From 35876b5ffc154c357476b2c3bdab10feaf4bd8f0 Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Thu, 14 Feb 2013 03:18:57 +0000 Subject: 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 Signed-off-by: Jan Beulich Signed-off-by: David Vrabel Reported-by: Christopher S. Aker Acked-by: Ian Campbell Signed-off-by: David S. Miller --- drivers/net/xen-netback/netback.c | 8 ++++---- 1 file changed, 4 insertions(+), 4 deletions(-) (limited to 'drivers/net/xen-netback') diff --git a/drivers/net/xen-netback/netback.c b/drivers/net/xen-netback/netback.c index 2b9520c46e97..cd49ba949636 100644 --- a/drivers/net/xen-netback/netback.c +++ b/drivers/net/xen-netback/netback.c @@ -911,13 +911,13 @@ static int netbk_count_requests(struct xenvif *vif, 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 @@ static int netbk_count_requests(struct xenvif *vif, 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 @@ static int netbk_count_requests(struct xenvif *vif, 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; -- cgit v1.2.3 From 3e55f8b306cf305832a4ac78aa82e1b40e818ece Mon Sep 17 00:00:00 2001 From: David Vrabel Date: Thu, 14 Feb 2013 03:18:58 +0000 Subject: xen-netback: cancel the credit timer when taking the vif down If the credit timer is left armed after calling xen_netbk_remove_xenvif(), then it may fire and attempt to schedule the vif which will then oops as vif->netbk == NULL. This may happen both in the fatal error path and during normal disconnection from the front end. The sequencing during shutdown is critical to ensure that: a) vif->netbk doesn't become unexpectedly NULL; and b) the net device/vif is not freed. 1. Mark as unschedulable (netif_carrier_off()). 2. Synchronously cancel the timer. 3. Remove the vif from the schedule list. 4. Remove it from it netback thread group. 5. Wait for vif->refcnt to become 0. Signed-off-by: David Vrabel Acked-by: Ian Campbell Reported-by: Christopher S. Aker Signed-off-by: David S. Miller --- drivers/net/xen-netback/interface.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) (limited to 'drivers/net/xen-netback') diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index b8c5193bd420..221f4265f7d6 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -132,6 +132,7 @@ static void xenvif_up(struct xenvif *vif) static void xenvif_down(struct xenvif *vif) { disable_irq(vif->irq); + del_timer_sync(&vif->credit_timeout); xen_netbk_deschedule_xenvif(vif); xen_netbk_remove_xenvif(vif); } @@ -363,8 +364,6 @@ void xenvif_disconnect(struct xenvif *vif) atomic_dec(&vif->refcnt); wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0); - del_timer_sync(&vif->credit_timeout); - if (vif->irq) unbind_from_irqhandler(vif->irq, vif); -- cgit v1.2.3