[PATCH 4.19 021/131] net: place xmit recursion in softnet data

Sasha Levin
2020-06-29T20:07:34Z

From: Florian Westphal <fw@strlen.de>

commit 97cdcf37b57e3f204be3000b9eab9686f38b4356 upstream.

This fills a hole in softnet data, so no change in structure size.

Also prepares for xmit_more placement in the same spot;
skb->xmit_more will be removed in followup patch.

Signed-off-by: Florian Westphal <fw@strlen.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
include/linux/netdevice.h | 40 +++++++++++++++++++++++++++++++--------
net/core/dev.c | 10 +++-------
net/core/filter.c | 6 +++---
3 files changed, 38 insertions(+), 18 deletions(-)

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 84bbdcbb199a9..41beebcc61f45 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -2620,14 +2620,6 @@ void netdev_freemem(struct net_device *dev);
void synchronize_net(void);
int init_dummy_netdev(struct net_device *dev);

-DECLARE_PER_CPU(int, xmit_recursion);
-#define XMIT_RECURSION_LIMIT 10
-
-static inline int dev_recursion_level(void)
-{
- return this_cpu_read(xmit_recursion);
-}
-
struct net_device *dev_get_by_index(struct net *net, int ifindex);
struct net_device *__dev_get_by_index(struct net *net, int ifindex);
struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
@@ -2967,6 +2959,11 @@ struct softnet_data {
#ifdef CONFIG_XFRM_OFFLOAD
struct sk_buff_head xfrm_backlog;
#endif
+ /* written and read only by owning cpu: */
+ struct {
+ u16 recursion;
+ u8 more;
+ } xmit;
#ifdef CONFIG_RPS
/* input_queue_head should be written by cpu owning this struct,
* and only read by other cpus. Worth using a cache line.
@@ -3002,6 +2999,28 @@ static inline void input_queue_tail_incr_save(struct softnet_data *sd,

DECLARE_PER_CPU_ALIGNED(struct softnet_data, softnet_data);

+static inline int dev_recursion_level(void)
+{
+ return __this_cpu_read(softnet_data.xmit.recursion);
+}
+
+#define XMIT_RECURSION_LIMIT 10
+static inline bool dev_xmit_recursion(void)
+{
+ return unlikely(__this_cpu_read(softnet_data.xmit.recursion) >
+ XMIT_RECURSION_LIMIT);
+}
+
+static inline void dev_xmit_recursion_inc(void)
+{
+ __this_cpu_inc(softnet_data.xmit.recursion);
+}
+
+static inline void dev_xmit_recursion_dec(void)
+{
+ __this_cpu_dec(softnet_data.xmit.recursion);
+}
+
void __netif_schedule(struct Qdisc *q);
void netif_schedule_queue(struct netdev_queue *txq);

@@ -4314,6 +4333,11 @@ static inline netdev_tx_t __netdev_start_xmit(const struct net_device_ops *ops,
return ops->ndo_start_xmit(skb, dev);
}

+static inline bool netdev_xmit_more(void)
+{
+ return __this_cpu_read(softnet_data.xmit.more);
+}
+
static inline netdev_tx_t netdev_start_xmit(struct sk_buff *skb, struct net_device *dev,
struct netdev_queue *txq, bool more)
{
diff --git a/net/core/dev.c b/net/core/dev.c
index 5e668d3b1e717..8f9a8b009a238 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3534,9 +3534,6 @@ static void skb_update_prio(struct sk_buff *skb)
#define skb_update_prio(skb)
#endif

-DEFINE_PER_CPU(int, xmit_recursion);
-EXPORT_SYMBOL(xmit_recursion);
-
/**
* dev_loopback_xmit - loop back @skb
* @net: network namespace this loopback is happening in
@@ -3827,8 +3824,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
int cpu = smp_processor_id(); /* ok because BHs are off */

if (txq->xmit_lock_owner != cpu) {
- if (unlikely(__this_cpu_read(xmit_recursion) >
- XMIT_RECURSION_LIMIT))
+ if (dev_xmit_recursion())
goto recursion_alert;

skb = validate_xmit_skb(skb, dev, &again);
@@ -3838,9 +3834,9 @@ static int __dev_queue_xmit(struct sk_buff *skb, struct net_device *sb_dev)
HARD_TX_LOCK(dev, txq, cpu);

if (!netif_xmit_stopped(txq)) {
- __this_cpu_inc(xmit_recursion);
+ dev_xmit_recursion_inc();
skb = dev_hard_start_xmit(skb, dev, txq, &rc);
- __this_cpu_dec(xmit_recursion);
+ dev_xmit_recursion_dec();
if (dev_xmit_complete(rc)) {
HARD_TX_UNLOCK(dev, txq);
goto out;
diff --git a/net/core/filter.c b/net/core/filter.c
index b5521b60a2d4f..636e67a928477 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -2002,7 +2002,7 @@ static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb)
{
int ret;

- if (unlikely(__this_cpu_read(xmit_recursion) > XMIT_RECURSION_LIMIT)) {
+ if (dev_xmit_recursion()) {
net_crit_ratelimited("bpf: recursion limit reached on datapath, buggy bpf program?\n");
kfree_skb(skb);
return -ENETDOWN;
@@ -2011,9 +2011,9 @@ static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb)
skb->dev = dev;
skb->tstamp = 0;

- __this_cpu_inc(xmit_recursion);
+ dev_xmit_recursion_inc();
ret = dev_queue_xmit(skb);
- __this_cpu_dec(xmit_recursion);
+ dev_xmit_recursion_dec();

return ret;
}
--
2.25.1