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net: dev: Makes sure netif_rx() can be invoked in any context.

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Dave suggested a while ago (eleven years by now) "Let's make netif_rx()
work in all contexts and get rid of netif_rx_ni()". Eric agreed and
pointed out that modern devices should use netif_receive_skb() to avoid
the overhead.
In the meantime someone added another variant, netif_rx_any_context(),
which behaves as suggested.

netif_rx() must be invoked with disabled bottom halves to ensure that
pending softirqs, which were raised within the function, are handled.
netif_rx_ni() can be invoked only from process context (bottom halves
must be enabled) because the function handles pending softirqs without
checking if bottom halves were disabled or not.
netif_rx_any_context() invokes on the former functions by checking
in_interrupts().

netif_rx() could be taught to handle both cases (disabled and enabled
bottom halves) by simply disabling bottom halves while invoking
netif_rx_internal(). The local_bh_enable() invocation will then invoke
pending softirqs only if the BH-disable counter drops to zero.

Eric is concerned about the overhead of BH-disable+enable especially in
regard to the loopback driver. As critical as this driver is, it will
receive a shortcut to avoid the additional overhead which is not needed.

Add a local_bh_disable() section in netif_rx() to ensure softirqs are
handled if needed.
Provide __netif_rx() which does not disable BH and has a lockdep assert
to ensure that interrupts are disabled. Use this shortcut in the
loopback driver and in drivers/net/*.c.
Make netif_rx_ni() and netif_rx_any_context() invoke netif_rx() so they
can be removed once they are no more users left.

Link: https://lkml.kernel.org/r/20100415.020246.218622820.davem@davemloft.net
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Sebastian Andrzej Siewior 2022-02-12 00:38:38 +01:00 committed by David S. Miller
parent f234ae2947
commit baebdf48c3
16 changed files with 60 additions and 73 deletions
repo.diff.show_diff_stats Download patch file Download diff file Expand all files Collapse all files

4
drivers/net/amt.c
View file

@ -2373,7 +2373,7 @@ static bool amt_membership_query_handler(struct amt_dev *amt,
skb->pkt_type = PACKET_MULTICAST;
skb->ip_summed = CHECKSUM_NONE;
len = skb->len;
if (netif_rx(skb) == NET_RX_SUCCESS) {
if (__netif_rx(skb) == NET_RX_SUCCESS) {
amt_update_gw_status(amt, AMT_STATUS_RECEIVED_QUERY, true);
dev_sw_netstats_rx_add(amt->dev, len);
} else {
@ -2470,7 +2470,7 @@ static bool amt_update_handler(struct amt_dev *amt, struct sk_buff *skb)
skb->pkt_type = PACKET_MULTICAST;
skb->ip_summed = CHECKSUM_NONE;
len = skb->len;
if (netif_rx(skb) == NET_RX_SUCCESS) {
if (__netif_rx(skb) == NET_RX_SUCCESS) {
amt_update_relay_status(tunnel, AMT_STATUS_RECEIVED_UPDATE,
true);
dev_sw_netstats_rx_add(amt->dev, len);

4
drivers/net/geneve.c
View file

@ -925,7 +925,7 @@ static int geneve_xmit_skb(struct sk_buff *skb, struct net_device *dev,
}
skb->protocol = eth_type_trans(skb, geneve->dev);
netif_rx(skb);
__netif_rx(skb);
dst_release(&rt->dst);
return -EMSGSIZE;
}
@ -1021,7 +1021,7 @@ static int geneve6_xmit_skb(struct sk_buff *skb, struct net_device *dev,
}
skb->protocol = eth_type_trans(skb, geneve->dev);
netif_rx(skb);
__netif_rx(skb);
dst_release(dst);
return -EMSGSIZE;
}

2
drivers/net/gtp.c
View file

@ -207,7 +207,7 @@ static int gtp_rx(struct pdp_ctx *pctx, struct sk_buff *skb,
dev_sw_netstats_rx_add(pctx->dev, skb->len);
netif_rx(skb);
__netif_rx(skb);
return 0;
err:

4
drivers/net/loopback.c
View file

@ -78,7 +78,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
skb_orphan(skb);
/* Before queueing this packet to netif_rx(),
/* Before queueing this packet to __netif_rx(),
* make sure dst is refcounted.
*/
skb_dst_force(skb);
@ -86,7 +86,7 @@ static netdev_tx_t loopback_xmit(struct sk_buff *skb,
skb->protocol = eth_type_trans(skb, dev);
len = skb->len;
if (likely(netif_rx(skb) == NET_RX_SUCCESS))
if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
dev_lstats_add(dev, len);
return NETDEV_TX_OK;

6
drivers/net/macsec.c
View file

@ -1033,7 +1033,7 @@ static enum rx_handler_result handle_not_macsec(struct sk_buff *skb)
else
nskb->pkt_type = PACKET_MULTICAST;
netif_rx(nskb);
__netif_rx(nskb);
}
continue;
}
@ -1056,7 +1056,7 @@ static enum rx_handler_result handle_not_macsec(struct sk_buff *skb)
nskb->dev = ndev;
if (netif_rx(nskb) == NET_RX_SUCCESS) {
if (__netif_rx(nskb) == NET_RX_SUCCESS) {
u64_stats_update_begin(&secy_stats->syncp);
secy_stats->stats.InPktsUntagged++;
u64_stats_update_end(&secy_stats->syncp);
@ -1288,7 +1288,7 @@ static rx_handler_result_t macsec_handle_frame(struct sk_buff **pskb)
macsec_reset_skb(nskb, macsec->secy.netdev);
ret = netif_rx(nskb);
ret = __netif_rx(nskb);
if (ret == NET_RX_SUCCESS) {
u64_stats_update_begin(&secy_stats->syncp);
secy_stats->stats.InPktsUnknownSCI++;

4
drivers/net/macvlan.c
View file

@ -410,7 +410,7 @@ static void macvlan_forward_source_one(struct sk_buff *skb,
if (ether_addr_equal_64bits(eth_hdr(skb)->h_dest, dev->dev_addr))
nskb->pkt_type = PACKET_HOST;
ret = netif_rx(nskb);
ret = __netif_rx(nskb);
macvlan_count_rx(vlan, len, ret == NET_RX_SUCCESS, false);
}
@ -468,7 +468,7 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
/* forward to original port. */
vlan = src;
ret = macvlan_broadcast_one(skb, vlan, eth, 0) ?:
netif_rx(skb);
__netif_rx(skb);
handle_res = RX_HANDLER_CONSUMED;
goto out;
}

2
drivers/net/mhi_net.c
View file

@ -225,7 +225,7 @@ static void mhi_net_dl_callback(struct mhi_device *mhi_dev,
u64_stats_inc(&mhi_netdev->stats.rx_packets);
u64_stats_add(&mhi_netdev->stats.rx_bytes, skb->len);
u64_stats_update_end(&mhi_netdev->stats.rx_syncp);
netif_rx(skb);
__netif_rx(skb);
}
/* Refill if RX buffers queue becomes low */

2
drivers/net/ntb_netdev.c
View file

@ -119,7 +119,7 @@ static void ntb_netdev_rx_handler(struct ntb_transport_qp *qp, void *qp_data,
skb->protocol = eth_type_trans(skb, ndev);
skb->ip_summed = CHECKSUM_NONE;
if (netif_rx(skb) == NET_RX_DROP) {
if (__netif_rx(skb) == NET_RX_DROP) {
ndev->stats.rx_errors++;
ndev->stats.rx_dropped++;
} else {

2
drivers/net/rionet.c
View file

@ -109,7 +109,7 @@ static int rionet_rx_clean(struct net_device *ndev)
skb_put(rnet->rx_skb[i], RIO_MAX_MSG_SIZE);
rnet->rx_skb[i]->protocol =
eth_type_trans(rnet->rx_skb[i], ndev);
error = netif_rx(rnet->rx_skb[i]);
error = __netif_rx(rnet->rx_skb[i]);
if (error == NET_RX_DROP) {
ndev->stats.rx_dropped++;

2
drivers/net/sb1000.c
View file

@ -872,7 +872,7 @@ printk("cm0: IP identification: %02x%02x fragment offset: %02x%02x\n", buffer[3
/* datagram completed: send to upper level */
skb_trim(skb, dlen);
netif_rx(skb);
__netif_rx(skb);
stats->rx_bytes+=dlen;
stats->rx_packets++;
lp->rx_skb[ns] = NULL;

2
drivers/net/veth.c
View file

@ -287,7 +287,7 @@ static int veth_forward_skb(struct net_device *dev, struct sk_buff *skb,
{
return __dev_forward_skb(dev, skb) ?: xdp ?
veth_xdp_rx(rq, skb) :
netif_rx(skb);
__netif_rx(skb);
}
/* return true if the specified skb has chances of GRO aggregation

2
drivers/net/vrf.c
View file

@ -418,7 +418,7 @@ static int vrf_local_xmit(struct sk_buff *skb, struct net_device *dev,
skb->protocol = eth_type_trans(skb, dev);
if (likely(netif_rx(skb) == NET_RX_SUCCESS))
if (likely(__netif_rx(skb) == NET_RX_SUCCESS))
vrf_rx_stats(dev, len);
else
this_cpu_inc(dev->dstats->rx_drps);

2
drivers/net/vxlan.c
View file

@ -2541,7 +2541,7 @@ static void vxlan_encap_bypass(struct sk_buff *skb, struct vxlan_dev *src_vxlan,
tx_stats->tx_bytes += len;
u64_stats_update_end(&tx_stats->syncp);
if (netif_rx(skb) == NET_RX_SUCCESS) {
if (__netif_rx(skb) == NET_RX_SUCCESS) {
u64_stats_update_begin(&rx_stats->syncp);
rx_stats->rx_packets++;
rx_stats->rx_bytes += len;

14
include/linux/netdevice.h
View file

@ -3672,8 +3672,18 @@ u32 bpf_prog_run_generic_xdp(struct sk_buff *skb, struct xdp_buff *xdp,
void generic_xdp_tx(struct sk_buff *skb, struct bpf_prog *xdp_prog);
int do_xdp_generic(struct bpf_prog *xdp_prog, struct sk_buff *skb);
int netif_rx(struct sk_buff *skb);
int netif_rx_ni(struct sk_buff *skb);
int netif_rx_any_context(struct sk_buff *skb);
int __netif_rx(struct sk_buff *skb);
static inline int netif_rx_ni(struct sk_buff *skb)
{
return netif_rx(skb);
}
static inline int netif_rx_any_context(struct sk_buff *skb)
{
return netif_rx(skb);
}
int netif_receive_skb(struct sk_buff *skb);
int netif_receive_skb_core(struct sk_buff *skb);
void netif_receive_skb_list_internal(struct list_head *head);

14
include/trace/events/net.h
View file

@ -260,13 +260,6 @@ DEFINE_EVENT(net_dev_rx_verbose_template, netif_rx_entry,
TP_ARGS(skb)
);
DEFINE_EVENT(net_dev_rx_verbose_template, netif_rx_ni_entry,
TP_PROTO(const struct sk_buff *skb),
TP_ARGS(skb)
);
DECLARE_EVENT_CLASS(net_dev_rx_exit_template,
TP_PROTO(int ret),
@ -312,13 +305,6 @@ DEFINE_EVENT(net_dev_rx_exit_template, netif_rx_exit,
TP_ARGS(ret)
);
DEFINE_EVENT(net_dev_rx_exit_template, netif_rx_ni_exit,
TP_PROTO(int ret),
TP_ARGS(ret)
);
DEFINE_EVENT(net_dev_rx_exit_template, netif_receive_skb_list_exit,
TP_PROTO(int ret),

67
net/core/dev.c
View file

@ -4815,66 +4815,57 @@ static int netif_rx_internal(struct sk_buff *skb)
return ret;
}
/**
* __netif_rx - Slightly optimized version of netif_rx
* @skb: buffer to post
*
* This behaves as netif_rx except that it does not disable bottom halves.
* As a result this function may only be invoked from the interrupt context
* (either hard or soft interrupt).
*/
int __netif_rx(struct sk_buff *skb)
{
int ret;
lockdep_assert_once(hardirq_count() | softirq_count());
trace_netif_rx_entry(skb);
ret = netif_rx_internal(skb);
trace_netif_rx_exit(ret);
return ret;
}
EXPORT_SYMBOL(__netif_rx);
/**
* netif_rx - post buffer to the network code
* @skb: buffer to post
*
* This function receives a packet from a device driver and queues it for
* the upper (protocol) levels to process. It always succeeds. The buffer
* may be dropped during processing for congestion control or by the
* protocol layers.
* the upper (protocol) levels to process via the backlog NAPI device. It
* always succeeds. The buffer may be dropped during processing for
* congestion control or by the protocol layers.
* The network buffer is passed via the backlog NAPI device. Modern NIC
* driver should use NAPI and GRO.
* This function can used from any context.
*
* return values:
* NET_RX_SUCCESS (no congestion)
* NET_RX_DROP (packet was dropped)
*
*/
int netif_rx(struct sk_buff *skb)
{
int ret;
local_bh_disable();
trace_netif_rx_entry(skb);
ret = netif_rx_internal(skb);
trace_netif_rx_exit(ret);
local_bh_enable();
return ret;
}
EXPORT_SYMBOL(netif_rx);
int netif_rx_ni(struct sk_buff *skb)
{
int err;
trace_netif_rx_ni_entry(skb);
preempt_disable();
err = netif_rx_internal(skb);
if (local_softirq_pending())
do_softirq();
preempt_enable();
trace_netif_rx_ni_exit(err);
return err;
}
EXPORT_SYMBOL(netif_rx_ni);
int netif_rx_any_context(struct sk_buff *skb)
{
/*
* If invoked from contexts which do not invoke bottom half
* processing either at return from interrupt or when softrqs are
* reenabled, use netif_rx_ni() which invokes bottomhalf processing
* directly.
*/
if (in_interrupt())
return netif_rx(skb);
else
return netif_rx_ni(skb);
}
EXPORT_SYMBOL(netif_rx_any_context);
static __latent_entropy void net_tx_action(struct softirq_action *h)
{
struct softnet_data *sd = this_cpu_ptr(&softnet_data);