| Message ID | 1345497411.2659.28.camel@bwh-desktop.uk.solarflarecom.com |
|---|---|
| State | Accepted, archived |
| Delegated to: | David Miller |
| Headers | show |
From: Ben Hutchings <bhutchings@solarflare.com> Date: Mon, 20 Aug 2012 22:16:51 +0100 > This initialises the operstate synchronously at registration time > only. Ok, this looks good to me, applied. Thanks Ben. > This seems to deal properly with the registration-time problem, but not > the case where a device is brought down and then up again. Many but not > all drivers that support carrier detection call netif_carrier_off() in > their ndo_stop method. Should the others be changed, or is there some > way we can make that automatic? There are several cases. For example, if the device does not power down the PHY over stop/start it should leave the carrier state alone. This is the case for every NIC that runs management firmware, which therefore needs the link to stay up even when the NIC is administratively brought down. If it does power down the PHY, that netif_carrier_off() call should already be contained in the PHY powerdown code. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Fri, 2012-08-24 at 12:48 -0400, David Miller wrote: > From: Ben Hutchings <bhutchings@solarflare.com> > Date: Mon, 20 Aug 2012 22:16:51 +0100 > > > This initialises the operstate synchronously at registration time > > only. > > Ok, this looks good to me, applied. Thanks Ben. > > > This seems to deal properly with the registration-time problem, but not > > the case where a device is brought down and then up again. Many but not > > all drivers that support carrier detection call netif_carrier_off() in > > their ndo_stop method. Should the others be changed, or is there some > > way we can make that automatic? > > There are several cases. > > For example, if the device does not power down the PHY over stop/start > it should leave the carrier state alone. This is the case for every > NIC that runs management firmware, which therefore needs the link to > stay up even when the NIC is administratively brought down. > > If it does power down the PHY, that netif_carrier_off() call should > already be contained in the PHY powerdown code. Right, that makes sense to me. Ben.
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 1d6ab69..72ae4cf 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -2224,6 +2224,7 @@ 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 ce1bccb..2baeceb 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -5639,6 +5639,8 @@ 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 c3519c6..a019222 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))
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 <bhutchings@solarflare.com> --- This seems to deal properly with the registration-time problem, but not the case where a device is brought down and then up again. Many but not all drivers that support carrier detection call netif_carrier_off() in their ndo_stop method. Should the others be changed, or is there some way we can make that automatic? Ben. include/linux/netdevice.h | 1 + net/core/dev.c | 2 ++ net/core/link_watch.c | 8 ++++++++ 3 files changed, 11 insertions(+), 0 deletions(-)