From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wei Liu Subject: [[PATCH stable <3.12]] xen-netback: fix refcnt unbalance for 3.11 and earlier versions Date: Thu, 28 Nov 2013 12:48:09 +0000 Message-ID: <1385642889-11513-1-git-send-email-wei.liu2@citrix.com> Mime-Version: 1.0 Content-Type: text/plain Cc: , Wei Liu , Ian Campbell , Konrad Wilk , David Vrabel To: , , Return-path: Sender: stable-owner@vger.kernel.org List-Id: netdev.vger.kernel.org With the introduction of "xen-netback: Don't destroy the netdev until the vif is shut down" (upstream commit id 279f438e36), vif disconnect and free are separated. However in the backported verion reference counting code was not correctly modified, and the reset of vif->tx_irq was lost. If frontend goes through vif life cycle more than once the reference counting is skewed. This patch adds back the missing tx_irq reset line. It also moves several lines of the reference counting code to vif_free, so the moved code corresponds to the counterpart in vif_alloc, thus the reference counting is balanced. 3.12 and onward versions are not affected by this bug, because reference counting code was removed due to the introduction of 1:1 model. This pacth should be backported to all stable verions which are lower than 3.12 and have 279f438e36. Reported-and-tested-by: Tomasz Wroblewski Signed-off-by: Wei Liu Cc: Ian Campbell Cc: Konrad Wilk Cc: David Vrabel --- drivers/net/xen-netback/interface.c | 7 ++++--- 1 file changed, 4 insertions(+), 3 deletions(-) diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c index d28324a..342d4e5 100644 --- a/drivers/net/xen-netback/interface.c +++ b/drivers/net/xen-netback/interface.c @@ -418,9 +418,6 @@ void xenvif_disconnect(struct xenvif *vif) if (netif_carrier_ok(vif->dev)) xenvif_carrier_off(vif); - atomic_dec(&vif->refcnt); - wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0); - if (vif->tx_irq) { if (vif->tx_irq == vif->rx_irq) unbind_from_irqhandler(vif->tx_irq, vif); @@ -428,6 +425,7 @@ void xenvif_disconnect(struct xenvif *vif) unbind_from_irqhandler(vif->tx_irq, vif); unbind_from_irqhandler(vif->rx_irq, vif); } + vif->tx_irq = 0; } xen_netbk_unmap_frontend_rings(vif); @@ -435,6 +433,9 @@ void xenvif_disconnect(struct xenvif *vif) void xenvif_free(struct xenvif *vif) { + atomic_dec(&vif->refcnt); + wait_event(vif->waiting_to_free, atomic_read(&vif->refcnt) == 0); + unregister_netdev(vif->dev); free_netdev(vif->dev); -- 1.7.10.4