linux-toradex.git/include/linux/netpoll.h, branch v6.16-rc6

netconsole: allow selection of egress interface via MAC address

2025-03-19T18:17:58+00:00

Currently, netconsole has two methods of configuration - module
parameter and configfs. The former interface allows for netconsole
activation earlier during boot (by specifying the module parameter on
the kernel command line), so it is preferred for debugging issues which
arise before userspace is up/the configfs interface can be used. The
module parameter syntax requires specifying the egress interface name.
This requirement makes it hard to use for a couple reasons:
- The egress interface name can be hard or impossible to predict. For
  example, installing a new network card in a system can change the
  interface names assigned by the kernel.
- When constructing the module parameter, one may have trouble
  determining the original (kernel-assigned) name of the interface
  (which is the name that should be given to netconsole) if some stable
  interface naming scheme is in effect. A human can usually look at
  kernel logs to determine the original name, but this is very painful
  if automation is constructing the parameter.

For these reasons, allow selection of the egress interface via MAC
address when configuring netconsole using the module parameter. Update
the netconsole documentation with an example of the new syntax.
Selection of egress interface by MAC address via configfs is far less
interesting (since when this interface can be used, one should be able
to easily convert between MAC address and interface name), so it is left
unimplemented.

Signed-off-by: Uday Shankar 
Reviewed-by: Breno Leitao 
Tested-by: Breno Leitao 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20250312-netconsole-v6-2-3437933e79b8@purestorage.com
Signed-off-by: Paolo Abeni

netpoll: Optimize skb refilling on critical path

2025-03-08T03:55:40+00:00

netpoll tries to refill the skb queue on every packet send, independently
if packets are being consumed from the pool or not. This was
particularly problematic while being called from printk(), where the
operation would be done while holding the console lock.

Introduce a more intelligent approach to skb queue management. Instead
of constantly attempting to refill the queue, the system now defers
refilling to a work queue and only triggers the workqueue when a buffer
is actually dequeued. This change significantly reduces operations with
the lock held.

Add a work_struct to the netpoll structure for asynchronous refilling,
updating find_skb() to schedule refill work only when necessary (skb is
dequeued).

These changes have demonstrated a 15% reduction in time spent during
netpoll_send_msg operations, especially when no SKBs are not consumed
from consumed from pool.

When SKBs are being dequeued, the improvement is even better, around
70%, mainly because refilling the SKB pool is now happening outside of
the critical patch (with console_owner lock held).

Signed-off-by: Breno Leitao 
Reviewed-by: Simon Horman 
Link: https://patch.msgid.link/20250304-netpoll_refill_v2-v1-1-06e2916a4642@debian.org
Signed-off-by: Jakub Kicinski

netpoll: Make netpoll_send_udp return status instead of void

2024-12-05T03:15:38+00:00

netpoll_send_udp can return if send was successful.
It will allow client code to be aware of the send status.

Possible return values are the result of __netpoll_send_skb (cast to int)
and -ENOMEM. This doesn't cover the case when TX was not successful
instantaneously and was scheduled for later, __netpoll__send_skb returns
success in that case.

Signed-off-by: Maksym Kutsevol 
Link: https://patch.msgid.link/20241202-netcons-add-udp-send-fail-statistics-to-netconsole-v5-1-70e82239f922@kutsevol.com
Signed-off-by: Jakub Kicinski

Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net

2024-11-19T12:56:02+00:00

Merge in late fixes to prepare for the 6.13 net-next PR.

Conflicts:

include/linux/phy.h
  41ffcd95015f net: phy: fix phylib's dual eee_enabled
  721aa69e708b net: phy: convert eee_broken_modes to a linkmode bitmap
https://lore.kernel.org/all/20241118135512.1039208b@canb.auug.org.au/

drivers/net/ethernet/wangxun/txgbe/txgbe_phy.c
  2160428bcb20 net: txgbe: fix null pointer to pcs
  2160428bcb20 net: txgbe: remove GPIO interrupt controller

Adjacent commits:

include/linux/phy.h
  41ffcd95015f net: phy: fix phylib's dual eee_enabled
  516a5f11eb97 net: phy: respect cached advertising when re-enabling EEE

Signed-off-by: Paolo Abeni

netpoll: Use rcu_access_pointer() in netpoll_poll_lock

2024-11-19T03:01:39+00:00

The ndev->npinfo pointer in netpoll_poll_lock() is RCU-protected but is
being accessed directly for a NULL check. While no RCU read lock is held
in this context, we should still use proper RCU primitives for
consistency and correctness.

Replace the direct NULL check with rcu_access_pointer(), which is the
appropriate primitive when only checking for NULL without dereferencing
the pointer. This function provides the necessary ordering guarantees
without requiring RCU read-side protection.

Fixes: bea3348eef27 ("[NET]: Make NAPI polling independent of struct net_device objects.")
Signed-off-by: Breno Leitao 
Reviewed-by: Michal Kubiak 
Link: https://patch.msgid.link/20241118-netpoll_rcu-v1-2-a1888dcb4a02@debian.org
Signed-off-by: Jakub Kicinski

net: netpoll: Individualize the skb pool

2024-11-16T00:25:34+00:00

The current implementation of the netpoll system uses a global skb
pool, which can lead to inefficient memory usage and
waste when targets are disabled or no longer in use.

This can result in a significant amount of memory being unnecessarily
allocated and retained, potentially causing performance issues and
limiting the availability of resources for other system components.

Modify the netpoll system to assign a skb pool to each target instead of
using a global one.

This approach allows for more fine-grained control over memory
allocation and deallocation, ensuring that resources are only allocated
and retained as needed.

Signed-off-by: Breno Leitao 
Link: https://patch.msgid.link/20241114-skb_buffers_v2-v3-1-9be9f52a8b69@debian.org
Signed-off-by: Jakub Kicinski

net: netpoll: extract core of netpoll_cleanup

2024-08-13T08:58:58+00:00

Extract the core part of netpoll_cleanup(), so, it could be called from
a caller that has the rtnl lock already.

Netconsole uses this in a weird way right now:

	__netpoll_cleanup(&nt->np);
	spin_lock_irqsave(&target_list_lock, flags);
	netdev_put(nt->np.dev, &nt->np.dev_tracker);
	nt->np.dev = NULL;
	nt->enabled = false;

This will be replaced by do_netpoll_cleanup() as the locking situation
is overhauled.

Signed-off-by: Breno Leitao 
Reviewed-by: Rik van Riel 
Signed-off-by: Paolo Abeni

netpoll: add net device refcount tracker to struct netpoll

2021-12-07T00:06:02+00:00

Signed-off-by: Eric Dumazet 
Signed-off-by: Jakub Kicinski

netpoll: Remove unused inline function netpoll_netdev_init()

2020-07-15T14:45:25+00:00

commit d565b0a1a9b6 ("net: Add Generic Receive Offload infrastructure")
left behind this, remove it.

Signed-off-by: YueHaibing 
Signed-off-by: David S. Miller

netpoll: netpoll_send_skb() returns transmit status

2020-05-08T01:11:07+00:00

Some callers want to know if the packet has been sent or
dropped, to inform upper stacks.

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