs_subr.c,v 1.113 1997/11/12 05:42:15 julian Exp $ + * $Id: vfs_subr.c,v 1.114 1997/11/22 08:35:39 bde Exp $ */ /* @@ -1207,6 +1207,7 @@ vclean(vp, flags, p) * Done with purge, notify sleepers of the grim news. */ vp->v_op = dead_vnodeop_p; + vn_pollgone(vp); vp->v_tag = VT_NON; vp->v_flag &= ~VXLOCK; if (vp->v_flag & VXWANT) { @@ -2111,3 +2112,86 @@ vbusy(vp) simple_unlock(&vnode_free_list_slock); vp->v_flag &= ~VFREE; } + +/* + * Record a process's interest in events which might happen to + * a vnode. Because poll uses the historic select-style interface + * internally, this routine serves as both the ``check for any + * pending events'' and the ``record my interest in future events'' + * functions. (These are done together, while the lock is held, + * to avoid race conditions.) + */ +int +vn_pollrecord(vp, p, events) + struct vnode *vp; + struct proc *p; + short events; +{ + simple_lock(&vp->v_pollinfo.vpi_lock); + if (vp->v_pollinfo.vpi_revents & events) { + /* + * This leaves events we are not interested + * in available for the other process which + * which presumably had requested them + * (otherwise they would never have been + * recorded). + */ + events &= vp->v_pollinfo.vpi_revents; + vp->v_pollinfo.vpi_revents &= ~events; + + simple_unlock(&vp->v_pollinfo.vpi_lock); + return events; + } + vp->v_pollinfo.vpi_events |= events; + selrecord(p, &vp->v_pollinfo.vpi_selinfo); + simple_unlock(&vp->v_pollinfo.vpi_lock); + return 0; +} + +/* + * Note the occurrence of an event. If the VN_POLLEVENT macro is used, + * it is possible for us to miss an event due to race conditions, but + * that condition is expected to be rare, so for the moment it is the + * preferred interface. + */ +void +vn_pollevent(vp, events) + struct vnode *vp; + short events; +{ + simple_lock(&vp->v_pollinfo.vpi_lock); + if (vp->v_pollinfo.vpi_events & events) { + /* + * We clear vpi_events so that we don't + * call selwakeup() twice if two events are + * posted before the polling process(es) is + * awakened. This also ensures that we take at + * most one selwakeup() if the polling process + * is no longer interested. However, it does + * mean that only one event can be noticed at + * a time. (Perhaps we should only clear those + * event bits which we note?) XXX + */ + vp->v_pollinfo.vpi_events = 0; /* &= ~events ??? */ + vp->v_pollinfo.vpi_revents |= events; + selwakeup(&vp->v_pollinfo.vpi_selinfo); + } + simple_unlock(&vp->v_pollinfo.vpi_lock); +} + +/* + * Wake up anyone polling on vp because it is being revoked. + * This depends on dead_poll() returning POLLHUP for correct + * behavior. + */ +void +vn_pollgone(vp) + struct vnode *vp; +{ + simple_lock(&vp->v_pollinfo.vpi_lock); + if (vp->v_pollinfo.vpi_events) { + vp->v_pollinfo.vpi_events = 0; + selwakeup(&vp->v_pollinfo.vpi_selinfo); + } + simple_unlock(&vp->v_pollinfo.vpi_lock); +} |
