Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 734 insertions, 0 deletions

diff --git a/drivers/net/ppp/ppp_synctty.c b/drivers/net/ppp/ppp_synctty.c
new file mode 100644
index 000000000..18283b7b9
--- /dev/null
+++ b/drivers/net/ppp/ppp_synctty.c
@@ -0,0 +1,734 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * PPP synchronous tty channel driver for Linux.
+ *
+ * This is a ppp channel driver that can be used with tty device drivers
+ * that are frame oriented, such as synchronous HDLC devices.
+ *
+ * Complete PPP frames without encoding/decoding are exchanged between
+ * the channel driver and the device driver.
+ *
+ * The async map IOCTL codes are implemented to keep the user mode
+ * applications happy if they call them. Synchronous PPP does not use
+ * the async maps.
+ *
+ * Copyright 1999 Paul Mackerras.
+ *
+ * Also touched by the grubby hands of Paul Fulghum paulkf@microgate.com
+ *
+ * This driver provides the encapsulation and framing for sending
+ * and receiving PPP frames over sync serial lines.  It relies on
+ * the generic PPP layer to give it frames to send and to process
+ * received frames.  It implements the PPP line discipline.
+ *
+ * Part of the code in this driver was inspired by the old async-only
+ * PPP driver, written by Michael Callahan and Al Longyear, and
+ * subsequently hacked by Paul Mackerras.
+ *
+ * ==FILEVERSION 20040616==
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/skbuff.h>
+#include <linux/tty.h>
+#include <linux/netdevice.h>
+#include <linux/poll.h>
+#include <linux/ppp_defs.h>
+#include <linux/ppp-ioctl.h>
+#include <linux/ppp_channel.h>
+#include <linux/spinlock.h>
+#include <linux/completion.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/slab.h>
+#include <linux/refcount.h>
+#include <asm/unaligned.h>
+#include <linux/uaccess.h>
+
+#define PPP_VERSION	"2.4.2"
+
+/* Structure for storing local state. */
+struct syncppp {
+	struct tty_struct *tty;
+	unsigned int	flags;
+	unsigned int	rbits;
+	int		mru;
+	spinlock_t	xmit_lock;
+	spinlock_t	recv_lock;
+	unsigned long	xmit_flags;
+	u32		xaccm[8];
+	u32		raccm;
+	unsigned int	bytes_sent;
+	unsigned int	bytes_rcvd;
+
+	struct sk_buff	*tpkt;
+	unsigned long	last_xmit;
+
+	struct sk_buff_head rqueue;
+
+	struct tasklet_struct tsk;
+
+	refcount_t	refcnt;
+	struct completion dead_cmp;
+	struct ppp_channel chan;	/* interface to generic ppp layer */
+};
+
+/* Bit numbers in xmit_flags */
+#define XMIT_WAKEUP	0
+#define XMIT_FULL	1
+
+/* Bits in rbits */
+#define SC_RCV_BITS	(SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP)
+
+#define PPPSYNC_MAX_RQLEN	32	/* arbitrary */
+
+/*
+ * Prototypes.
+ */
+static struct sk_buff* ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *);
+static int ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb);
+static int ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd,
+			  unsigned long arg);
+static void ppp_sync_process(struct tasklet_struct *t);
+static int ppp_sync_push(struct syncppp *ap);
+static void ppp_sync_flush_output(struct syncppp *ap);
+static void ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
+			   const char *flags, int count);
+
+static const struct ppp_channel_ops sync_ops = {
+	.start_xmit = ppp_sync_send,
+	.ioctl      = ppp_sync_ioctl,
+};
+
+/*
+ * Utility procedure to print a buffer in hex/ascii
+ */
+static void
+ppp_print_buffer (const char *name, const __u8 *buf, int count)
+{
+	if (name != NULL)
+		printk(KERN_DEBUG "ppp_synctty: %s, count = %d\n", name, count);
+
+	print_hex_dump_bytes("", DUMP_PREFIX_NONE, buf, count);
+}
+
+
+/*
+ * Routines implementing the synchronous PPP line discipline.
+ */
+
+/*
+ * We have a potential race on dereferencing tty->disc_data,
+ * because the tty layer provides no locking at all - thus one
+ * cpu could be running ppp_synctty_receive while another
+ * calls ppp_synctty_close, which zeroes tty->disc_data and
+ * frees the memory that ppp_synctty_receive is using.  The best
+ * way to fix this is to use a rwlock in the tty struct, but for now
+ * we use a single global rwlock for all ttys in ppp line discipline.
+ *
+ * FIXME: Fixed in tty_io nowadays.
+ */
+static DEFINE_RWLOCK(disc_data_lock);
+
+static struct syncppp *sp_get(struct tty_struct *tty)
+{
+	struct syncppp *ap;
+
+	read_lock(&disc_data_lock);
+	ap = tty->disc_data;
+	if (ap != NULL)
+		refcount_inc(&ap->refcnt);
+	read_unlock(&disc_data_lock);
+	return ap;
+}
+
+static void sp_put(struct syncppp *ap)
+{
+	if (refcount_dec_and_test(&ap->refcnt))
+		complete(&ap->dead_cmp);
+}
+
+/*
+ * Called when a tty is put into sync-PPP line discipline.
+ */
+static int
+ppp_sync_open(struct tty_struct *tty)
+{
+	struct syncppp *ap;
+	int err;
+	int speed;
+
+	if (tty->ops->write == NULL)
+		return -EOPNOTSUPP;
+
+	ap = kzalloc(sizeof(*ap), GFP_KERNEL);
+	err = -ENOMEM;
+	if (!ap)
+		goto out;
+
+	/* initialize the syncppp structure */
+	ap->tty = tty;
+	ap->mru = PPP_MRU;
+	spin_lock_init(&ap->xmit_lock);
+	spin_lock_init(&ap->recv_lock);
+	ap->xaccm[0] = ~0U;
+	ap->xaccm[3] = 0x60000000U;
+	ap->raccm = ~0U;
+
+	skb_queue_head_init(&ap->rqueue);
+	tasklet_setup(&ap->tsk, ppp_sync_process);
+
+	refcount_set(&ap->refcnt, 1);
+	init_completion(&ap->dead_cmp);
+
+	ap->chan.private = ap;
+	ap->chan.ops = &sync_ops;
+	ap->chan.mtu = PPP_MRU;
+	ap->chan.hdrlen = 2;	/* for A/C bytes */
+	speed = tty_get_baud_rate(tty);
+	ap->chan.speed = speed;
+	err = ppp_register_channel(&ap->chan);
+	if (err)
+		goto out_free;
+
+	tty->disc_data = ap;
+	tty->receive_room = 65536;
+	return 0;
+
+ out_free:
+	kfree(ap);
+ out:
+	return err;
+}
+
+/*
+ * Called when the tty is put into another line discipline
+ * or it hangs up.  We have to wait for any cpu currently
+ * executing in any of the other ppp_synctty_* routines to
+ * finish before we can call ppp_unregister_channel and free
+ * the syncppp struct.  This routine must be called from
+ * process context, not interrupt or softirq context.
+ */
+static void
+ppp_sync_close(struct tty_struct *tty)
+{
+	struct syncppp *ap;
+
+	write_lock_irq(&disc_data_lock);
+	ap = tty->disc_data;
+	tty->disc_data = NULL;
+	write_unlock_irq(&disc_data_lock);
+	if (!ap)
+		return;
+
+	/*
+	 * We have now ensured that nobody can start using ap from now
+	 * on, but we have to wait for all existing users to finish.
+	 * Note that ppp_unregister_channel ensures that no calls to
+	 * our channel ops (i.e. ppp_sync_send/ioctl) are in progress
+	 * by the time it returns.
+	 */
+	if (!refcount_dec_and_test(&ap->refcnt))
+		wait_for_completion(&ap->dead_cmp);
+	tasklet_kill(&ap->tsk);
+
+	ppp_unregister_channel(&ap->chan);
+	skb_queue_purge(&ap->rqueue);
+	kfree_skb(ap->tpkt);
+	kfree(ap);
+}
+
+/*
+ * Called on tty hangup in process context.
+ *
+ * Wait for I/O to driver to complete and unregister PPP channel.
+ * This is already done by the close routine, so just call that.
+ */
+static void ppp_sync_hangup(struct tty_struct *tty)
+{
+	ppp_sync_close(tty);
+}
+
+/*
+ * Read does nothing - no data is ever available this way.
+ * Pppd reads and writes packets via /dev/ppp instead.
+ */
+static ssize_t
+ppp_sync_read(struct tty_struct *tty, struct file *file,
+	      unsigned char *buf, size_t count,
+	      void **cookie, unsigned long offset)
+{
+	return -EAGAIN;
+}
+
+/*
+ * Write on the tty does nothing, the packets all come in
+ * from the ppp generic stuff.
+ */
+static ssize_t
+ppp_sync_write(struct tty_struct *tty, struct file *file,
+		const unsigned char *buf, size_t count)
+{
+	return -EAGAIN;
+}
+
+static int
+ppp_synctty_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
+{
+	struct syncppp *ap = sp_get(tty);
+	int __user *p = (int __user *)arg;
+	int err, val;
+
+	if (!ap)
+		return -ENXIO;
+	err = -EFAULT;
+	switch (cmd) {
+	case PPPIOCGCHAN:
+		err = -EFAULT;
+		if (put_user(ppp_channel_index(&ap->chan), p))
+			break;
+		err = 0;
+		break;
+
+	case PPPIOCGUNIT:
+		err = -EFAULT;
+		if (put_user(ppp_unit_number(&ap->chan), p))
+			break;
+		err = 0;
+		break;
+
+	case TCFLSH:
+		/* flush our buffers and the serial port's buffer */
+		if (arg == TCIOFLUSH || arg == TCOFLUSH)
+			ppp_sync_flush_output(ap);
+		err = n_tty_ioctl_helper(tty, cmd, arg);
+		break;
+
+	case FIONREAD:
+		val = 0;
+		if (put_user(val, p))
+			break;
+		err = 0;
+		break;
+
+	default:
+		err = tty_mode_ioctl(tty, cmd, arg);
+		break;
+	}
+
+	sp_put(ap);
+	return err;
+}
+
+/* No kernel lock - fine */
+static __poll_t
+ppp_sync_poll(struct tty_struct *tty, struct file *file, poll_table *wait)
+{
+	return 0;
+}
+
+/* May sleep, don't call from interrupt level or with interrupts disabled */
+static void
+ppp_sync_receive(struct tty_struct *tty, const unsigned char *buf,
+		  const char *cflags, int count)
+{
+	struct syncppp *ap = sp_get(tty);
+	unsigned long flags;
+
+	if (!ap)
+		return;
+	spin_lock_irqsave(&ap->recv_lock, flags);
+	ppp_sync_input(ap, buf, cflags, count);
+	spin_unlock_irqrestore(&ap->recv_lock, flags);
+	if (!skb_queue_empty(&ap->rqueue))
+		tasklet_schedule(&ap->tsk);
+	sp_put(ap);
+	tty_unthrottle(tty);
+}
+
+static void
+ppp_sync_wakeup(struct tty_struct *tty)
+{
+	struct syncppp *ap = sp_get(tty);
+
+	clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+	if (!ap)
+		return;
+	set_bit(XMIT_WAKEUP, &ap->xmit_flags);
+	tasklet_schedule(&ap->tsk);
+	sp_put(ap);
+}
+
+
+static struct tty_ldisc_ops ppp_sync_ldisc = {
+	.owner	= THIS_MODULE,
+	.num	= N_SYNC_PPP,
+	.name	= "pppsync",
+	.open	= ppp_sync_open,
+	.close	= ppp_sync_close,
+	.hangup	= ppp_sync_hangup,
+	.read	= ppp_sync_read,
+	.write	= ppp_sync_write,
+	.ioctl	= ppp_synctty_ioctl,
+	.poll	= ppp_sync_poll,
+	.receive_buf = ppp_sync_receive,
+	.write_wakeup = ppp_sync_wakeup,
+};
+
+static int __init
+ppp_sync_init(void)
+{
+	int err;
+
+	err = tty_register_ldisc(&ppp_sync_ldisc);
+	if (err != 0)
+		printk(KERN_ERR "PPP_sync: error %d registering line disc.\n",
+		       err);
+	return err;
+}
+
+/*
+ * The following routines provide the PPP channel interface.
+ */
+static int
+ppp_sync_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg)
+{
+	struct syncppp *ap = chan->private;
+	int err, val;
+	u32 accm[8];
+	void __user *argp = (void __user *)arg;
+	u32 __user *p = argp;
+
+	err = -EFAULT;
+	switch (cmd) {
+	case PPPIOCGFLAGS:
+		val = ap->flags | ap->rbits;
+		if (put_user(val, (int __user *) argp))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSFLAGS:
+		if (get_user(val, (int __user *) argp))
+			break;
+		ap->flags = val & ~SC_RCV_BITS;
+		spin_lock_irq(&ap->recv_lock);
+		ap->rbits = val & SC_RCV_BITS;
+		spin_unlock_irq(&ap->recv_lock);
+		err = 0;
+		break;
+
+	case PPPIOCGASYNCMAP:
+		if (put_user(ap->xaccm[0], p))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSASYNCMAP:
+		if (get_user(ap->xaccm[0], p))
+			break;
+		err = 0;
+		break;
+
+	case PPPIOCGRASYNCMAP:
+		if (put_user(ap->raccm, p))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSRASYNCMAP:
+		if (get_user(ap->raccm, p))
+			break;
+		err = 0;
+		break;
+
+	case PPPIOCGXASYNCMAP:
+		if (copy_to_user(argp, ap->xaccm, sizeof(ap->xaccm)))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSXASYNCMAP:
+		if (copy_from_user(accm, argp, sizeof(accm)))
+			break;
+		accm[2] &= ~0x40000000U;	/* can't escape 0x5e */
+		accm[3] |= 0x60000000U;		/* must escape 0x7d, 0x7e */
+		memcpy(ap->xaccm, accm, sizeof(ap->xaccm));
+		err = 0;
+		break;
+
+	case PPPIOCGMRU:
+		if (put_user(ap->mru, (int __user *) argp))
+			break;
+		err = 0;
+		break;
+	case PPPIOCSMRU:
+		if (get_user(val, (int __user *) argp))
+			break;
+		if (val < PPP_MRU)
+			val = PPP_MRU;
+		ap->mru = val;
+		err = 0;
+		break;
+
+	default:
+		err = -ENOTTY;
+	}
+	return err;
+}
+
+/*
+ * This is called at softirq level to deliver received packets
+ * to the ppp_generic code, and to tell the ppp_generic code
+ * if we can accept more output now.
+ */
+static void ppp_sync_process(struct tasklet_struct *t)
+{
+	struct syncppp *ap = from_tasklet(ap, t, tsk);
+	struct sk_buff *skb;
+
+	/* process received packets */
+	while ((skb = skb_dequeue(&ap->rqueue)) != NULL) {
+		if (skb->len == 0) {
+			/* zero length buffers indicate error */
+			ppp_input_error(&ap->chan, 0);
+			kfree_skb(skb);
+		}
+		else
+			ppp_input(&ap->chan, skb);
+	}
+
+	/* try to push more stuff out */
+	if (test_bit(XMIT_WAKEUP, &ap->xmit_flags) && ppp_sync_push(ap))
+		ppp_output_wakeup(&ap->chan);
+}
+
+/*
+ * Procedures for encapsulation and framing.
+ */
+
+static struct sk_buff*
+ppp_sync_txmunge(struct syncppp *ap, struct sk_buff *skb)
+{
+	int proto;
+	unsigned char *data;
+	int islcp;
+
+	data  = skb->data;
+	proto = get_unaligned_be16(data);
+
+	/* LCP packets with codes between 1 (configure-request)
+	 * and 7 (code-reject) must be sent as though no options
+	 * have been negotiated.
+	 */
+	islcp = proto == PPP_LCP && 1 <= data[2] && data[2] <= 7;
+
+	/* compress protocol field if option enabled */
+	if (data[0] == 0 && (ap->flags & SC_COMP_PROT) && !islcp)
+		skb_pull(skb,1);
+
+	/* prepend address/control fields if necessary */
+	if ((ap->flags & SC_COMP_AC) == 0 || islcp) {
+		if (skb_headroom(skb) < 2) {
+			struct sk_buff *npkt = dev_alloc_skb(skb->len + 2);
+			if (npkt == NULL) {
+				kfree_skb(skb);
+				return NULL;
+			}
+			skb_reserve(npkt,2);
+			skb_copy_from_linear_data(skb,
+				      skb_put(npkt, skb->len), skb->len);
+			consume_skb(skb);
+			skb = npkt;
+		}
+		skb_push(skb,2);
+		skb->data[0] = PPP_ALLSTATIONS;
+		skb->data[1] = PPP_UI;
+	}
+
+	ap->last_xmit = jiffies;
+
+	if (skb && ap->flags & SC_LOG_OUTPKT)
+		ppp_print_buffer ("send buffer", skb->data, skb->len);
+
+	return skb;
+}
+
+/*
+ * Transmit-side routines.
+ */
+
+/*
+ * Send a packet to the peer over an sync tty line.
+ * Returns 1 iff the packet was accepted.
+ * If the packet was not accepted, we will call ppp_output_wakeup
+ * at some later time.
+ */
+static int
+ppp_sync_send(struct ppp_channel *chan, struct sk_buff *skb)
+{
+	struct syncppp *ap = chan->private;
+
+	ppp_sync_push(ap);
+
+	if (test_and_set_bit(XMIT_FULL, &ap->xmit_flags))
+		return 0;	/* already full */
+	skb = ppp_sync_txmunge(ap, skb);
+	if (skb != NULL)
+		ap->tpkt = skb;
+	else
+		clear_bit(XMIT_FULL, &ap->xmit_flags);
+
+	ppp_sync_push(ap);
+	return 1;
+}
+
+/*
+ * Push as much data as possible out to the tty.
+ */
+static int
+ppp_sync_push(struct syncppp *ap)
+{
+	int sent, done = 0;
+	struct tty_struct *tty = ap->tty;
+	int tty_stuffed = 0;
+
+	if (!spin_trylock_bh(&ap->xmit_lock))
+		return 0;
+	for (;;) {
+		if (test_and_clear_bit(XMIT_WAKEUP, &ap->xmit_flags))
+			tty_stuffed = 0;
+		if (!tty_stuffed && ap->tpkt) {
+			set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
+			sent = tty->ops->write(tty, ap->tpkt->data, ap->tpkt->len);
+			if (sent < 0)
+				goto flush;	/* error, e.g. loss of CD */
+			if (sent < ap->tpkt->len) {
+				tty_stuffed = 1;
+			} else {
+				consume_skb(ap->tpkt);
+				ap->tpkt = NULL;
+				clear_bit(XMIT_FULL, &ap->xmit_flags);
+				done = 1;
+			}
+			continue;
+		}
+		/* haven't made any progress */
+		spin_unlock_bh(&ap->xmit_lock);
+		if (!(test_bit(XMIT_WAKEUP, &ap->xmit_flags) ||
+		      (!tty_stuffed && ap->tpkt)))
+			break;
+		if (!spin_trylock_bh(&ap->xmit_lock))
+			break;
+	}
+	return done;
+
+flush:
+	if (ap->tpkt) {
+		kfree_skb(ap->tpkt);
+		ap->tpkt = NULL;
+		clear_bit(XMIT_FULL, &ap->xmit_flags);
+		done = 1;
+	}
+	spin_unlock_bh(&ap->xmit_lock);
+	return done;
+}
+
+/*
+ * Flush output from our internal buffers.
+ * Called for the TCFLSH ioctl.
+ */
+static void
+ppp_sync_flush_output(struct syncppp *ap)
+{
+	int done = 0;
+
+	spin_lock_bh(&ap->xmit_lock);
+	if (ap->tpkt != NULL) {
+		kfree_skb(ap->tpkt);
+		ap->tpkt = NULL;
+		clear_bit(XMIT_FULL, &ap->xmit_flags);
+		done = 1;
+	}
+	spin_unlock_bh(&ap->xmit_lock);
+	if (done)
+		ppp_output_wakeup(&ap->chan);
+}
+
+/*
+ * Receive-side routines.
+ */
+
+/* called when the tty driver has data for us.
+ *
+ * Data is frame oriented: each call to ppp_sync_input is considered
+ * a whole frame. If the 1st flag byte is non-zero then the whole
+ * frame is considered to be in error and is tossed.
+ */
+static void
+ppp_sync_input(struct syncppp *ap, const unsigned char *buf,
+		const char *flags, int count)
+{
+	struct sk_buff *skb;
+	unsigned char *p;
+
+	if (count == 0)
+		return;
+
+	if (ap->flags & SC_LOG_INPKT)
+		ppp_print_buffer ("receive buffer", buf, count);
+
+	/* stuff the chars in the skb */
+	skb = dev_alloc_skb(ap->mru + PPP_HDRLEN + 2);
+	if (!skb) {
+		printk(KERN_ERR "PPPsync: no memory (input pkt)\n");
+		goto err;
+	}
+	/* Try to get the payload 4-byte aligned */
+	if (buf[0] != PPP_ALLSTATIONS)
+		skb_reserve(skb, 2 + (buf[0] & 1));
+
+	if (flags && *flags) {
+		/* error flag set, ignore frame */
+		goto err;
+	} else if (count > skb_tailroom(skb)) {
+		/* packet overflowed MRU */
+		goto err;
+	}
+
+	skb_put_data(skb, buf, count);
+
+	/* strip address/control field if present */
+	p = skb->data;
+	if (p[0] == PPP_ALLSTATIONS && p[1] == PPP_UI) {
+		/* chop off address/control */
+		if (skb->len < 3)
+			goto err;
+		p = skb_pull(skb, 2);
+	}
+
+	/* PPP packet length should be >= 2 bytes when protocol field is not
+	 * compressed.
+	 */
+	if (!(p[0] & 0x01) && skb->len < 2)
+		goto err;
+
+	/* queue the frame to be processed */
+	skb_queue_tail(&ap->rqueue, skb);
+	return;
+
+err:
+	/* queue zero length packet as error indication */
+	if (skb || (skb = dev_alloc_skb(0))) {
+		skb_trim(skb, 0);
+		skb_queue_tail(&ap->rqueue, skb);
+	}
+}
+
+static void __exit
+ppp_sync_cleanup(void)
+{
+	tty_unregister_ldisc(&ppp_sync_ldisc);
+}
+
+module_init(ppp_sync_init);
+module_exit(ppp_sync_cleanup);
+MODULE_LICENSE("GPL");
+MODULE_ALIAS_LDISC(N_SYNC_PPP);