Author: royger
Date: Tue Jun 26 14:07:11 2018
New Revision: 335664
URL: https://svnweb.freebsd.org/changeset/base/335664
Log:
xen-netback: fix LOR
lock order reversal: (sleepable after non-sleepable)
1st 0xfffffe00357ff538 xnb_softc (xen netback softc lock) @
/usr/src/sys/dev/xen/netback/netback.c:1069
2nd 0xffffffff81fdccb0 intrsrc (intrsrc) @
/usr/src/sys/x86/x86/intr_machdep.c:224
There's no need to hold the lock since the cleaning of the interrupt
cannot happen in parallel due to the XNBF_IN_SHUTDOWN flag being set.
Note that the locking in netback needs some improvement or
clarification.
While there also remove a double newline.
Sponsored by: Citrix Systems R&D
Modified:
head/sys/dev/xen/netback/netback.c
Modified: head/sys/dev/xen/netback/netback.c
==============================================================================
--- head/sys/dev/xen/netback/netback.c Tue Jun 26 14:01:03 2018
(r335663)
+++ head/sys/dev/xen/netback/netback.c Tue Jun 26 14:07:11 2018
(r335664)
@@ -662,6 +662,7 @@ xnb_disconnect(struct xnb_softc *xnb)
mtx_lock(&xnb->rx_lock);
mtx_unlock(&xnb->rx_lock);
+ mtx_lock(&xnb->sc_lock);
/* Free malloc'd softc member variables */
if (xnb->bridge != NULL) {
free(xnb->bridge, M_XENSTORE);
@@ -689,6 +690,8 @@ xnb_disconnect(struct xnb_softc *xnb)
sizeof(struct xnb_ring_config));
xnb->flags &= ~XNBF_RING_CONNECTED;
+ mtx_unlock(&xnb->sc_lock);
+
return (0);
}
@@ -1066,17 +1069,14 @@ xnb_shutdown(struct xnb_softc *xnb)
if_free(xnb->xnb_ifp);
xnb->xnb_ifp = NULL;
}
- mtx_lock(&xnb->sc_lock);
xnb_disconnect(xnb);
- mtx_unlock(&xnb->sc_lock);
if (xenbus_get_state(xnb->dev) < XenbusStateClosing)
xenbus_set_state(xnb->dev, XenbusStateClosing);
mtx_lock(&xnb->sc_lock);
xnb->flags &= ~XNBF_IN_SHUTDOWN;
-
/* Indicate to xnb_detach() that is it safe to proceed. */
wakeup(xnb);
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