netdev - [PATCH 3/8] netback: get/put module along with vif connect/disconnect

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Fri, 15 Feb 2013 16:00:04 +0000
From:	Wei Liu <wei.liu2@...rix.com>
To:	<xen-devel@...ts.xen.org>, <netdev@...r.kernel.org>,
	<ian.campbell@...rix.com>, <konrad.wilk@...cle.com>,
	<annie.li@...cle.com>
CC:	Wei Liu <wei.liu2@...rix.com>
Subject: [PATCH 3/8] netback: get/put module along with vif connect/disconnect

If there is vif running and user unloads netback, guest's network interface
just mysteriously stops working. So we need to prevent unloading netback
module if there is vif running.

The disconnect function of vif may get called by the generic framework even
before vif connects, so thers is an extra check on whether we actually need to
put module when disconnecting a vif.

Signed-off-by: Wei Liu <wei.liu2@...rix.com>
---
 drivers/net/xen-netback/interface.c |   18 +++++++++++++++++-
 1 file changed, 17 insertions(+), 1 deletion(-)

diff --git a/drivers/net/xen-netback/interface.c b/drivers/net/xen-netback/interface.c
index 221f426..db638e1 100644
--- a/drivers/net/xen-netback/interface.c
+++ b/drivers/net/xen-netback/interface.c
@@ -314,6 +314,8 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
 	if (vif->irq)
 		return 0;
 
+	__module_get(THIS_MODULE);
+
 	err = xen_netbk_map_frontend_rings(vif, tx_ring_ref, rx_ring_ref);
 	if (err < 0)
 		goto err;
@@ -341,6 +343,7 @@ int xenvif_connect(struct xenvif *vif, unsigned long tx_ring_ref,
 err_unmap:
 	xen_netbk_unmap_frontend_rings(vif);
 err:
+	module_put(THIS_MODULE);
 	return err;
 }
 
@@ -358,18 +361,31 @@ void xenvif_carrier_off(struct xenvif *vif)
 
 void xenvif_disconnect(struct xenvif *vif)
 {
+	/*
+	 * This function may get called even before vif connets, set
+	 * need_module_put if vif->irq != 0, which means vif has
+	 * already connected, we should call module_put to balance the
+	 * previous __module_get.
+	 */
+	int need_module_put = 0;
+
 	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->irq)
+	if (vif->irq) {
 		unbind_from_irqhandler(vif->irq, vif);
+		need_module_put = 1;
+	}
 
 	unregister_netdev(vif->dev);
 
 	xen_netbk_unmap_frontend_rings(vif);
 
 	free_netdev(vif->dev);
+
+	if (need_module_put)
+		module_put(THIS_MODULE);
 }
-- 
1.7.10.4

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html