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Message-Id: <20220211233839.2280731-3-bigeasy@linutronix.de>
Date: Sat, 12 Feb 2022 00:38:38 +0100
From: Sebastian Andrzej Siewior <bigeasy@...utronix.de>
To: bpf@...r.kernel.org, netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
Alexei Starovoitov <ast@...nel.org>,
Daniel Borkmann <daniel@...earbox.net>,
Eric Dumazet <edumazet@...gle.com>,
Jakub Kicinski <kuba@...nel.org>,
Jesper Dangaard Brouer <hawk@...nel.org>,
John Fastabend <john.fastabend@...il.com>,
Thomas Gleixner <tglx@...utronix.de>,
Toke Høiland-Jørgensen <toke@...e.dk>,
Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
Toke Høiland-Jørgensen <toke@...hat.com>
Subject: [PATCH net-next v3 2/3] net: dev: Makes sure netif_rx() can be invoked in any context.
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@...utronix.de>
Reviewed-by: Eric Dumazet <edumazet@...gle.com>
Reviewed-by: Toke Høiland-Jørgensen <toke@...hat.com>
---
drivers/net/amt.c | 4 +--
drivers/net/geneve.c | 4 +--
drivers/net/gtp.c | 2 +-
drivers/net/loopback.c | 4 +--
drivers/net/macsec.c | 6 ++--
drivers/net/macvlan.c | 4 +--
drivers/net/mhi_net.c | 2 +-
drivers/net/ntb_netdev.c | 2 +-
drivers/net/rionet.c | 2 +-
drivers/net/sb1000.c | 2 +-
drivers/net/veth.c | 2 +-
drivers/net/vrf.c | 2 +-
drivers/net/vxlan.c | 2 +-
include/linux/netdevice.h | 14 ++++++--
include/trace/events/net.h | 14 --------
net/core/dev.c | 67 +++++++++++++++++---------------------
16 files changed, 60 insertions(+), 73 deletions(-)
diff --git a/drivers/net/amt.c b/drivers/net/amt.c
index f1a36d7e2151c..10455c9b9da0e 100644
--- a/drivers/net/amt.c
+++ b/drivers/net/amt.c
@@ -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);
diff --git a/drivers/net/geneve.c b/drivers/net/geneve.c
index c1fdd721a730d..a895ff756093a 100644
--- a/drivers/net/geneve.c
+++ b/drivers/net/geneve.c
@@ -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;
}
diff --git a/drivers/net/gtp.c b/drivers/net/gtp.c
index 24e5c54d06c15..bf087171bcf04 100644
--- a/drivers/net/gtp.c
+++ b/drivers/net/gtp.c
@@ -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:
diff --git a/drivers/net/loopback.c b/drivers/net/loopback.c
index ed0edf5884ef8..d05f86fe78c95 100644
--- a/drivers/net/loopback.c
+++ b/drivers/net/loopback.c
@@ -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;
diff --git a/drivers/net/macsec.c b/drivers/net/macsec.c
index 3d08743317634..832f09ac075e7 100644
--- a/drivers/net/macsec.c
+++ b/drivers/net/macsec.c
@@ -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++;
diff --git a/drivers/net/macvlan.c b/drivers/net/macvlan.c
index 6ef5f77be4d0a..d87c06c317ede 100644
--- a/drivers/net/macvlan.c
+++ b/drivers/net/macvlan.c
@@ -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;
}
diff --git a/drivers/net/mhi_net.c b/drivers/net/mhi_net.c
index aaa628f859fd4..0b1b6f650104b 100644
--- a/drivers/net/mhi_net.c
+++ b/drivers/net/mhi_net.c
@@ -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 */
diff --git a/drivers/net/ntb_netdev.c b/drivers/net/ntb_netdev.c
index 98ca6b18415e7..80bdc07f2cd33 100644
--- a/drivers/net/ntb_netdev.c
+++ b/drivers/net/ntb_netdev.c
@@ -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 {
diff --git a/drivers/net/rionet.c b/drivers/net/rionet.c
index 1a95f3beb784d..39e61e07e4894 100644
--- a/drivers/net/rionet.c
+++ b/drivers/net/rionet.c
@@ -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++;
diff --git a/drivers/net/sb1000.c b/drivers/net/sb1000.c
index 57a6d598467b2..c3f8020571add 100644
--- a/drivers/net/sb1000.c
+++ b/drivers/net/sb1000.c
@@ -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;
diff --git a/drivers/net/veth.c b/drivers/net/veth.c
index 354a963075c5f..6754fb8d9fabc 100644
--- a/drivers/net/veth.c
+++ b/drivers/net/veth.c
@@ -286,7 +286,7 @@ 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
diff --git a/drivers/net/vrf.c b/drivers/net/vrf.c
index e0b1ab99a359e..714cafcf6c6c8 100644
--- a/drivers/net/vrf.c
+++ b/drivers/net/vrf.c
@@ -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);
diff --git a/drivers/net/vxlan.c b/drivers/net/vxlan.c
index 359d16780dbbc..d0dc90d3dac28 100644
--- a/drivers/net/vxlan.c
+++ b/drivers/net/vxlan.c
@@ -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;
diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index e490b84732d16..c9e883104adb1 100644
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -3669,8 +3669,18 @@ 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);
diff --git a/include/trace/events/net.h b/include/trace/events/net.h
index 78c448c6ab4c5..032b431b987b6 100644
--- a/include/trace/events/net.h
+++ b/include/trace/events/net.h
@@ -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),
diff --git a/net/core/dev.c b/net/core/dev.c
index 0d13340ed4054..7d90f565e540a 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -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);
--
2.34.1
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