[PATCH RFC 21/30] net: fec: quiesce packet processing before changing features
From: Russell King <hidden>
Date: 2014-06-20 12:13:30
Also in:
linux-arm-kernel
Subsystem:
freescale imx / mxc fec driver, networking drivers, the rest · Maintainers:
Wei Fang, Andrew Lunn, "David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Changing the features (receive checksumming) requires the hardware to be reprogrammed, and also changes the checks in the receive packet processing. The current implementation has a race - fec_set_features() changes the flags which alter the receive packet processing while the adapter is active, and potentially receiving frames. Only after we've modified the software flag do we shutdown and reconfigure the hardware. This can lead to packets being received and marked with a valid checksum (via CHECKSUM_UNNECESSARY) when the hardware checksum validation has not yet been enabled. We must quiesce the device, then change the software configuration for this feature, and then resume the device if it was previously running. The resulting code structure also allows us to add other configuration features in this path without having to quiesce and resume the network interface and device. Signed-off-by: Russell King <redacted> --- drivers/net/ethernet/freescale/fec_main.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-)
diff --git a/drivers/net/ethernet/freescale/fec_main.c b/drivers/net/ethernet/freescale/fec_main.c
index cc2fab7333fe..466268fffadd 100644
--- a/drivers/net/ethernet/freescale/fec_main.c
+++ b/drivers/net/ethernet/freescale/fec_main.c@@ -2347,12 +2347,21 @@ static void fec_poll_controller(struct net_device *dev) } #endif +#define FEATURES_NEED_QUIESCE NETIF_F_RXCSUM + static int fec_set_features(struct net_device *netdev, netdev_features_t features) { struct fec_enet_private *fep = netdev_priv(netdev); netdev_features_t changed = features ^ netdev->features; + /* Quiesce the device if necessary */ + if (netif_running(netdev) && changed & FEATURES_NEED_QUIESCE) { + napi_disable(&fep->napi); + netif_tx_lock_bh(netdev); + fec_stop(netdev); + } + netdev->features = features; /* Receive checksum has been changed */
@@ -2361,16 +2370,14 @@ static int fec_set_features(struct net_device *netdev, fep->csum_flags |= FLAG_RX_CSUM_ENABLED; else fep->csum_flags &= ~FLAG_RX_CSUM_ENABLED; + } - if (netif_running(netdev)) { - napi_disable(&fep->napi); - netif_tx_lock_bh(netdev); - fec_stop(netdev); - fec_restart(netdev, fep->phy_dev->duplex); - netif_wake_queue(netdev); - netif_tx_unlock_bh(netdev); - napi_enable(&fep->napi); - } + /* Resume the device after updates */ + if (netif_running(netdev) && changed & FEATURES_NEED_QUIESCE) { + fec_restart(netdev, fep->phy_dev->duplex); + netif_wake_queue(netdev); + netif_tx_unlock_bh(netdev); + napi_enable(&fep->napi); } return 0;
--
1.8.3.1