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net: bulk free SKBs that were delay free'ed due to IRQ context

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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>
This commit is contained in:
Jesper Dangaard Brouer 2016-02-08 13:15:04 +01:00 committed by David S. Miller
parent 795bb1c00d
commit 15fad714be
3 changed files with 14 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/linux/skbuff.h
View File

@ -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

8
net/core/dev.c
View File

@ -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) {

8
net/core/skbuff.c
View File

@ -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);