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163 lines
4.7 KiB
Diff
163 lines
4.7 KiB
Diff
From 5fb53f2940525ef6ad39acc8f612e657bd7cbea7 Mon Sep 17 00:00:00 2001
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From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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Date: Wed, 13 Jan 2016 15:55:02 +0100
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Subject: [PATCH 323/414] net: move xmit_recursion to per-task variable on -RT
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A softirq on -RT can be preempted. That means one task is in
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__dev_queue_xmit(), gets preempted and another task may enter
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__dev_queue_xmit() aw well. netperf together with a bridge device
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will then trigger the `recursion alert` because each task increments
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the xmit_recursion variable which is per-CPU.
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A virtual device like br0 is required to trigger this warning.
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This patch moves the counter to per task instead per-CPU so it counts
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the recursion properly on -RT.
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Cc: stable-rt@vger.kernel.org
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Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
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---
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include/linux/netdevice.h | 41 ++++++++++++++++++++++++++++++++++++++-
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include/linux/sched.h | 3 +++
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net/core/dev.c | 9 +++++----
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net/core/filter.c | 6 +++---
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4 files changed, 51 insertions(+), 8 deletions(-)
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diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
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index a5e88b07a471..03d01f91df83 100644
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--- a/include/linux/netdevice.h
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+++ b/include/linux/netdevice.h
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@@ -2433,14 +2433,53 @@ void netdev_freemem(struct net_device *dev);
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void synchronize_net(void);
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int init_dummy_netdev(struct net_device *dev);
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-DECLARE_PER_CPU(int, xmit_recursion);
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#define XMIT_RECURSION_LIMIT 10
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+static inline int dev_recursion_level(void)
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+{
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+ return current->xmit_recursion;
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+}
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+
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+static inline int xmit_rec_read(void)
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+{
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+ return current->xmit_recursion;
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+}
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+
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+static inline void xmit_rec_inc(void)
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+{
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+ current->xmit_recursion++;
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+}
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+
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+static inline void xmit_rec_dec(void)
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+{
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+ current->xmit_recursion--;
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+}
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+
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+#else
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+
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+DECLARE_PER_CPU(int, xmit_recursion);
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static inline int dev_recursion_level(void)
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{
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return this_cpu_read(xmit_recursion);
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}
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+static inline int xmit_rec_read(void)
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+{
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+ return __this_cpu_read(xmit_recursion);
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+}
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+
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+static inline void xmit_rec_inc(void)
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+{
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+ __this_cpu_inc(xmit_recursion);
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+}
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+
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+static inline void xmit_rec_dec(void)
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+{
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+ __this_cpu_dec(xmit_recursion);
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+}
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+#endif
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+
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struct net_device *dev_get_by_index(struct net *net, int ifindex);
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struct net_device *__dev_get_by_index(struct net *net, int ifindex);
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struct net_device *dev_get_by_index_rcu(struct net *net, int ifindex);
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diff --git a/include/linux/sched.h b/include/linux/sched.h
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index 358748c77304..f6ea03d86966 100644
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--- a/include/linux/sched.h
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+++ b/include/linux/sched.h
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@@ -1115,6 +1115,9 @@ struct task_struct {
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#endif
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#ifdef CONFIG_DEBUG_ATOMIC_SLEEP
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unsigned long task_state_change;
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+#endif
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+#ifdef CONFIG_PREEMPT_RT_FULL
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+ int xmit_recursion;
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#endif
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int pagefault_disabled;
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#ifdef CONFIG_MMU
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diff --git a/net/core/dev.c b/net/core/dev.c
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index bcbc5b2b2d3f..b39e7672062a 100644
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--- a/net/core/dev.c
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+++ b/net/core/dev.c
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@@ -3248,8 +3248,10 @@ static void skb_update_prio(struct sk_buff *skb)
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#define skb_update_prio(skb)
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#endif
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+#ifndef CONFIG_PREEMPT_RT_FULL
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DEFINE_PER_CPU(int, xmit_recursion);
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EXPORT_SYMBOL(xmit_recursion);
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+#endif
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/**
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* dev_loopback_xmit - loop back @skb
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@@ -3490,8 +3492,7 @@ static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
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int cpu = smp_processor_id(); /* ok because BHs are off */
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if (txq->xmit_lock_owner != cpu) {
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- if (unlikely(__this_cpu_read(xmit_recursion) >
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- XMIT_RECURSION_LIMIT))
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+ if (unlikely(xmit_rec_read() > XMIT_RECURSION_LIMIT))
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goto recursion_alert;
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skb = validate_xmit_skb(skb, dev);
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@@ -3501,9 +3502,9 @@ static int __dev_queue_xmit(struct sk_buff *skb, void *accel_priv)
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HARD_TX_LOCK(dev, txq, cpu);
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if (!netif_xmit_stopped(txq)) {
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- __this_cpu_inc(xmit_recursion);
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+ xmit_rec_inc();
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skb = dev_hard_start_xmit(skb, dev, txq, &rc);
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- __this_cpu_dec(xmit_recursion);
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+ xmit_rec_dec();
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if (dev_xmit_complete(rc)) {
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HARD_TX_UNLOCK(dev, txq);
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goto out;
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diff --git a/net/core/filter.c b/net/core/filter.c
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index d5158a10ac8f..ad96ec78f7b8 100644
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--- a/net/core/filter.c
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+++ b/net/core/filter.c
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@@ -1696,7 +1696,7 @@ static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb)
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{
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int ret;
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- if (unlikely(__this_cpu_read(xmit_recursion) > XMIT_RECURSION_LIMIT)) {
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+ if (unlikely(xmit_rec_read() > XMIT_RECURSION_LIMIT)) {
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net_crit_ratelimited("bpf: recursion limit reached on datapath, buggy bpf program?\n");
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kfree_skb(skb);
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return -ENETDOWN;
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@@ -1704,9 +1704,9 @@ static inline int __bpf_tx_skb(struct net_device *dev, struct sk_buff *skb)
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skb->dev = dev;
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- __this_cpu_inc(xmit_recursion);
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+ xmit_rec_inc();
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ret = dev_queue_xmit(skb);
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- __this_cpu_dec(xmit_recursion);
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+ xmit_rec_dec();
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return ret;
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}
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--
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2.17.0
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