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: David S. Miller <davem@davemloft.net>
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 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 @@
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 @@
}
#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 @@
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 @@
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;
}