linux.git/drivers/net/loopback.c, branch v5.18

net: Add skb_clear_tstamp() to keep the mono delivery_time

2022-03-03T14:38:48+00:00

Right now, skb->tstamp is reset to 0 whenever the skb is forwarded.

If skb->tstamp has the mono delivery_time, clearing it can hurt
the performance when it finally transmits out to fq@phy-dev.

The earlier patch added a skb->mono_delivery_time bit to
flag the skb->tstamp carrying the mono delivery_time.

This patch adds skb_clear_tstamp() helper which keeps
the mono delivery_time and clears everything else.

The delivery_time clearing will be postponed until the stack knows the
skb will be delivered locally.  It will be done in a latter patch.

Signed-off-by: Martin KaFai Lau 
Signed-off-by: David S. Miller

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

2022-02-14T13:38:35+00:00

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 
Reviewed-by: Eric Dumazet 
Reviewed-by: Toke Høiland-Jørgensen 
Signed-off-by: David S. Miller

net: Don't include filter.h from net/sock.h

2021-12-29T16:48:14+00:00

sock.h is pretty heavily used (5k objects rebuilt on x86 after
it's touched). We can drop the include of filter.h from it and
add a forward declaration of struct sk_filter instead.
This decreases the number of rebuilt objects when bpf.h
is touched from ~5k to ~1k.

There's a lot of missing includes this was masking. Primarily
in networking tho, this time.

Signed-off-by: Jakub Kicinski 
Signed-off-by: Alexei Starovoitov 
Acked-by: Marc Kleine-Budde 
Acked-by: Florian Fainelli 
Acked-by: Nikolay Aleksandrov 
Acked-by: Stefano Garzarella 
Link: https://lore.kernel.org/bpf/20211229004913.513372-1-kuba@kernel.org

net: use u64_stats_t in struct pcpu_lstats

2019-11-08T04:03:08+00:00

In order to fix the data-race found by KCSAN, we
can use the new u64_stats_t type and its accessors instead
of plain u64 fields. This will still generate optimal code
for both 32 and 64 bit platforms.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: provide dev_lstats_add() helper

2019-11-08T04:03:08+00:00

Many network drivers need it and hand-coded the same function.

In order to ease u64_stats_t adoption, it is time to factorize.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

net: provide dev_lstats_read() helper

2019-11-08T04:03:08+00:00

Many network drivers use hand-coded implementation of the same thing,
let's factorize things so that u64_stats_t adoption is done once.

Signed-off-by: Eric Dumazet 
Signed-off-by: David S. Miller

loopback: fix lockdep splat

2019-07-03T18:24:38+00:00

dev_init_scheduler() and dev_activate() expect the caller to
hold RTNL. Since we don't want blackhole device to be initialized
per ns, we are initializing at init.

[    3.855027] Call Trace:
[    3.855034]  dump_stack+0x67/0x95
[    3.855037]  lockdep_rcu_suspicious+0xd5/0x110
[    3.855044]  dev_init_scheduler+0xe3/0x120
[    3.855048]  ? net_olddevs_init+0x60/0x60
[    3.855050]  blackhole_netdev_init+0x45/0x6e
[    3.855052]  do_one_initcall+0x6c/0x2fa
[    3.855058]  ? rcu_read_lock_sched_held+0x8c/0xa0
[    3.855066]  kernel_init_freeable+0x1e5/0x288
[    3.855071]  ? rest_init+0x260/0x260
[    3.855074]  kernel_init+0xf/0x180
[    3.855076]  ? rest_init+0x260/0x260
[    3.855078]  ret_from_fork+0x24/0x30

Fixes: 4de83b88c66 ("loopback: create blackhole net device similar to loopack.")
Reported-by: Geert Uytterhoeven 
Cc: Eric Dumazet 
Signed-off-by: Mahesh Bandewar 
Tested-by: Geert Uytterhoeven 
Signed-off-by: David S. Miller

loopback: create blackhole net device similar to loopack.

2019-07-02T02:34:46+00:00

Create a blackhole net device that can be used for "dead"
dst entries instead of loopback device. This blackhole device differs
from loopback in few aspects: (a) It's not per-ns. (b)  MTU on this
device is ETH_MIN_MTU (c) The xmit function is essentially kfree_skb().
and (d) since it's not registered it won't have ifindex.

Lower MTU effectively make the device not pass the MTU check during
the route check when a dst associated with the skb is dead.

Signed-off-by: Mahesh Bandewar 
Signed-off-by: David S. Miller

treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 152

2019-05-30T18:26:32+00:00

Based on 1 normalized pattern(s):

  this program is free software you can redistribute it and or modify
  it under the terms of the gnu general public license as published by
  the free software foundation either version 2 of the license or at
  your option any later version

extracted by the scancode license scanner the SPDX license identifier

  GPL-2.0-or-later

has been chosen to replace the boilerplate/reference in 3029 file(s).

Signed-off-by: Thomas Gleixner 
Reviewed-by: Allison Randal 
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman

net: loopback: use generic helper to report timestamping info

2019-04-12T23:26:37+00:00

For reporting the common set of SW timestamping capabilities, use
ethtool_op_get_ts_info() instead of re-implementing it.

Signed-off-by: Julian Wiedmann 
Signed-off-by: David S. Miller