/* * PPP async serial channel driver for Linux. * * Copyright 1999 Paul Mackerras. * * 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. * * This driver provides the encapsulation and framing for sending * and receiving PPP frames over async 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. */ #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/crc-ccitt.h>#include <linux/ppp_defs.h>#include <linux/if_ppp.h>#include <linux/ppp_channel.h>#include <linux/spinlock.h>#include <linux/init.h>#include <linux/jiffies.h>#include <asm/uaccess.h>#include <asm/string.h> #define PPP_VERSION "2.4.2" #define OBUFSIZE 256 /* Structure for storing local state. */struct asyncppp { struct tty_struct *tty; unsigned int flags; unsigned int state; 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; int tpkt_pos; u16 tfcs; unsigned char *optr; unsigned char *olim; unsigned long last_xmit; struct sk_buff *rpkt; int lcp_fcs; struct sk_buff_head rqueue; struct tasklet_struct tsk; atomic_t refcnt; struct semaphore dead_sem; struct ppp_channel chan; /* interface to generic ppp layer */ unsigned char obuf[OBUFSIZE];}; /* Bit numbers in xmit_flags */#define XMIT_WAKEUP 0#define XMIT_FULL 1#define XMIT_BUSY 2 /* State bits */#define SC_TOSS 1#define SC_ESCAPE 2#define SC_PREV_ERROR 4 /* Bits in rbits */#define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP) static int flag_time = HZ;module_param(flag_time, int, 0);MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)");MODULE_LICENSE("GPL");MODULE_ALIAS_LDISC(N_PPP); /* * Prototypes. */static int ppp_async_encode(struct asyncppp *ap);static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb);static int ppp_async_push(struct asyncppp *ap);static void ppp_async_flush_output(struct asyncppp *ap);static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf, char *flags, int count);static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg);static void ppp_async_process(unsigned long arg); static void async_lcp_peek(struct asyncppp *ap, unsigned char *data, int len, int inbound); static struct ppp_channel_ops async_ops = { ppp_async_send, ppp_async_ioctl}; /* * Routines implementing the 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_asynctty_receive while another * calls ppp_asynctty_close, which zeroes tty->disc_data and * frees the memory that ppp_asynctty_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: this is no longer true. The _close path for the ldisc is * now guaranteed to be sane. */static DEFINE_RWLOCK(disc_data_lock); static struct asyncppp *ap_get(struct tty_struct *tty){ struct asyncppp *ap; read_lock(&disc_data_lock); ap = tty->disc_data; if (ap != NULL) atomic_inc(&ap->refcnt); read_unlock(&disc_data_lock); return ap;} static void ap_put(struct asyncppp *ap){ if (atomic_dec_and_test(&ap->refcnt)) up(&ap->dead_sem);} /* * Called when a tty is put into PPP line discipline. Called in process * context. */static intppp_asynctty_open(struct tty_struct *tty){ struct asyncppp *ap; int err; err = -ENOMEM; ap = kmalloc(sizeof(*ap), GFP_KERNEL); if (ap == 0) goto out; /* initialize the asyncppp structure */ memset(ap, 0, sizeof(*ap)); 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; ap->optr = ap->obuf; ap->olim = ap->obuf; ap->lcp_fcs = -1; skb_queue_head_init(&ap->rqueue); tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap); atomic_set(&ap->refcnt, 1); init_MUTEX_LOCKED(&ap->dead_sem); ap->chan.private = ap; ap->chan.ops = &async_ops; ap->chan.mtu = PPP_MRU; 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_asynctty_* routines to * finish before we can call ppp_unregister_channel and free * the asyncppp struct. This routine must be called from * process context, not interrupt or softirq context. */static voidppp_asynctty_close(struct tty_struct *tty){ struct asyncppp *ap; write_lock_irq(&disc_data_lock); ap = tty->disc_data; tty->disc_data = NULL; write_unlock_irq(&disc_data_lock); if (ap == 0) 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_async_send/ioctl) are in progress * by the time it returns. */ if (!atomic_dec_and_test(&ap->refcnt)) down(&ap->dead_sem); tasklet_kill(&ap->tsk); ppp_unregister_channel(&ap->chan); if (ap->rpkt != 0) kfree_skb(ap->rpkt); skb_queue_purge(&ap->rqueue); if (ap->tpkt != 0) 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 int ppp_asynctty_hangup(struct tty_struct *tty){ ppp_asynctty_close(tty); return 0;} /* * Read does nothing - no data is ever available this way. * Pppd reads and writes packets via /dev/ppp instead. */static ssize_tppp_asynctty_read(struct tty_struct *tty, struct file *file, unsigned char __user *buf, size_t count){ return -EAGAIN;} /* * Write on the tty does nothing, the packets all come in * from the ppp generic stuff. */static ssize_tppp_asynctty_write(struct tty_struct *tty, struct file *file, const unsigned char *buf, size_t count){ return -EAGAIN;} /* * Called in process context only. May be re-entered by multiple * ioctl calling threads. */ static intppp_asynctty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg){ struct asyncppp *ap = ap_get(tty); int err, val; int __user *p = (int __user *)arg; if (ap == 0) return -ENXIO; err = -EFAULT; switch (cmd) { case PPPIOCGCHAN: err = -ENXIO; if (ap == 0) break; err = -EFAULT; if (put_user(ppp_channel_index(&ap->chan), p)) break; err = 0; break; case PPPIOCGUNIT: err = -ENXIO; if (ap == 0) break; err = -EFAULT; if (put_user(ppp_unit_number(&ap->chan), p)) break; err = 0; break; case TCGETS: case TCGETA: err = n_tty_ioctl(tty, file, cmd, arg); break; case TCFLSH: /* flush our buffers and the serial port's buffer */ if (arg == TCIOFLUSH || arg == TCOFLUSH) ppp_async_flush_output(ap); err = n_tty_ioctl(tty, file, cmd, arg); break; case FIONREAD: val = 0; if (put_user(val, p)) break; err = 0; break; default: err = -ENOIOCTLCMD; } ap_put(ap); return err;} /* No kernel lock - fine */static unsigned intppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait){ return 0;} /* * This can now be called from hard interrupt level as well * as soft interrupt level or mainline. */static voidppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf, char *cflags, int count){ struct asyncppp *ap = ap_get(tty); unsigned long flags; if (ap == 0) return; spin_lock_irqsave(&ap->recv_lock, flags); ppp_async_input(ap, buf, cflags, count); spin_unlock_irqrestore(&ap->recv_lock, flags); if (!skb_queue_empty(&ap->rqueue)) tasklet_schedule(&ap->tsk); ap_put(ap); if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) && tty->driver->unthrottle) tty->driver->unthrottle(tty);} static voidppp_asynctty_wakeup(struct tty_struct *tty){ struct asyncppp *ap = ap_get(tty); clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); if (ap == 0) return; set_bit(XMIT_WAKEUP, &ap->xmit_flags); tasklet_schedule(&ap->tsk); ap_put(ap);} static struct tty_ldisc ppp_ldisc = { .owner = THIS_MODULE, .magic = TTY_LDISC_MAGIC, .name = "ppp", .open = ppp_asynctty_open, .close = ppp_asynctty_close, .hangup = ppp_asynctty_hangup, .read = ppp_asynctty_read, .write = ppp_asynctty_write, .ioctl = ppp_asynctty_ioctl, .poll = ppp_asynctty_poll, .receive_buf = ppp_asynctty_receive, .write_wakeup = ppp_asynctty_wakeup,}; static int __initppp_async_init(void){ int err; err = tty_register_ldisc(N_PPP, &ppp_ldisc); if (err != 0) printk(KERN_ERR "PPP_async: error %d registering line disc.\n", err); return err;} /* * The following routines provide the PPP channel interface. */static intppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg){ struct asyncppp *ap = chan->private; void __user *argp = (void __user *)arg; int __user *p = argp; int err, val; u32 accm[8]; err = -EFAULT; switch (cmd) { case PPPIOCGFLAGS: val = ap->flags | ap->rbits; if (put_user(val, p)) break; err = 0; break; case PPPIOCSFLAGS: if (get_user(val, p)) 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], (u32 __user *)argp)) break; err = 0; break; case PPPIOCSASYNCMAP: if (get_user(ap->xaccm[0], (u32 __user *)argp)) break; err = 0; break; case PPPIOCGRASYNCMAP: if (put_user(ap->raccm, (u32 __user *)argp)) break; err = 0; break; case PPPIOCSRASYNCMAP: if (get_user(ap->raccm, (u32 __user *)argp)) 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, p)) break; err = 0; break; case PPPIOCSMRU: if (get_user(val, p)) 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 packetsLines 1–500 of 1038. 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/* * PPP async serial channel driver for Linux. * * Copyright 1999 Paul Mackerras. * * 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. * * This driver provides the encapsulation and framing for sending * and receiving PPP frames over async 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. */ #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/crc-ccitt.h> #include <linux/ppp_defs.h> #include <linux/if_ppp.h> #include <linux/ppp_channel.h> #include <linux/spinlock.h> #include <linux/init.h> #include <linux/jiffies.h> #include <asm/uaccess.h> #include <asm/string.h> #define PPP_VERSION "2.4.2" #define OBUFSIZE 256 /* Structure for storing local state. */ struct asyncppp { struct tty_struct *tty; unsigned int flags; unsigned int state; 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; int tpkt_pos; u16 tfcs; unsigned char *optr; unsigned char *olim; unsigned long last_xmit; struct sk_buff *rpkt; int lcp_fcs; struct sk_buff_head rqueue; struct tasklet_struct tsk; atomic_t refcnt; struct semaphore dead_sem; struct ppp_channel chan; /* interface to generic ppp layer */ unsigned char obuf[OBUFSIZE]; }; /* Bit numbers in xmit_flags */ #define XMIT_WAKEUP 0 #define XMIT_FULL 1 #define XMIT_BUSY 2 /* State bits */ #define SC_TOSS 1 #define SC_ESCAPE 2 #define SC_PREV_ERROR 4 /* Bits in rbits */ #define SC_RCV_BITS (SC_RCV_B7_1|SC_RCV_B7_0|SC_RCV_ODDP|SC_RCV_EVNP) static int flag_time = HZ; module_param(flag_time, int, 0); MODULE_PARM_DESC(flag_time, "ppp_async: interval between flagged packets (in clock ticks)"); MODULE_LICENSE("GPL"); MODULE_ALIAS_LDISC(N_PPP); /* * Prototypes. */ static int ppp_async_encode(struct asyncppp *ap); static int ppp_async_send(struct ppp_channel *chan, struct sk_buff *skb); static int ppp_async_push(struct asyncppp *ap); static void ppp_async_flush_output(struct asyncppp *ap); static void ppp_async_input(struct asyncppp *ap, const unsigned char *buf, char *flags, int count); static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg); static void ppp_async_process(unsigned long arg); static void async_lcp_peek(struct asyncppp *ap, unsigned char *data, int len, int inbound); static struct ppp_channel_ops async_ops = { ppp_async_send, ppp_async_ioctl }; /* * Routines implementing the 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_asynctty_receive while another * calls ppp_asynctty_close, which zeroes tty->disc_data and * frees the memory that ppp_asynctty_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: this is no longer true. The _close path for the ldisc is * now guaranteed to be sane. */ static DEFINE_RWLOCK(disc_data_lock); static struct asyncppp *ap_get(struct tty_struct *tty) { struct asyncppp *ap; read_lock(&disc_data_lock); ap = tty->disc_data; if (ap != NULL) atomic_inc(&ap->refcnt); read_unlock(&disc_data_lock); return ap; } static void ap_put(struct asyncppp *ap) { if (atomic_dec_and_test(&ap->refcnt)) up(&ap->dead_sem); } /* * Called when a tty is put into PPP line discipline. Called in process * context. */ static int ppp_asynctty_open(struct tty_struct *tty) { struct asyncppp *ap; int err; err = -ENOMEM; ap = kmalloc(sizeof(*ap), GFP_KERNEL); if (ap == 0) goto out; /* initialize the asyncppp structure */ memset(ap, 0, sizeof(*ap)); 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; ap->optr = ap->obuf; ap->olim = ap->obuf; ap->lcp_fcs = -1; skb_queue_head_init(&ap->rqueue); tasklet_init(&ap->tsk, ppp_async_process, (unsigned long) ap); atomic_set(&ap->refcnt, 1); init_MUTEX_LOCKED(&ap->dead_sem); ap->chan.private = ap; ap->chan.ops = &async_ops; ap->chan.mtu = PPP_MRU; 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_asynctty_* routines to * finish before we can call ppp_unregister_channel and free * the asyncppp struct. This routine must be called from * process context, not interrupt or softirq context. */ static void ppp_asynctty_close(struct tty_struct *tty) { struct asyncppp *ap; write_lock_irq(&disc_data_lock); ap = tty->disc_data; tty->disc_data = NULL; write_unlock_irq(&disc_data_lock); if (ap == 0) 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_async_send/ioctl) are in progress * by the time it returns. */ if (!atomic_dec_and_test(&ap->refcnt)) down(&ap->dead_sem); tasklet_kill(&ap->tsk); ppp_unregister_channel(&ap->chan); if (ap->rpkt != 0) kfree_skb(ap->rpkt); skb_queue_purge(&ap->rqueue); if (ap->tpkt != 0) 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 int ppp_asynctty_hangup(struct tty_struct *tty) { ppp_asynctty_close(tty); return 0; } /* * Read does nothing - no data is ever available this way. * Pppd reads and writes packets via /dev/ppp instead. */ static ssize_t ppp_asynctty_read(struct tty_struct *tty, struct file *file, unsigned char __user *buf, size_t count) { return -EAGAIN; } /* * Write on the tty does nothing, the packets all come in * from the ppp generic stuff. */ static ssize_t ppp_asynctty_write(struct tty_struct *tty, struct file *file, const unsigned char *buf, size_t count) { return -EAGAIN; } /* * Called in process context only. May be re-entered by multiple * ioctl calling threads. */ static int ppp_asynctty_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg) { struct asyncppp *ap = ap_get(tty); int err, val; int __user *p = (int __user *)arg; if (ap == 0) return -ENXIO; err = -EFAULT; switch (cmd) { case PPPIOCGCHAN: err = -ENXIO; if (ap == 0) break; err = -EFAULT; if (put_user(ppp_channel_index(&ap->chan), p)) break; err = 0; break; case PPPIOCGUNIT: err = -ENXIO; if (ap == 0) break; err = -EFAULT; if (put_user(ppp_unit_number(&ap->chan), p)) break; err = 0; break; case TCGETS: case TCGETA: err = n_tty_ioctl(tty, file, cmd, arg); break; case TCFLSH: /* flush our buffers and the serial port's buffer */ if (arg == TCIOFLUSH || arg == TCOFLUSH) ppp_async_flush_output(ap); err = n_tty_ioctl(tty, file, cmd, arg); break; case FIONREAD: val = 0; if (put_user(val, p)) break; err = 0; break; default: err = -ENOIOCTLCMD; } ap_put(ap); return err; } /* No kernel lock - fine */ static unsigned int ppp_asynctty_poll(struct tty_struct *tty, struct file *file, poll_table *wait) { return 0; } /* * This can now be called from hard interrupt level as well * as soft interrupt level or mainline. */ static void ppp_asynctty_receive(struct tty_struct *tty, const unsigned char *buf, char *cflags, int count) { struct asyncppp *ap = ap_get(tty); unsigned long flags; if (ap == 0) return; spin_lock_irqsave(&ap->recv_lock, flags); ppp_async_input(ap, buf, cflags, count); spin_unlock_irqrestore(&ap->recv_lock, flags); if (!skb_queue_empty(&ap->rqueue)) tasklet_schedule(&ap->tsk); ap_put(ap); if (test_and_clear_bit(TTY_THROTTLED, &tty->flags) && tty->driver->unthrottle) tty->driver->unthrottle(tty); } static void ppp_asynctty_wakeup(struct tty_struct *tty) { struct asyncppp *ap = ap_get(tty); clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); if (ap == 0) return; set_bit(XMIT_WAKEUP, &ap->xmit_flags); tasklet_schedule(&ap->tsk); ap_put(ap); } static struct tty_ldisc ppp_ldisc = { .owner = THIS_MODULE, .magic = TTY_LDISC_MAGIC, .name = "ppp", .open = ppp_asynctty_open, .close = ppp_asynctty_close, .hangup = ppp_asynctty_hangup, .read = ppp_asynctty_read, .write = ppp_asynctty_write, .ioctl = ppp_asynctty_ioctl, .poll = ppp_asynctty_poll, .receive_buf = ppp_asynctty_receive, .write_wakeup = ppp_asynctty_wakeup, }; static int __init ppp_async_init(void) { int err; err = tty_register_ldisc(N_PPP, &ppp_ldisc); if (err != 0) printk(KERN_ERR "PPP_async: error %d registering line disc.\n", err); return err; } /* * The following routines provide the PPP channel interface. */ static int ppp_async_ioctl(struct ppp_channel *chan, unsigned int cmd, unsigned long arg) { struct asyncppp *ap = chan->private; void __user *argp = (void __user *)arg; int __user *p = argp; int err, val; u32 accm[8]; err = -EFAULT; switch (cmd) { case PPPIOCGFLAGS: val = ap->flags | ap->rbits; if (put_user(val, p)) break; err = 0; break; case PPPIOCSFLAGS: if (get_user(val, p)) 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], (u32 __user *)argp)) break; err = 0; break; case PPPIOCSASYNCMAP: if (get_user(ap->xaccm[0], (u32 __user *)argp)) break; err = 0; break; case PPPIOCGRASYNCMAP: if (put_user(ap->raccm, (u32 __user *)argp)) break; err = 0; break; case PPPIOCSRASYNCMAP: if (get_user(ap->raccm, (u32 __user *)argp)) 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, p)) break; err = 0; break; case PPPIOCSMRU: if (get_user(val, p)) 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