/*
 * 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.
 *
 * Copyright Jonathan Naylor G4KLX (g4klx@g4klx.demon.co.uk)
 * Copyright Darryl Miles G7LED (dlm@g7led.demon.co.uk)
 */
#include <linux/errno.h>
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/in.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/sockios.h>
#include <linux/net.h>
#include <linux/slab.h>
#include <net/ax25.h>
#include <linux/inet.h>
#include <linux/netdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/uaccess.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/interrupt.h>
#include <net/netrom.h>

/*
 *	This is where all NET/ROM frames pass, except for IP-over-NET/ROM which
 *	cannot be fragmented in this manner.
 */
void nr_output(struct sock *sk, struct sk_buff *skb)
{
	struct sk_buff *skbn;
	unsigned char transport[NR_TRANSPORT_LEN];
	int err, frontlen, len;

	if (skb->len - NR_TRANSPORT_LEN > NR_MAX_PACKET_SIZE) {
		/* Save a copy of the Transport Header */
		skb_copy_from_linear_data(skb, transport, NR_TRANSPORT_LEN);
		skb_pull(skb, NR_TRANSPORT_LEN);

		frontlen = skb_headroom(skb);

		while (skb->len > 0) {
			if ((skbn = sock_alloc_send_skb(sk, frontlen + NR_MAX_PACKET_SIZE, 0, &err)) == NULL)
				return;

			skb_reserve(skbn, frontlen);

			len = (NR_MAX_PACKET_SIZE > skb->len) ? skb->len : NR_MAX_PACKET_SIZE;

			/* Copy the user data */
			skb_copy_from_linear_data(skb, skb_put(skbn, len), len);
			skb_pull(skb, len);

			/* Duplicate the Transport Header */
			skb_push(skbn, NR_TRANSPORT_LEN);
			skb_copy_to_linear_data(skbn, transport,
						NR_TRANSPORT_LEN);
			if (skb->len > 0)
				skbn->data[4] |= NR_MORE_FLAG;

			skb_queue_tail(&sk->sk_write_queue, skbn); /* Throw it on the queue */
		}

		kfree_skb(skb);
	} else {
		skb_queue_tail(&sk->sk_write_queue, skb);		/* Throw it on the queue */
	}

	nr_kick(sk);
}

/*
 *	This procedure is passed a buffer descriptor for an iframe. It builds
 *	the rest of the control part of the frame and then writes it out.
 */
static void nr_send_iframe(struct sock *sk, struct sk_buff *skb)
{
	struct nr_sock *nr = nr_sk(sk);

	if (skb == NULL)
		return;

	skb->data[2] = nr->vs;
	skb->data[3] = nr->vr;

	if (nr->condition & NR_COND_OWN_RX_BUSY)
		skb->data[4] |= NR_CHOKE_FLAG;

	nr_start_idletimer(sk);

	nr_transmit_buffer(sk, skb);
}

void nr_send_nak_frame(struct sock *sk)
{
	struct sk_buff *skb, *skbn;
	struct nr_sock *nr = nr_sk(sk);

	if ((skb = skb_peek(&nr->ack_queue)) == NULL)
		return;

	if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL)
		return;

	skbn->data[2] = nr->va;
	skbn->data[3] = nr->vr;

	if (nr->condition & NR_COND_OWN_RX_BUSY)
		skbn->data[4] |= NR_CHOKE_FLAG;

	nr_transmit_buffer(sk, skbn);

	nr->condition &= ~NR_COND_ACK_PENDING;
	nr->vl         = nr->vr;

	nr_stop_t1timer(sk);
}

void nr_kick(struct sock *sk)
{
	struct nr_sock *nr = nr_sk(sk);
	struct sk_buff *skb, *skbn;
	unsigned short start, end;

	if (nr->state != NR_STATE_3)
		return;

	if (nr->condition & NR_COND_PEER_RX_BUSY)
		return;

	if (!skb_peek(&sk->sk_write_queue))
		return;

	start = (skb_peek(&nr->ack_queue) == NULL) ? nr->va : nr->vs;
	end   = (nr->va + nr->window) % NR_MODULUS;

	if (start == end)
		return;

	nr->vs = start;

	/*
	 * Transmit data until either we're out of data to send or
	 * the window is full.
	 */

	/*
	 * Dequeue the frame and copy it.
	 */
	skb = skb_dequeue(&sk->sk_write_queue);

	do {
		if ((skbn = skb_clone(skb, GFP_ATOMIC)) == NULL) {
			skb_queue_head(&sk->sk_write_queue, skb);
			break;
		}

		skb_set_owner_w(skbn, sk);

		/*
		 * Transmit the frame copy.
		 */
		nr_send_iframe(sk, skbn);

		nr->vs = (nr->vs + 1) % NR_MODULUS;

		/*
		 * Requeue the original data frame.
		 */
		skb_queue_tail(&nr->ack_queue, skb);

	} while (nr->vs != end &&
		 (skb = skb_dequeue(&sk->sk_write_queue)) != NULL);

	nr->vl         = nr->vr;
	nr->condition &= ~NR_COND_ACK_PENDING;

	if (!nr_t1timer_running(sk))
		nr_start_t1timer(sk);
}

void nr_transmit_buffer(struct sock *sk, struct sk_buff *skb)
{
	struct nr_sock *nr = nr_sk(sk);
	unsigned char *dptr;

	/*
	 *	Add the protocol byte and network header.
	 */
	dptr = skb_push(skb, NR_NETWORK_LEN);

	memcpy(dptr, &nr->source_addr, AX25_ADDR_LEN);
	dptr[6] &= ~AX25_CBIT;
	dptr[6] &= ~AX25_EBIT;
	dptr[6] |= AX25_SSSID_SPARE;
	dptr += AX25_ADDR_LEN;

	memcpy(dptr, &nr->dest_addr, AX25_ADDR_LEN);
	dptr[6] &= ~AX25_CBIT;
	dptr[6] |= AX25_EBIT;
	dptr[6] |= AX25_SSSID_SPARE;
	dptr += AX25_ADDR_LEN;

	*dptr++ = sysctl_netrom_network_ttl_initialiser;

	if (!nr_route_frame(skb, NULL)) {
		kfree_skb(skb);
		nr_disconnect(sk, ENETUNREACH);
	}
}

/*
 * The following routines are taken from page 170 of the 7th ARRL Computer
 * Networking Conference paper, as is the whole state machine.
 */

void nr_establish_data_link(struct sock *sk)
{
	struct nr_sock *nr = nr_sk(sk);

	nr->condition = 0x00;
	nr->n2count   = 0;

	nr_write_internal(sk, NR_CONNREQ);

	nr_stop_t2timer(sk);
	nr_stop_t4timer(sk);
	nr_stop_idletimer(sk);
	nr_start_t1timer(sk);
}

/*
 * Never send a NAK when we are CHOKEd.
 */
void nr_enquiry_response(struct sock *sk)
{
	struct nr_sock *nr = nr_sk(sk);
	int frametype = NR_INFOACK;

	if (nr->condition & NR_COND_OWN_RX_BUSY) {
		frametype |= NR_CHOKE_FLAG;
	} else {
		if (skb_peek(&nr->reseq_queue) != NULL)
			frametype |= NR_NAK_FLAG;
	}

	nr_write_internal(sk, frametype);

	nr->vl         = nr->vr;
	nr->condition &= ~NR_COND_ACK_PENDING;
}

void nr_check_iframes_acked(struct sock *sk, unsigned short nr)
{
	struct nr_sock *nrom = nr_sk(sk);

	if (nrom->vs == nr) {
		nr_frames_acked(sk, nr);
		nr_stop_t1timer(sk);
		nrom->n2count = 0;
	} else {
		if (nrom->va != nr) {
			nr_frames_acked(sk, nr);
			nr_start_t1timer(sk);
		}
	}
}
ay erroneously enable an
energy-efficiency setting -- MSR_IA32_POWER_CTL BIT-EE, which is not
recommended to be enabled on this SKU.

On the failing systems, this BIOS issue was not discovered when the
desktop motherboard was tested with Windows, because the BIOS also
neglects to provide the ACPI/CPPC table, that Windows requires to enable
HWP, and so Windows runs in legacy P-state mode, where this setting has
no effect.

Linux' intel_pstate driver does not require ACPI/CPPC to enable HWP, and
so it runs in HWP mode, exposing this incorrect BIOS configuration.

There are several ways to address this problem.

First, Linux can also run in legacy P-state mode on this system.
As intel_pstate is how Linux enables HWP, booting with
"intel_pstate=disable"
will run in acpi-cpufreq/ondemand legacy p-state mode.

Or second, the "performance" governor can be used with intel_pstate,
which will modify HWP.EPP to 0.

Or third, starting in 4.10, the
/sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference
attribute in can be updated from "balance_power" to "performance".

Or fourth, apply this patch, which fixes the erroneous setting of
MSR_IA32_POWER_CTL BIT_EE on this model, allowing the default
configuration to function as designed.

Signed-off-by: Srinivas Pandruvada &lt;srinivas.pandruvada@linux.intel.com&gt;
Reviewed-by: Len Brown &lt;len.brown@intel.com&gt;
Cc: 4.6+ &lt;stable@vger.kernel.org&gt; # 4.6+
Signed-off-by: Rafael J. Wysocki &lt;rafael.j.wysocki@intel.com&gt;
</div><div class='diffstat-header'><a href='/cgit.cgi/linux/net-next.git/diff/?id=6e978b22efa1db9f6e71b24440b5f1d93e968ee3'>Diffstat</a> (limited to 'net/802')</div><table summary='diffstat' class='diffstat'>