From 8f4cccbbd92f2ad0ddbbc498ef7cee2a1c3defe9 Mon Sep 17 00:00:00 2001 From: Ben Hutchings Date: Mon, 20 Aug 2012 22:16:51 +0100 Subject: [PATCH] net: Set device operstate at registration time The operstate of a device is initially IF_OPER_UNKNOWN and is updated asynchronously by linkwatch after each change of carrier state reported by the driver. The default carrier state of a net device is on, and this will never be changed on drivers that do not support carrier detection, thus the operstate remains IF_OPER_UNKNOWN. For devices that do support carrier detection, the driver must set the carrier state to off initially, then poll the hardware state when the device is opened. However, we must not activate linkwatch for a unregistered device, and commit b473001 ('net: Do not fire linkwatch events until the device is registered.') ensured that we don't. But this means that the operstate for many devices that support carrier detection remains IF_OPER_UNKNOWN when it should be IF_OPER_DOWN. The same issue exists with the dormant state. The proper initialisation sequence, avoiding a race with opening of the device, is: rtnl_lock(); rc = register_netdevice(dev); if (rc) goto out_unlock; netif_carrier_off(dev); /* or netif_dormant_on(dev) */ rtnl_unlock(); but it seems silly that this should have to be repeated in so many drivers. Further, the operstate seen immediately after opening the device may still be IF_OPER_UNKNOWN due to the asynchronous nature of linkwatch. Commit 22604c8 ('net: Fix for initial link state in 2.6.28') attempted to fix this by setting the operstate synchronously, but it was reverted as it could lead to deadlock. This initialises the operstate synchronously at registration time only. Signed-off-by: Ben Hutchings Signed-off-by: David S. Miller --- include/linux/netdevice.h | 1 + net/core/dev.c | 2 ++ net/core/link_watch.c | 8 ++++++++ 3 files changed, 11 insertions(+) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 9ad7fa8c10e0..ccac82e61604 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2227,6 +2227,7 @@ static inline void dev_hold(struct net_device *dev) * kind of lower layer not just hardware media. */ +extern void linkwatch_init_dev(struct net_device *dev); extern void linkwatch_fire_event(struct net_device *dev); extern void linkwatch_forget_dev(struct net_device *dev); diff --git a/net/core/dev.c b/net/core/dev.c index bc857fead8c8..2f25d0cac51c 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5648,6 +5648,8 @@ int register_netdevice(struct net_device *dev) set_bit(__LINK_STATE_PRESENT, &dev->state); + linkwatch_init_dev(dev); + dev_init_scheduler(dev); dev_hold(dev); list_netdevice(dev); diff --git a/net/core/link_watch.c b/net/core/link_watch.c index c3519c6d1b16..a01922219a23 100644 --- a/net/core/link_watch.c +++ b/net/core/link_watch.c @@ -76,6 +76,14 @@ static void rfc2863_policy(struct net_device *dev) } +void linkwatch_init_dev(struct net_device *dev) +{ + /* Handle pre-registration link state changes */ + if (!netif_carrier_ok(dev) || netif_dormant(dev)) + rfc2863_policy(dev); +} + + static bool linkwatch_urgent_event(struct net_device *dev) { if (!netif_running(dev))