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Add a dying flag to prevent races at detach.

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I tried re-ordering ether_ifdetach(), but this created a new race
where sometimes, when under heavy receive load (>1Mpps) and running
tcpdump, the machine would panic.  At panic, the ithread was still in
the original (not dead) if_input() path, and was accessing stale BPF
data structs.  By using a dying flag, I can close the interface prior
to if_detach() to be certain the interface cannot send packets up in
the middle of ether_ifdetach.
This commit is contained in:
Andrew Gallatin 2009-06-24 21:09:56 +00:00
parent aeb56f0662
commit 8c5d766cd7
2 changed files with 7 additions and 0 deletions
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6
sys/dev/mxge/if_mxge.c
View File

@ -3906,6 +3906,10 @@ mxge_ioctl(struct ifnet *ifp, u_long command, caddr_t data)
case SIOCSIFFLAGS:
mtx_lock(&sc->driver_mtx);
if (sc->dying) {
mtx_unlock(&sc->driver_mtx);
return EINVAL;
}
if (ifp->if_flags & IFF_UP) {
if (!(ifp->if_drv_flags & IFF_DRV_RUNNING)) {
err = mxge_open(sc);
@ -4590,6 +4594,7 @@ mxge_attach(device_t dev)
mxge_media_status);
mxge_set_media(sc, IFM_ETHER | IFM_AUTO);
mxge_media_probe(sc);
sc->dying = 0;
ether_ifattach(ifp, sc->mac_addr);
/* ether_ifattach sets mtu to ETHERMTU */
if (mxge_initial_mtu != ETHERMTU)
@ -4637,6 +4642,7 @@ mxge_detach(device_t dev)
return EBUSY;
}
mtx_lock(&sc->driver_mtx);
sc->dying = 1;
if (sc->ifp->if_drv_flags & IFF_DRV_RUNNING)
mxge_close(sc);
mtx_unlock(&sc->driver_mtx);

1
sys/dev/mxge/if_mxge_var.h
View File

@ -266,6 +266,7 @@ struct mxge_softc {
int need_media_probe;
int num_slices;
int rx_ring_size;
int dying;
mxge_dma_t dmabench_dma;
struct callout co_hdl;
struct sysctl_oid *slice_sysctl_tree;