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Index: head/sys/net/if_tun.c
===================================================================
--- head/sys/net/if_tun.c
+++ head/sys/net/if_tun.c
@@ -81,16 +81,10 @@
#define TUN_RWAIT 0x0040
#define TUN_ASYNC 0x0080
#define TUN_IFHEAD 0x0100
+#define TUN_DYING 0x0200
#define TUN_READY (TUN_OPEN | TUN_INITED)
- /*
- * XXXRW: tun_pid is used to exclusively lock /dev/tun. Is this
- * actually needed? Can we just return EBUSY if already open?
- * Problem is that this involved inherent races when a tun device
- * is handed off from one process to another, as opposed to just
- * being slightly stale informationally.
- */
pid_t tun_pid; /* owning pid */
struct ifnet *tun_ifp; /* the interface */
struct sigio *tun_sigio; /* information for async I/O */
@@ -277,6 +271,7 @@
struct cdev *dev;
mtx_lock(&tp->tun_mtx);
+ tp->tun_flags |= TUN_DYING;
if ((tp->tun_flags & TUN_OPEN) != 0)
cv_wait_unlock(&tp->tun_cv, &tp->tun_mtx);
else
@@ -473,19 +468,13 @@
tp = dev->si_drv1;
}
- /*
- * XXXRW: This use of tun_pid is subject to error due to the
- * fact that a reference to the tunnel can live beyond the
- * death of the process that created it. Can we replace this
- * with a simple busy flag?
- */
mtx_lock(&tp->tun_mtx);
- if (tp->tun_pid != 0 && tp->tun_pid != td->td_proc->p_pid) {
+ if ((tp->tun_flags & (TUN_OPEN | TUN_DYING)) != 0) {
mtx_unlock(&tp->tun_mtx);
return (EBUSY);
}
- tp->tun_pid = td->td_proc->p_pid;
+ tp->tun_pid = td->td_proc->p_pid;
tp->tun_flags |= TUN_OPEN;
ifp = TUN2IFP(tp);
if_link_state_change(ifp, LINK_STATE_UP);
@@ -509,6 +498,16 @@
ifp = TUN2IFP(tp);
mtx_lock(&tp->tun_mtx);
+ /*
+ * Simply close the device if this isn't the controlling process. This
+ * may happen if, for instance, the tunnel has been handed off to
+ * another process. The original controller should be able to close it
+ * without putting us into an inconsistent state.
+ */
+ if (td->td_proc->p_pid != tp->tun_pid) {
+ mtx_unlock(&tp->tun_mtx);
+ return (0);
+ }
/*
* junk all pending output

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