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Commit 9754e293 authored by David S. Miller's avatar David S. Miller
Browse files

net: Don't write to current task flags on every packet received. 



Even for non-pfmalloc SKBs, __netif_receive_skb() will do a
tsk_restore_flags() on current unconditionally.

Make __netif_receive_skb() a shim around the existing code, renamed to
__netif_receive_skb_core().  Let __netif_receive_skb() wrap the
__netif_receive_skb_core() call with the task flag modifications, if
necessary.

Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent ba779711

net/core/dev.c

+28 −18
Original line number Diff line number Diff line
@@ -3457,7 +3457,7 @@ static bool skb_pfmemalloc_protocol(struct sk_buff *skb) 
	}

}



static int __netif_receive_skb(struct sk_buff *skb)

static int __netif_receive_skb_core(struct sk_buff *skb, bool pfmemalloc)

{

	struct packet_type *ptype, *pt_prev;

	rx_handler_func_t *rx_handler;
@@ -3466,24 +3466,11 @@ static int __netif_receive_skb(struct sk_buff *skb) 
	bool deliver_exact = false;

	int ret = NET_RX_DROP;

	__be16 type;

	unsigned long pflags = current->flags;



	net_timestamp_check(!netdev_tstamp_prequeue, skb);



	trace_netif_receive_skb(skb);



	/*

	 * PFMEMALLOC skbs are special, they should

	 * - be delivered to SOCK_MEMALLOC sockets only

	 * - stay away from userspace

	 * - have bounded memory usage

	 *

	 * Use PF_MEMALLOC as this saves us from propagating the allocation

	 * context down to all allocation sites.

	 */

	if (sk_memalloc_socks() && skb_pfmemalloc(skb))

		current->flags |= PF_MEMALLOC;



	/* if we've gotten here through NAPI, check netpoll */

	if (netpoll_receive_skb(skb))

		goto out;
@@ -3517,7 +3504,7 @@ static int __netif_receive_skb(struct sk_buff *skb) 
	}

#endif



	if (sk_memalloc_socks() && skb_pfmemalloc(skb))

	if (pfmemalloc)

		goto skip_taps;



	list_for_each_entry_rcu(ptype, &ptype_all, list) {
@@ -3536,8 +3523,7 @@ static int __netif_receive_skb(struct sk_buff *skb) 
ncls:

#endif



	if (sk_memalloc_socks() && skb_pfmemalloc(skb)

				&& !skb_pfmemalloc_protocol(skb))

	if (pfmemalloc && !skb_pfmemalloc_protocol(skb))

		goto drop;



	if (vlan_tx_tag_present(skb)) {
@@ -3607,7 +3593,31 @@ static int __netif_receive_skb(struct sk_buff *skb) 
unlock:

	rcu_read_unlock();

out:

	return ret;

}



static int __netif_receive_skb(struct sk_buff *skb)

{

	int ret;



	if (sk_memalloc_socks() && skb_pfmemalloc(skb)) {

		unsigned long pflags = current->flags;



		/*

		 * PFMEMALLOC skbs are special, they should

		 * - be delivered to SOCK_MEMALLOC sockets only

		 * - stay away from userspace

		 * - have bounded memory usage

		 *

		 * Use PF_MEMALLOC as this saves us from propagating the allocation

		 * context down to all allocation sites.

		 */

		current->flags |= PF_MEMALLOC;

		ret = __netif_receive_skb_core(skb, true);

		tsk_restore_flags(current, pflags, PF_MEMALLOC);

	} else

		ret = __netif_receive_skb_core(skb, false);



	return ret;

}