diff --git a/drivers/net/can/slcan/slcan-core.c b/drivers/net/can/slcan/slcan-core.c index 3394d059fc29..92cab093453d 100644 --- a/drivers/net/can/slcan/slcan-core.c +++ b/drivers/net/can/slcan/slcan-core.c @@ -1,11 +1,14 @@ /* * slcan.c - serial line CAN interface driver (using tty line discipline) * - * This file is derived from linux/drivers/net/slip/slip.c + * This file is derived from linux/drivers/net/slip/slip.c and got + * inspiration from linux/drivers/net/can/can327.c for the rework made + * on the line discipline code. * * slip.c Authors : Laurence Culhane * Fred N. van Kempen * slcan.c Author : Oliver Hartkopp + * can327.c Author : Max Staudt * * 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 @@ -46,15 +49,6 @@ MODULE_DESCRIPTION("serial line CAN interface"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Oliver Hartkopp "); -#define SLCAN_MAGIC 0x53CA - -static int maxdev = 10; /* MAX number of SLCAN channels; - * This can be overridden with - * insmod slcan.ko maxdev=nnn - */ -module_param(maxdev, int, 0); -MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); - /* maximum rx buffer len: extended CAN frame with timestamp */ #define SLC_MTU (sizeof("T1111222281122334455667788EA5F\r") + 1) @@ -68,7 +62,6 @@ MODULE_PARM_DESC(maxdev, "Maximum number of slcan interfaces"); SLC_STATE_BE_TXCNT_LEN) struct slcan { struct can_priv can; - int magic; /* Various fields. */ struct tty_struct *tty; /* ptr to TTY structure */ @@ -84,17 +77,14 @@ struct slcan { int xleft; /* bytes left in XMIT queue */ unsigned long flags; /* Flag values/ mode etc */ -#define SLF_INUSE 0 /* Channel in use */ -#define SLF_ERROR 1 /* Parity, etc. error */ -#define SLF_XCMD 2 /* Command transmission */ +#define SLF_ERROR 0 /* Parity, etc. error */ +#define SLF_XCMD 1 /* Command transmission */ unsigned long cmd_flags; /* Command flags */ #define CF_ERR_RST 0 /* Reset errors on open */ wait_queue_head_t xcmd_wait; /* Wait queue for commands */ /* transmission */ }; -static struct net_device **slcan_devs; - static const u32 slcan_bitrate_const[] = { 10000, 20000, 50000, 100000, 125000, 250000, 500000, 800000, 1000000 @@ -538,9 +528,8 @@ static void slcan_transmit(struct work_struct *work) spin_lock_bh(&sl->lock); /* First make sure we're connected. */ - if (!sl->tty || sl->magic != SLCAN_MAGIC || - (unlikely(!netif_running(sl->dev)) && - likely(!test_bit(SLF_XCMD, &sl->flags)))) { + if (unlikely(!netif_running(sl->dev)) && + likely(!test_bit(SLF_XCMD, &sl->flags))) { spin_unlock_bh(&sl->lock); return; } @@ -575,13 +564,9 @@ static void slcan_transmit(struct work_struct *work) */ static void slcan_write_wakeup(struct tty_struct *tty) { - struct slcan *sl; + struct slcan *sl = (struct slcan *)tty->disc_data; - rcu_read_lock(); - sl = rcu_dereference(tty->disc_data); - if (sl) - schedule_work(&sl->tx_work); - rcu_read_unlock(); + schedule_work(&sl->tx_work); } /* Send a can_frame to a TTY queue. */ @@ -652,25 +637,21 @@ static int slc_close(struct net_device *dev) struct slcan *sl = netdev_priv(dev); int err; - spin_lock_bh(&sl->lock); - if (sl->tty) { - if (sl->can.bittiming.bitrate && - sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { - spin_unlock_bh(&sl->lock); - err = slcan_transmit_cmd(sl, "C\r"); - spin_lock_bh(&sl->lock); - if (err) - netdev_warn(dev, - "failed to send close command 'C\\r'\n"); - } - - /* TTY discipline is running. */ - clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); + if (sl->can.bittiming.bitrate && + sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { + err = slcan_transmit_cmd(sl, "C\r"); + if (err) + netdev_warn(dev, + "failed to send close command 'C\\r'\n"); } + + /* TTY discipline is running. */ + clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags); + flush_work(&sl->tx_work); + netif_stop_queue(dev); sl->rcount = 0; sl->xleft = 0; - spin_unlock_bh(&sl->lock); close_candev(dev); sl->can.state = CAN_STATE_STOPPED; if (sl->can.bittiming.bitrate == CAN_BITRATE_UNKNOWN) @@ -686,9 +667,6 @@ static int slc_open(struct net_device *dev) unsigned char cmd[SLC_MTU]; int err, s; - if (!sl->tty) - return -ENODEV; - /* The baud rate is not set with the command * `ip link set type can bitrate ' and therefore * can.bittiming.bitrate is CAN_BITRATE_UNSET (0), causing @@ -703,8 +681,6 @@ static int slc_open(struct net_device *dev) return err; } - sl->flags &= BIT(SLF_INUSE); - if (sl->can.bittiming.bitrate != CAN_BITRATE_UNKNOWN) { for (s = 0; s < ARRAY_SIZE(slcan_bitrate_const); s++) { if (sl->can.bittiming.bitrate == slcan_bitrate_const[s]) @@ -748,14 +724,6 @@ static int slc_open(struct net_device *dev) return err; } -static void slc_dealloc(struct slcan *sl) -{ - int i = sl->dev->base_addr; - - free_candev(sl->dev); - slcan_devs[i] = NULL; -} - static int slcan_change_mtu(struct net_device *dev, int new_mtu) { return -EINVAL; @@ -785,7 +753,7 @@ static void slcan_receive_buf(struct tty_struct *tty, { struct slcan *sl = (struct slcan *)tty->disc_data; - if (!sl || sl->magic != SLCAN_MAGIC || !netif_running(sl->dev)) + if (!netif_running(sl->dev)) return; /* Read the characters out of the buffer */ @@ -800,80 +768,15 @@ static void slcan_receive_buf(struct tty_struct *tty, } } -/************************************ - * slcan_open helper routines. - ************************************/ - -/* Collect hanged up channels */ -static void slc_sync(void) -{ - int i; - struct net_device *dev; - struct slcan *sl; - - for (i = 0; i < maxdev; i++) { - dev = slcan_devs[i]; - if (!dev) - break; - - sl = netdev_priv(dev); - if (sl->tty) - continue; - if (dev->flags & IFF_UP) - dev_close(dev); - } -} - -/* Find a free SLCAN channel, and link in this `tty' line. */ -static struct slcan *slc_alloc(void) -{ - int i; - struct net_device *dev = NULL; - struct slcan *sl; - - for (i = 0; i < maxdev; i++) { - dev = slcan_devs[i]; - if (!dev) - break; - } - - /* Sorry, too many, all slots in use */ - if (i >= maxdev) - return NULL; - - dev = alloc_candev(sizeof(*sl), 1); - if (!dev) - return NULL; - - snprintf(dev->name, sizeof(dev->name), "slcan%d", i); - dev->netdev_ops = &slc_netdev_ops; - dev->base_addr = i; - slcan_set_ethtool_ops(dev); - sl = netdev_priv(dev); - - /* Initialize channel control data */ - sl->magic = SLCAN_MAGIC; - sl->dev = dev; - sl->can.bitrate_const = slcan_bitrate_const; - sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const); - spin_lock_init(&sl->lock); - INIT_WORK(&sl->tx_work, slcan_transmit); - init_waitqueue_head(&sl->xcmd_wait); - slcan_devs[i] = dev; - - return sl; -} - /* Open the high-level part of the SLCAN channel. * This function is called by the TTY module when the - * SLCAN line discipline is called for. Because we are - * sure the tty line exists, we only have to link it to - * a free SLCAN channel... + * SLCAN line discipline is called for. * * Called in process context serialized from other ldisc calls. */ static int slcan_open(struct tty_struct *tty) { + struct net_device *dev; struct slcan *sl; int err; @@ -883,72 +786,50 @@ static int slcan_open(struct tty_struct *tty) if (!tty->ops->write) return -EOPNOTSUPP; - /* RTnetlink lock is misused here to serialize concurrent - * opens of slcan channels. There are better ways, but it is - * the simplest one. - */ - rtnl_lock(); + dev = alloc_candev(sizeof(*sl), 1); + if (!dev) + return -ENFILE; - /* Collect hanged up channels. */ - slc_sync(); + sl = netdev_priv(dev); - sl = tty->disc_data; + /* Configure TTY interface */ + tty->receive_room = 65536; /* We don't flow control */ + sl->rcount = 0; + sl->xleft = 0; + spin_lock_init(&sl->lock); + INIT_WORK(&sl->tx_work, slcan_transmit); + init_waitqueue_head(&sl->xcmd_wait); - err = -EEXIST; - /* First make sure we're not already connected. */ - if (sl && sl->magic == SLCAN_MAGIC) - goto err_exit; + /* Configure CAN metadata */ + sl->can.bitrate_const = slcan_bitrate_const; + sl->can.bitrate_const_cnt = ARRAY_SIZE(slcan_bitrate_const); - /* OK. Find a free SLCAN channel to use. */ - err = -ENFILE; - sl = slc_alloc(); - if (!sl) - goto err_exit; + /* Configure netdev interface */ + sl->dev = dev; + strscpy(dev->name, "slcan%d", sizeof(dev->name)); + dev->netdev_ops = &slc_netdev_ops; + slcan_set_ethtool_ops(dev); + /* Mark ldisc channel as alive */ sl->tty = tty; tty->disc_data = sl; - if (!test_bit(SLF_INUSE, &sl->flags)) { - /* Perform the low-level SLCAN initialization. */ - sl->rcount = 0; - sl->xleft = 0; - - set_bit(SLF_INUSE, &sl->flags); - - rtnl_unlock(); - err = register_candev(sl->dev); - if (err) { - pr_err("slcan: can't register candev\n"); - goto err_free_chan; - } - } else { - rtnl_unlock(); + err = register_candev(dev); + if (err) { + free_candev(dev); + pr_err("slcan: can't register candev\n"); + return err; } - tty->receive_room = 65536; /* We don't flow control */ - + netdev_info(dev, "slcan on %s.\n", tty->name); /* TTY layer expects 0 on success */ return 0; - -err_free_chan: - rtnl_lock(); - sl->tty = NULL; - tty->disc_data = NULL; - clear_bit(SLF_INUSE, &sl->flags); - slc_dealloc(sl); - rtnl_unlock(); - return err; - -err_exit: - rtnl_unlock(); - - /* Count references from TTY module */ - return err; } /* Close down a SLCAN channel. * This means flushing out any pending queues, and then returning. This * call is serialized against other ldisc functions. + * Once this is called, no other ldisc function of ours is entered. * * We also use this method for a hangup event. */ @@ -956,28 +837,20 @@ static void slcan_close(struct tty_struct *tty) { struct slcan *sl = (struct slcan *)tty->disc_data; - /* First make sure we're connected. */ - if (!sl || sl->magic != SLCAN_MAGIC || sl->tty != tty) - return; + /* unregister_netdev() calls .ndo_stop() so we don't have to. + * Our .ndo_stop() also flushes the TTY write wakeup handler, + * so we can safely set sl->tty = NULL after this. + */ + unregister_candev(sl->dev); + /* Mark channel as dead */ spin_lock_bh(&sl->lock); - rcu_assign_pointer(tty->disc_data, NULL); + tty->disc_data = NULL; sl->tty = NULL; spin_unlock_bh(&sl->lock); - synchronize_rcu(); - flush_work(&sl->tx_work); - - slc_close(sl->dev); - unregister_candev(sl->dev); - rtnl_lock(); - slc_dealloc(sl); - rtnl_unlock(); -} - -static void slcan_hangup(struct tty_struct *tty) -{ - slcan_close(tty); + netdev_info(sl->dev, "slcan off %s.\n", tty->name); + free_candev(sl->dev); } /* Perform I/O control on an active SLCAN channel. */ @@ -987,10 +860,6 @@ static int slcan_ioctl(struct tty_struct *tty, unsigned int cmd, struct slcan *sl = (struct slcan *)tty->disc_data; unsigned int tmp; - /* First make sure we're connected. */ - if (!sl || sl->magic != SLCAN_MAGIC) - return -EINVAL; - switch (cmd) { case SIOCGIFNAME: tmp = strlen(sl->dev->name) + 1; @@ -1012,7 +881,6 @@ static struct tty_ldisc_ops slc_ldisc = { .name = "slcan", .open = slcan_open, .close = slcan_close, - .hangup = slcan_hangup, .ioctl = slcan_ioctl, .receive_buf = slcan_receive_buf, .write_wakeup = slcan_write_wakeup, @@ -1022,78 +890,21 @@ static int __init slcan_init(void) { int status; - if (maxdev < 4) - maxdev = 4; /* Sanity */ - pr_info("slcan: serial line CAN interface driver\n"); - pr_info("slcan: %d dynamic interface channels.\n", maxdev); - - slcan_devs = kcalloc(maxdev, sizeof(struct net_device *), GFP_KERNEL); - if (!slcan_devs) - return -ENOMEM; /* Fill in our line protocol discipline, and register it */ status = tty_register_ldisc(&slc_ldisc); - if (status) { + if (status) pr_err("slcan: can't register line discipline\n"); - kfree(slcan_devs); - } + return status; } static void __exit slcan_exit(void) { - int i; - struct net_device *dev; - struct slcan *sl; - unsigned long timeout = jiffies + HZ; - int busy = 0; - - if (!slcan_devs) - return; - - /* First of all: check for active disciplines and hangup them. - */ - do { - if (busy) - msleep_interruptible(100); - - busy = 0; - for (i = 0; i < maxdev; i++) { - dev = slcan_devs[i]; - if (!dev) - continue; - sl = netdev_priv(dev); - spin_lock_bh(&sl->lock); - if (sl->tty) { - busy++; - tty_hangup(sl->tty); - } - spin_unlock_bh(&sl->lock); - } - } while (busy && time_before(jiffies, timeout)); - - /* FIXME: hangup is async so we should wait when doing this second - * phase + /* This will only be called when all channels have been closed by + * userspace - tty_ldisc.c takes care of the module's refcount. */ - - for (i = 0; i < maxdev; i++) { - dev = slcan_devs[i]; - if (!dev) - continue; - - sl = netdev_priv(dev); - if (sl->tty) - netdev_err(dev, "tty discipline still running\n"); - - slc_close(dev); - unregister_candev(dev); - slc_dealloc(sl); - } - - kfree(slcan_devs); - slcan_devs = NULL; - tty_unregister_ldisc(&slc_ldisc); }