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diff --git a/sys/net/if.c b/sys/net/if.c
index 0aa1cbbb7b41..b3ab75144460 100644
--- a/sys/net/if.c
+++ b/sys/net/if.c
@@ -459,6 +459,7 @@ if_unlink_ifnet(struct ifnet *ifp, bool vmove)
struct ifnet *iter;
int found = 0;
+ sx_assert(&ifnet_detach_sxlock, SX_XLOCKED);
IFNET_WLOCK();
CK_STAILQ_FOREACH(iter, &V_ifnet, if_link)
if (iter == ifp) {
@@ -1087,14 +1088,23 @@ if_detach(struct ifnet *ifp)
{
bool found;
+ /*
+ * The driver private data holds a strong reference to the ifnet, and
+ * it is actually the "owner", hence this routine shall never fail.
+ *
+ * Ideally we can loop retrying when we lose race with other threads
+ * those run if_unlink_ifnet(). For simplicity, use ifnet_detach_sxlock
+ * to serialize all the detach / vmove operations.
+ */
+ sx_xlock(&ifnet_detach_sxlock);
CURVNET_SET_QUIET(ifp->if_vnet);
found = if_unlink_ifnet(ifp, false);
- if (found) {
- sx_xlock(&ifnet_detach_sxlock);
- if_detach_internal(ifp, false);
- sx_xunlock(&ifnet_detach_sxlock);
- }
+ if (! found)
+ panic("%s: interface is not on the active list",
+ ifp->if_xname);
+ if_detach_internal(ifp, false);
CURVNET_RESTORE();
+ sx_xunlock(&ifnet_detach_sxlock);
}
/*
@@ -1403,13 +1413,14 @@ if_vmove_reclaim(struct thread *td, char *ifname, int jid)
}
/* Get interface back from child jail/vnet. */
+ sx_xlock(&ifnet_detach_sxlock);
found = if_unlink_ifnet(ifp, true);
if (! found) {
+ sx_xunlock(&ifnet_detach_sxlock);
CURVNET_RESTORE();
prison_free(pr);
return (ENODEV);
}
- sx_xlock(&ifnet_detach_sxlock);
if_vmove(ifp, vnet_dst);
sx_xunlock(&ifnet_detach_sxlock);
CURVNET_RESTORE();
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