From 15fad714be86eab13e7568fecaf475b2a9730d3e Mon Sep 17 00:00:00 2001
From: Jesper Dangaard Brouer <brouer@redhat.com>
Date: Mon, 8 Feb 2016 13:15:04 +0100
Subject: [PATCH] net: bulk free SKBs that were delay free'ed due to IRQ
context
The network stack defers SKBs free, in-case free happens in IRQ or
when IRQs are disabled. This happens in __dev_kfree_skb_irq() that
writes SKBs that were free'ed during IRQ to the softirq completion
queue (softnet_data.completion_queue).
These SKBs are naturally delayed, and cleaned up during NET_TX_SOFTIRQ
in function net_tx_action(). Take advantage of this a use the skb
defer and flush API, as we are already in softirq context.
For modern drivers this rarely happens. Although most drivers do call
dev_kfree_skb_any(), which detects the situation and calls
__dev_kfree_skb_irq() when needed. This due to netpoll can call from
IRQ context.
Signed-off-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
---
include/linux/skbuff.h | 1 +
net/core/dev.c | 8 +++++++-
net/core/skbuff.c | 8 ++++++--
3 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index b56c0103fa15e..6ec86f1a2ed96 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2407,6 +2407,7 @@ static inline struct sk_buff *napi_alloc_skb(struct napi_struct *napi,
void napi_consume_skb(struct sk_buff *skb, int budget);
void __kfree_skb_flush(void);
+void __kfree_skb_defer(struct sk_buff *skb);
/**
* __dev_alloc_pages - allocate page for network Rx
diff --git a/net/core/dev.c b/net/core/dev.c
index 9b2c7a999e714..3f4071a84a03f 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -3829,8 +3829,14 @@ static void net_tx_action(struct softirq_action *h)
trace_consume_skb(skb);
else
trace_kfree_skb(skb, net_tx_action);
- __kfree_skb(skb);
+
+ if (skb->fclone != SKB_FCLONE_UNAVAILABLE)
+ __kfree_skb(skb);
+ else
+ __kfree_skb_defer(skb);
}
+
+ __kfree_skb_flush();
}
if (sd->output_queue) {
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index b64187b877738..a5bd067ec1a3b 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -767,7 +767,7 @@ void __kfree_skb_flush(void)
}
}
-static void __kfree_skb_defer(struct sk_buff *skb)
+static inline void _kfree_skb_defer(struct sk_buff *skb)
{
struct napi_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
@@ -789,6 +789,10 @@ static void __kfree_skb_defer(struct sk_buff *skb)
nc->skb_count = 0;
}
}
+void __kfree_skb_defer(struct sk_buff *skb)
+{
+ _kfree_skb_defer(skb);
+}
void napi_consume_skb(struct sk_buff *skb, int budget)
{
@@ -814,7 +818,7 @@ void napi_consume_skb(struct sk_buff *skb, int budget)
return;
}
- __kfree_skb_defer(skb);
+ _kfree_skb_defer(skb);
}
EXPORT_SYMBOL(napi_consume_skb);
--
2.30.2