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sfc: Detach net device when stopping queues for reconfiguration

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We must only ever stop TX queues when they are full or the net device
is not 'ready' so far as the net core, and specifically the watchdog,
is concerned.  Otherwise, the watchdog may fire *immediately* if no
packets have been added to the queue in the last 5 seconds.

The device is ready if all the following are true:

(a) It has a qdisc
(b) It is marked present
(c) It is running
(d) The link is reported up

(a) and (c) are normally true, and must not be changed by a driver.
(d) is under our control, but fake link changes may disturb userland.
This leaves (b).  We already mark the device absent during reset
and self-test, but we need to do the same during MTU changes and ring
reallocation.  We don't need to do this when the device is brought
down because then (c) is already false.

Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
This commit is contained in:
Ben Hutchings 2013-01-28 19:01:06 +00:00
parent b590ace09d
commit 29c69a4882
1 changed files with 12 additions and 4 deletions
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16
drivers/net/ethernet/sfc/efx.c
View File

@ -779,6 +779,7 @@ efx_realloc_channels(struct efx_nic *efx, u32 rxq_entries, u32 txq_entries)
tx_queue->txd.entries);
}
efx_device_detach_sync(efx);
efx_stop_all(efx);
efx_stop_interrupts(efx, true);
@ -832,6 +833,7 @@ out:
efx_start_interrupts(efx, true);
efx_start_all(efx);
netif_device_attach(efx->net_dev);
return rc;
rollback:
@ -1641,8 +1643,12 @@ static void efx_stop_all(struct efx_nic *efx)
/* Flush efx_mac_work(), refill_workqueue, monitor_work */
efx_flush_all(efx);
/* Stop the kernel transmit interface late, so the watchdog
* timer isn't ticking over the flush */
/* Stop the kernel transmit interface. This is only valid if
* the device is stopped or detached; otherwise the watchdog
* may fire immediately.
*/
WARN_ON(netif_running(efx->net_dev) &&
netif_device_present(efx->net_dev));
netif_tx_disable(efx->net_dev);
efx_stop_datapath(efx);
@ -1963,16 +1969,18 @@ static int efx_change_mtu(struct net_device *net_dev, int new_mtu)
if (new_mtu > EFX_MAX_MTU)
return -EINVAL;
efx_stop_all(efx);
netif_dbg(efx, drv, efx->net_dev, "changing MTU to %d\n", new_mtu);
efx_device_detach_sync(efx);
efx_stop_all(efx);
mutex_lock(&efx->mac_lock);
net_dev->mtu = new_mtu;
efx->type->reconfigure_mac(efx);
mutex_unlock(&efx->mac_lock);
efx_start_all(efx);
netif_device_attach(efx->net_dev);
return 0;
}