From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DB4841A735 for ; Mon, 9 Oct 2023 13:51:30 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="phW/JCKN" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 51F67C433C8; Mon, 9 Oct 2023 13:51:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1696859490; bh=WmZcyGVuMhtcvPCZ3d81wXTbu0w6t4cpMSSuzxbJnTI=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=phW/JCKNY86erMLYEcp7GfbsJ0X7bqx86/ZwqJUTplxgYNCtJVxDGSBdQcmp8XRE7 +wgOge5Q5xqbsKI6/uk9zBj8eI/l2+DNAMeD5AZLuSLMh65ORU2SYrUXMr8wtRtGE4 3NAUbvkpQtmJhKffOLc7c2nRXTPnPCkWLG36l904= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Eric Dumazet , "David S. Miller" , Sasha Levin Subject: [PATCH 4.19 10/91] net: add atomic_long_t to net_device_stats fields Date: Mon, 9 Oct 2023 15:05:42 +0200 Message-ID: <20231009130111.890670188@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20231009130111.518916887@linuxfoundation.org> References: <20231009130111.518916887@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ From: Eric Dumazet [ Upstream commit 6c1c5097781f563b70a81683ea6fdac21637573b ] Long standing KCSAN issues are caused by data-race around some dev->stats changes. Most performance critical paths already use per-cpu variables, or per-queue ones. It is reasonable (and more correct) to use atomic operations for the slow paths. This patch adds an union for each field of net_device_stats, so that we can convert paths that are not yet protected by a spinlock or a mutex. netdev_stats_to_stats64() no longer has an #if BITS_PER_LONG==64 Note that the memcpy() we were using on 64bit arches had no provision to avoid load-tearing, while atomic_long_read() is providing the needed protection at no cost. Signed-off-by: Eric Dumazet Signed-off-by: David S. Miller Stable-dep-of: 44bdb313da57 ("net: bridge: use DEV_STATS_INC()") Signed-off-by: Sasha Levin --- include/linux/netdevice.h | 58 +++++++++++++++++++++++---------------- include/net/dst.h | 5 ++-- net/core/dev.c | 14 ++-------- 3 files changed, 40 insertions(+), 37 deletions(-) diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h index 7e9df3854420a..e977118111f61 100644 --- a/include/linux/netdevice.h +++ b/include/linux/netdevice.h @@ -162,31 +162,38 @@ static inline bool dev_xmit_complete(int rc) * (unsigned long) so they can be read and written atomically. */ +#define NET_DEV_STAT(FIELD) \ + union { \ + unsigned long FIELD; \ + atomic_long_t __##FIELD; \ + } + struct net_device_stats { - 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; + NET_DEV_STAT(rx_packets); + NET_DEV_STAT(tx_packets); + NET_DEV_STAT(rx_bytes); + NET_DEV_STAT(tx_bytes); + NET_DEV_STAT(rx_errors); + NET_DEV_STAT(tx_errors); + NET_DEV_STAT(rx_dropped); + NET_DEV_STAT(tx_dropped); + NET_DEV_STAT(multicast); + NET_DEV_STAT(collisions); + NET_DEV_STAT(rx_length_errors); + NET_DEV_STAT(rx_over_errors); + NET_DEV_STAT(rx_crc_errors); + NET_DEV_STAT(rx_frame_errors); + NET_DEV_STAT(rx_fifo_errors); + NET_DEV_STAT(rx_missed_errors); + NET_DEV_STAT(tx_aborted_errors); + NET_DEV_STAT(tx_carrier_errors); + NET_DEV_STAT(tx_fifo_errors); + NET_DEV_STAT(tx_heartbeat_errors); + NET_DEV_STAT(tx_window_errors); + NET_DEV_STAT(rx_compressed); + NET_DEV_STAT(tx_compressed); }; +#undef NET_DEV_STAT #include @@ -4842,4 +4849,9 @@ do { \ #define PTYPE_HASH_SIZE (16) #define PTYPE_HASH_MASK (PTYPE_HASH_SIZE - 1) +/* Note: Avoid these macros in fast path, prefer per-cpu or per-queue counters. */ +#define DEV_STATS_INC(DEV, FIELD) atomic_long_inc(&(DEV)->stats.__##FIELD) +#define DEV_STATS_ADD(DEV, FIELD, VAL) \ + atomic_long_add((VAL), &(DEV)->stats.__##FIELD) + #endif /* _LINUX_NETDEVICE_H */ diff --git a/include/net/dst.h b/include/net/dst.h index 50258a8131377..97267997601f5 100644 --- a/include/net/dst.h +++ b/include/net/dst.h @@ -362,9 +362,8 @@ static inline void __skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, static inline void skb_tunnel_rx(struct sk_buff *skb, struct net_device *dev, struct net *net) { - /* TODO : stats should be SMP safe */ - dev->stats.rx_packets++; - dev->stats.rx_bytes += skb->len; + DEV_STATS_INC(dev, rx_packets); + DEV_STATS_ADD(dev, rx_bytes, skb->len); __skb_tunnel_rx(skb, dev, net); } diff --git a/net/core/dev.c b/net/core/dev.c index a9c8660a2570f..3bf40c288c032 100644 --- a/net/core/dev.c +++ b/net/core/dev.c @@ -9035,24 +9035,16 @@ void netdev_run_todo(void) void netdev_stats_to_stats64(struct rtnl_link_stats64 *stats64, const struct net_device_stats *netdev_stats) { -#if BITS_PER_LONG == 64 - BUILD_BUG_ON(sizeof(*stats64) < sizeof(*netdev_stats)); - memcpy(stats64, netdev_stats, sizeof(*netdev_stats)); - /* zero out counters that only exist in rtnl_link_stats64 */ - memset((char *)stats64 + sizeof(*netdev_stats), 0, - sizeof(*stats64) - sizeof(*netdev_stats)); -#else - size_t i, n = sizeof(*netdev_stats) / sizeof(unsigned long); - const unsigned long *src = (const unsigned long *)netdev_stats; + size_t i, n = sizeof(*netdev_stats) / sizeof(atomic_long_t); + const atomic_long_t *src = (atomic_long_t *)netdev_stats; u64 *dst = (u64 *)stats64; BUILD_BUG_ON(n > sizeof(*stats64) / sizeof(u64)); for (i = 0; i < n; i++) - dst[i] = src[i]; + dst[i] = atomic_long_read(&src[i]); /* zero out counters that only exist in rtnl_link_stats64 */ memset((char *)stats64 + n * sizeof(u64), 0, sizeof(*stats64) - n * sizeof(u64)); -#endif } EXPORT_SYMBOL(netdev_stats_to_stats64); -- 2.40.1