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lagg: wrap lagg_port2req() into LAGG_SLOCK()

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Although a port addition is coded in a sequence where first all softc
information is fulfilled and only then it is attached to the lagg, we
still need a locking primitive to guarantee cache invalidation.  Panic
observed in the wild shows that lacp_portreq() called via
lagg_port_ioctl(SIOCGLAGGPORT) immediately after port creation may see
lp->lp_psc as NULL and panic.  In the core file we will see valid data
all around.  A race via lagg_ioctl() wasn't observed but potentially
is possible.

Differential Revision:	https://reviews.freebsd.org/D43501
This commit is contained in:
Gleb Smirnoff 2024-02-23 17:56:46 -08:00
parent 4c6ceca9cc
commit 48698ead6f
1 changed files with 7 additions and 1 deletions
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8
sys/net/if_lagg.c
View file

@ -83,8 +83,10 @@ MODULE_DEPEND(if_lagg, netmap, 1, 1, 1);
#define LAGG_SX_DESTROY(_sc) sx_destroy(&(_sc)->sc_sx)
#define LAGG_XLOCK(_sc) sx_xlock(&(_sc)->sc_sx)
#define LAGG_XUNLOCK(_sc) sx_xunlock(&(_sc)->sc_sx)
#define LAGG_SXLOCK_ASSERT(_sc) sx_assert(&(_sc)->sc_sx, SA_LOCKED)
#define LAGG_XLOCK_ASSERT(_sc) sx_assert(&(_sc)->sc_sx, SA_XLOCKED)
#define LAGG_SLOCK(_sc) sx_slock(&(_sc)->sc_sx)
#define LAGG_SUNLOCK(_sc) sx_sunlock(&(_sc)->sc_sx)
#define LAGG_SXLOCK_ASSERT(_sc) sx_assert(&(_sc)->sc_sx, SA_LOCKED)
/* Special flags we should propagate to the lagg ports. */
static struct {
@ -1044,7 +1046,9 @@ lagg_port_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
break;
}
LAGG_SLOCK(sc);
lagg_port2req(lp, rp);
LAGG_SUNLOCK(sc);
NET_EPOCH_EXIT(et);
break;
@ -1581,7 +1585,9 @@ lagg_ioctl(struct ifnet *ifp, u_long cmd, caddr_t data)
break;
}
LAGG_SLOCK(sc);
lagg_port2req(lp, rp);
LAGG_SUNLOCK(sc);
NET_EPOCH_EXIT(et);
if_rele(tpif);
break;