[PATCH net-next] net: Don't write to current task flags on every packet received.
From: David Miller <davem@davemloft.net>
Date: 2013-02-14 20:58:27
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
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: David S. Miller <davem@davemloft.net> --- I'll commit this after I do a bunch of tests. net/core/dev.c | 46 ++++++++++++++++++++++++++++------------------ 1 file changed, 28 insertions(+), 18 deletions(-)
diff --git a/net/core/dev.c b/net/core/dev.c
index 2f31bf9..f444736 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c@@ -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 @@ another_round: } #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 @@ skip_taps: 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 @@ drop: unlock: rcu_read_unlock(); out: - tsk_restore_flags(current, pflags, PF_MEMALLOC); + 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; }
--
1.7.11.7