xen-netback: correctly return errors from netbk_count_requests()
netbk_count_requests() could detect an error, call
netbk_fatal_tx_error() but return 0. The vif may then be used
afterwards (e.g., in a call to netbk_tx_error().
Since netbk_fatal_tx_error() could set vif->refcnt to 1, the vif may
be freed immediately after the call to netbk_fatal_tx_error() (e.g.,
if the vif is also removed).
Netback thread Xenwatch thread
-------------------------------------------
netbk_fatal_tx_err() netback_remove()
xenvif_disconnect()
...
free_netdev()
netbk_tx_err() Oops!
Signed-off-by: Wei Liu <[email protected]>
Signed-off-by: Jan Beulich <[email protected]>
Signed-off-by: David Vrabel <[email protected]>
Reported-by: Christopher S. Aker <[email protected]>
Acked-by: Ian Campbell <[email protected]>
Signed-off-by: David S. Miller <[email protected]>
diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c
index 2b9520c..cd49ba9 100644
--- a/drivers/net/xen-netback/netback.c
+++ b/drivers/net/xen-netback/netback.c
@@ -911,13 +911,13 @@
if (frags >= work_to_do) {
netdev_err(vif->dev, "Need more frags\n");
netbk_fatal_tx_err(vif);
- return -frags;
+ return -ENODATA;
}
if (unlikely(frags >= MAX_SKB_FRAGS)) {
netdev_err(vif->dev, "Too many frags\n");
netbk_fatal_tx_err(vif);
- return -frags;
+ return -E2BIG;
}
memcpy(txp, RING_GET_REQUEST(&vif->tx, cons + frags),
@@ -925,7 +925,7 @@
if (txp->size > first->size) {
netdev_err(vif->dev, "Frag is bigger than frame.\n");
netbk_fatal_tx_err(vif);
- return -frags;
+ return -EIO;
}
first->size -= txp->size;
@@ -935,7 +935,7 @@
netdev_err(vif->dev, "txp->offset: %x, size: %u\n",
txp->offset, txp->size);
netbk_fatal_tx_err(vif);
- return -frags;
+ return -EINVAL;
}
} while ((txp++)->flags & XEN_NETTXF_more_data);
return frags;
