From mboxrd@z Thu Jan 1 00:00:00 1970 From: Eric Dumazet Subject: Re: [PATCH net-next-2.6 1/2] net: Get rid of rtnl_link_stats64 / net_device_stats union Date: Fri, 09 Jul 2010 06:25:43 +0200 Message-ID: <1278649543.2435.105.camel@edumazet-laptop> References: <1278631762.16013.307.camel@achroite.uk.solarflarecom.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: David Miller , netdev@vger.kernel.org, linux-net-drivers@solarflare.com To: Ben Hutchings Return-path: Received: from mail-ww0-f44.google.com ([74.125.82.44]:51351 "EHLO mail-ww0-f44.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750796Ab0GIEZv (ORCPT ); Fri, 9 Jul 2010 00:25:51 -0400 Received: by wwb24 with SMTP id 24so4476802wwb.1 for ; Thu, 08 Jul 2010 21:25:47 -0700 (PDT) In-Reply-To: <1278631762.16013.307.camel@achroite.uk.solarflarecom.com> Sender: netdev-owner@vger.kernel.org List-ID: Le vendredi 09 juillet 2010 =C3=A0 00:29 +0100, Ben Hutchings a =C3=A9c= rit : > In commit be1f3c2c027cc5ad735df6a45a542ed1db7ec48b "net: Enable 64-bi= t > net device statistics on 32-bit architectures" I redefined struct > net_device_stats so that it could be used in a union with struct > rtnl_link_stats64, avoiding the need for explicit copying or > conversion between the two. However, this is unsafe because there is > no locking required and no lock consistently held around calls to > dev_get_stats() and use of the statistics structure it returns. >=20 > In commit 28172739f0a276eb8d6ca917b3974c2edb036da3 "net: fix 64 bit > counters on 32 bit arches" Eric Dumazet dealt with that problem by > requiring callers of dev_get_stats() to provide storage for the > result. This means that the net_device::stats64 field and the paddin= g > in struct net_device_stats are now redundant, so remove them. >=20 > Update the comment on net_device_ops::ndo_get_stats64 to reflect its > new usage. >=20 > Change dev_txq_stats_fold() to use struct rtnl_link_stats64, since > that is what all its callers are really using and it is no longer > going to be compatible with struct net_device_stats. >=20 > Signed-off-by: Ben Hutchings > --- > drivers/net/macvlan.c | 2 +- > include/linux/netdevice.h | 70 ++++++++++++++++++-----------------= ---------- > net/8021q/vlan_dev.c | 2 +- > net/core/dev.c | 19 +++++++++--- > 4 files changed, 44 insertions(+), 49 deletions(-) >=20 > diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c > index 6112f14..1b28aae 100644 > --- a/drivers/net/macvlan.c > +++ b/drivers/net/macvlan.c > @@ -436,7 +436,7 @@ static struct rtnl_link_stats64 *macvlan_dev_get_= stats64(struct net_device *dev, > { > struct macvlan_dev *vlan =3D netdev_priv(dev); > =20 > - dev_txq_stats_fold(dev, (struct net_device_stats *)stats); > + dev_txq_stats_fold(dev, stats); > =20 > if (vlan->rx_stats) { > struct macvlan_rx_stats *p, accum =3D {0}; > diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h > index 8018f6b..17e95e3 100644 > --- a/include/linux/netdevice.h > +++ b/include/linux/netdevice.h > @@ -162,42 +162,32 @@ static inline bool dev_xmit_complete(int rc) > /* > * Old network device statistics. Fields are native words > * (unsigned long) so they can be read and written atomically. > - * Each field is padded to 64 bits for compatibility with > - * rtnl_link_stats64. > */ > =20 > -#if BITS_PER_LONG =3D=3D 64 > -#define NET_DEVICE_STATS_DEFINE(name) unsigned long name > -#elif defined(__LITTLE_ENDIAN) > -#define NET_DEVICE_STATS_DEFINE(name) unsigned long name, pad_ ## na= me > -#else > -#define NET_DEVICE_STATS_DEFINE(name) unsigned long pad_ ## name, na= me > -#endif > - > struct net_device_stats { > - NET_DEVICE_STATS_DEFINE(rx_packets); > - NET_DEVICE_STATS_DEFINE(tx_packets); > - NET_DEVICE_STATS_DEFINE(rx_bytes); > - NET_DEVICE_STATS_DEFINE(tx_bytes); > - NET_DEVICE_STATS_DEFINE(rx_errors); > - NET_DEVICE_STATS_DEFINE(tx_errors); > - NET_DEVICE_STATS_DEFINE(rx_dropped); > - NET_DEVICE_STATS_DEFINE(tx_dropped); > - NET_DEVICE_STATS_DEFINE(multicast); > - NET_DEVICE_STATS_DEFINE(collisions); > - NET_DEVICE_STATS_DEFINE(rx_length_errors); > - NET_DEVICE_STATS_DEFINE(rx_over_errors); > - NET_DEVICE_STATS_DEFINE(rx_crc_errors); > - NET_DEVICE_STATS_DEFINE(rx_frame_errors); > - NET_DEVICE_STATS_DEFINE(rx_fifo_errors); > - NET_DEVICE_STATS_DEFINE(rx_missed_errors); > - NET_DEVICE_STATS_DEFINE(tx_aborted_errors); > - NET_DEVICE_STATS_DEFINE(tx_carrier_errors); > - NET_DEVICE_STATS_DEFINE(tx_fifo_errors); > - NET_DEVICE_STATS_DEFINE(tx_heartbeat_errors); > - NET_DEVICE_STATS_DEFINE(tx_window_errors); > - NET_DEVICE_STATS_DEFINE(rx_compressed); > - NET_DEVICE_STATS_DEFINE(tx_compressed); > + unsigned long rx_packets; > + unsigned long tx_packets; > + unsigned long rx_bytes; > + unsigned long tx_bytes; > + unsigned long rx_errors; > + unsigned long tx_errors; > + unsigned long rx_dropped; > + unsigned long tx_dropped; > + unsigned long multicast; > + unsigned long collisions; > + unsigned long rx_length_errors; > + unsigned long rx_over_errors; > + unsigned long rx_crc_errors; > + unsigned long rx_frame_errors; > + unsigned long rx_fifo_errors; > + unsigned long rx_missed_errors; > + unsigned long tx_aborted_errors; > + unsigned long tx_carrier_errors; > + unsigned long tx_fifo_errors; > + unsigned long tx_heartbeat_errors; > + unsigned long tx_window_errors; > + unsigned long rx_compressed; > + unsigned long tx_compressed; > }; > =20 > #endif /* __KERNEL__ */ > @@ -666,14 +656,13 @@ struct netdev_rx_queue { > * Callback uses when the transmitter has not made any progress > * for dev->watchdog ticks. > * > - * struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *d= ev > + * struct rtnl_link_stats64* (*ndo_get_stats64)(struct net_device *d= ev, > * struct rtnl_link_stats64 *storage); > * struct net_device_stats* (*ndo_get_stats)(struct net_device *dev)= ; > * Called when a user wants to get the network device usage > * statistics. Drivers must do one of the following: > - * 1. Define @ndo_get_stats64 to update a rtnl_link_stats64 structur= e > - * (which should normally be dev->stats64) and return a ponter to > - * it. The structure must not be changed asynchronously. > + * 1. Define @ndo_get_stats64 to fill in a zero-initialised > + * rtnl_link_stats64 structure passed by the caller. > * 2. Define @ndo_get_stats to update a net_device_stats structure > * (which should normally be dev->stats) and return a pointer to > * it. The structure may be changed asynchronously only if each > @@ -888,10 +877,7 @@ struct net_device { > int ifindex; > int iflink; > =20 > - union { > - struct rtnl_link_stats64 stats64; > - struct net_device_stats stats; > - }; > + struct net_device_stats stats; > =20 > #ifdef CONFIG_WIRELESS_EXT > /* List of functions to handle Wireless Extensions (instead of ioct= l). > @@ -2147,7 +2133,7 @@ extern void dev_mcast_init(void); > extern const struct rtnl_link_stats64 *dev_get_stats(struct net_devi= ce *dev, > struct rtnl_link_stats64 *storage); > extern void dev_txq_stats_fold(const struct net_device *dev, > - struct net_device_stats *stats); > + struct rtnl_link_stats64 *stats); > =20 > extern int netdev_max_backlog; > extern int netdev_tstamp_prequeue; > diff --git a/net/8021q/vlan_dev.c b/net/8021q/vlan_dev.c > index 7865a4c..e66c9bf 100644 > --- a/net/8021q/vlan_dev.c > +++ b/net/8021q/vlan_dev.c > @@ -805,7 +805,7 @@ static u32 vlan_ethtool_get_flags(struct net_devi= ce *dev) > =20 > static struct rtnl_link_stats64 *vlan_dev_get_stats64(struct net_dev= ice *dev, struct rtnl_link_stats64 *stats) > { > - dev_txq_stats_fold(dev, (struct net_device_stats *)stats); > + dev_txq_stats_fold(dev, stats); > =20 > if (vlan_dev_info(dev)->vlan_rx_stats) { > struct vlan_rx_stats *p, accum =3D {0}; > diff --git a/net/core/dev.c b/net/core/dev.c > index eb4201c..5ec2eec 100644 > --- a/net/core/dev.c > +++ b/net/core/dev.c > @@ -5274,10 +5274,10 @@ void netdev_run_todo(void) > /** > * dev_txq_stats_fold - fold tx_queues stats > * @dev: device to get statistics from > - * @stats: struct net_device_stats to hold results > + * @stats: struct rtnl_link_stats64 to hold results > */ > void dev_txq_stats_fold(const struct net_device *dev, > - struct net_device_stats *stats) > + struct rtnl_link_stats64 *stats) > { > unsigned long tx_bytes =3D 0, tx_packets =3D 0, tx_dropped =3D 0; > unsigned int i; > @@ -5311,17 +5311,26 @@ const struct rtnl_link_stats64 *dev_get_stats= (struct net_device *dev, > struct rtnl_link_stats64 *storage) > { > const struct net_device_ops *ops =3D dev->netdev_ops; > + size_t i, n =3D sizeof(*storage) / sizeof(u64); > + u64 *stats64 =3D (u64 *)storage; > + const unsigned long *stats; > =20 > if (ops->ndo_get_stats64) { > memset(storage, 0, sizeof(*storage)); > return ops->ndo_get_stats64(dev, storage); > } > + > if (ops->ndo_get_stats) { > - memcpy(storage, ops->ndo_get_stats(dev), sizeof(*storage)); > + stats =3D (const unsigned long *)ops->ndo_get_stats(dev); > + for (i =3D 0; i < n; i++) > + stats64[i] =3D stats[i]; This could be a small helper function, to hide the sizeof(*storage) / sizeof(u64) magic.. static void stats_to_stats64(struct rtnl_link_stats64 *dst, const net_device_stats *src) { #if BITS_PER_LONG =3D=3D 64 BUILD_BUG_ON(sizeof(*dst) !=3D sizeof(*src)); memcpy(dst, src, sizeof(*src)); #else size_t i, n =3D sizeof(*dst) / sizeof(u64); u64 *stats64 =3D (u64 *)dst; const unsigned long *stats =3D (const unsigned long *)src; BUILD_BUG_ON(sizeof(*src) !=3D n * sizeof(unsigned long)); for (i =3D 0; i < n, i++) stats64[i] =3D stats[i]; #endif } =20 Thanks !