diff options
Diffstat (limited to 'drivers/tty/n_hdlc.c')
| -rw-r--r-- | drivers/tty/n_hdlc.c | 901 |
1 files changed, 352 insertions, 549 deletions
diff --git a/drivers/tty/n_hdlc.c b/drivers/tty/n_hdlc.c index 1b2db9a3038c..3c9dcb0928c6 100644 --- a/drivers/tty/n_hdlc.c +++ b/drivers/tty/n_hdlc.c @@ -1,3 +1,4 @@ +// SPDX-License-Identifier: GPL-1.0+ /* generic HDLC line discipline for Linux * * Written by Paul Fulghum paulkf@microgate.com @@ -11,15 +12,13 @@ * * Original release 01/11/99 * - * This code is released under the GNU General Public License (GPL) - * * This module implements the tty line discipline N_HDLC for use with * tty device drivers that support bit-synchronous HDLC communications. * * All HDLC data is frame oriented which means: * * 1. tty write calls represent one complete transmit frame of data - * The device driver should accept the complete frame or none of + * The device driver should accept the complete frame or none of * the frame (busy) in the write method. Each write call should have * a byte count in the range of 2-65535 bytes (2 is min HDLC frame * with 1 addr byte and 1 ctrl byte). The max byte count of 65535 @@ -40,7 +39,7 @@ * tty read calls. * * 3. tty read calls returns an entire frame of data or nothing. - * + * * 4. all send and receive data is considered raw. No processing * or translation is performed by the line discipline, regardless * of the tty flags @@ -77,8 +76,6 @@ * OF THE POSSIBILITY OF SUCH DAMAGE. */ -#define HDLC_MAGIC 0x239e - #include <linux/module.h> #include <linux/init.h> #include <linux/kernel.h> @@ -88,9 +85,6 @@ #include <linux/interrupt.h> #include <linux/ptrace.h> -#undef VERSION -#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch)) - #include <linux/poll.h> #include <linux/in.h> #include <linux/ioctl.h> @@ -102,103 +96,69 @@ #include <linux/if.h> #include <linux/bitops.h> -#include <asm/termios.h> -#include <asm/uaccess.h> +#include <linux/uaccess.h> +#include "tty.h" /* * Buffers for individual HDLC frames */ -#define MAX_HDLC_FRAME_SIZE 65535 +#define MAX_HDLC_FRAME_SIZE 65535 #define DEFAULT_RX_BUF_COUNT 10 #define MAX_RX_BUF_COUNT 60 #define DEFAULT_TX_BUF_COUNT 3 struct n_hdlc_buf { - struct n_hdlc_buf *link; - int count; - char buf[1]; + struct list_head list_item; + size_t count; + u8 buf[]; }; -#define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe) - struct n_hdlc_buf_list { - struct n_hdlc_buf *head; - struct n_hdlc_buf *tail; + struct list_head list; int count; spinlock_t spinlock; }; /** * struct n_hdlc - per device instance data structure - * @magic - magic value for structure - * @flags - miscellaneous control flags - * @tty - ptr to TTY structure - * @backup_tty - TTY to use if tty gets closed - * @tbusy - reentrancy flag for tx wakeup code - * @woke_up - FIXME: describe this field - * @tbuf - currently transmitting tx buffer - * @tx_buf_list - list of pending transmit frame buffers - * @rx_buf_list - list of received frame buffers - * @tx_free_buf_list - list unused transmit frame buffers - * @rx_free_buf_list - list unused received frame buffers + * @tbusy: reentrancy flag for tx wakeup code + * @woke_up: tx wakeup needs to be run again as it was called while @tbusy + * @tx_buf_list: list of pending transmit frame buffers + * @rx_buf_list: list of received frame buffers + * @tx_free_buf_list: list unused transmit frame buffers + * @rx_free_buf_list: list unused received frame buffers */ struct n_hdlc { - int magic; - __u32 flags; - struct tty_struct *tty; - struct tty_struct *backup_tty; - int tbusy; - int woke_up; - struct n_hdlc_buf *tbuf; + bool tbusy; + bool woke_up; struct n_hdlc_buf_list tx_buf_list; struct n_hdlc_buf_list rx_buf_list; struct n_hdlc_buf_list tx_free_buf_list; struct n_hdlc_buf_list rx_free_buf_list; + struct work_struct write_work; + struct tty_struct *tty_for_write_work; }; /* * HDLC buffer list manipulation functions */ -static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list); +static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, + struct n_hdlc_buf *buf); static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, struct n_hdlc_buf *buf); static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list); /* Local functions */ -static struct n_hdlc *n_hdlc_alloc (void); - -/* debug level can be set by insmod for debugging purposes */ -#define DEBUG_LEVEL_INFO 1 -static int debuglevel; +static struct n_hdlc *n_hdlc_alloc(void); +static void n_hdlc_tty_write_work(struct work_struct *work); /* max frame size for memory allocations */ static int maxframe = 4096; -/* TTY callbacks */ - -static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, - __u8 __user *buf, size_t nr); -static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, - const unsigned char *buf, size_t nr); -static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, - unsigned int cmd, unsigned long arg); -static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, - poll_table *wait); -static int n_hdlc_tty_open(struct tty_struct *tty); -static void n_hdlc_tty_close(struct tty_struct *tty); -static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp, - char *fp, int count); -static void n_hdlc_tty_wakeup(struct tty_struct *tty); - -#define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f))) - -#define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data)) -#define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty) - static void flush_rx_queue(struct tty_struct *tty) { - struct n_hdlc *n_hdlc = tty2n_hdlc(tty); + struct n_hdlc *n_hdlc = tty->disc_data; struct n_hdlc_buf *buf; while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list))) @@ -207,177 +167,95 @@ static void flush_rx_queue(struct tty_struct *tty) static void flush_tx_queue(struct tty_struct *tty) { - struct n_hdlc *n_hdlc = tty2n_hdlc(tty); + struct n_hdlc *n_hdlc = tty->disc_data; struct n_hdlc_buf *buf; - unsigned long flags; while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list))) n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf); - spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); - if (n_hdlc->tbuf) { - n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf); - n_hdlc->tbuf = NULL; - } - spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); } -static struct tty_ldisc_ops n_hdlc_ldisc = { - .owner = THIS_MODULE, - .magic = TTY_LDISC_MAGIC, - .name = "hdlc", - .open = n_hdlc_tty_open, - .close = n_hdlc_tty_close, - .read = n_hdlc_tty_read, - .write = n_hdlc_tty_write, - .ioctl = n_hdlc_tty_ioctl, - .poll = n_hdlc_tty_poll, - .receive_buf = n_hdlc_tty_receive, - .write_wakeup = n_hdlc_tty_wakeup, - .flush_buffer = flush_rx_queue, -}; - -/** - * n_hdlc_release - release an n_hdlc per device line discipline info structure - * @n_hdlc - per device line discipline info structure - */ -static void n_hdlc_release(struct n_hdlc *n_hdlc) +static void n_hdlc_free_buf_list(struct n_hdlc_buf_list *list) { - struct tty_struct *tty = n_hdlc2tty (n_hdlc); struct n_hdlc_buf *buf; - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__); - - /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ - wake_up_interruptible (&tty->read_wait); - wake_up_interruptible (&tty->write_wait); - - if (tty->disc_data == n_hdlc) - tty->disc_data = NULL; /* Break the tty->n_hdlc link */ - - /* Release transmit and receive buffers */ - for(;;) { - buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); - if (buf) { - kfree(buf); - } else - break; - } - for(;;) { - buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); - if (buf) { - kfree(buf); - } else - break; - } - for(;;) { - buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); - if (buf) { - kfree(buf); - } else - break; - } - for(;;) { - buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); - if (buf) { - kfree(buf); - } else - break; - } - kfree(n_hdlc->tbuf); - kfree(n_hdlc); - -} /* end of n_hdlc_release() */ + + do { + buf = n_hdlc_buf_get(list); + kfree(buf); + } while (buf); +} /** * n_hdlc_tty_close - line discipline close - * @tty - pointer to tty info structure + * @tty: pointer to tty info structure * * Called when the line discipline is changed to something * else, the tty is closed, or the tty detects a hangup. */ static void n_hdlc_tty_close(struct tty_struct *tty) { - struct n_hdlc *n_hdlc = tty2n_hdlc (tty); - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__); - - if (n_hdlc != NULL) { - if (n_hdlc->magic != HDLC_MAGIC) { - printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n"); - return; - } + struct n_hdlc *n_hdlc = tty->disc_data; + #if defined(TTY_NO_WRITE_SPLIT) - clear_bit(TTY_NO_WRITE_SPLIT,&tty->flags); + clear_bit(TTY_NO_WRITE_SPLIT, &tty->flags); #endif - tty->disc_data = NULL; - if (tty == n_hdlc->backup_tty) - n_hdlc->backup_tty = NULL; - if (tty != n_hdlc->tty) - return; - if (n_hdlc->backup_tty) { - n_hdlc->tty = n_hdlc->backup_tty; - } else { - n_hdlc_release (n_hdlc); - } - } - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__); - + tty->disc_data = NULL; + + /* Ensure that the n_hdlcd process is not hanging on select()/poll() */ + wake_up_interruptible(&tty->read_wait); + wake_up_interruptible(&tty->write_wait); + + cancel_work_sync(&n_hdlc->write_work); + + n_hdlc_free_buf_list(&n_hdlc->rx_free_buf_list); + n_hdlc_free_buf_list(&n_hdlc->tx_free_buf_list); + n_hdlc_free_buf_list(&n_hdlc->rx_buf_list); + n_hdlc_free_buf_list(&n_hdlc->tx_buf_list); + kfree(n_hdlc); } /* end of n_hdlc_tty_close() */ /** * n_hdlc_tty_open - called when line discipline changed to n_hdlc - * @tty - pointer to tty info structure + * @tty: pointer to tty info structure * * Returns 0 if success, otherwise error code */ -static int n_hdlc_tty_open (struct tty_struct *tty) +static int n_hdlc_tty_open(struct tty_struct *tty) { - struct n_hdlc *n_hdlc = tty2n_hdlc (tty); + struct n_hdlc *n_hdlc = tty->disc_data; + + pr_debug("%s() called (device=%s)\n", __func__, tty->name); - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n", - __FILE__,__LINE__, - tty->name); - /* There should not be an existing table for this slot. */ if (n_hdlc) { - printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" ); + pr_err("%s: tty already associated!\n", __func__); return -EEXIST; } - + n_hdlc = n_hdlc_alloc(); if (!n_hdlc) { - printk (KERN_ERR "n_hdlc_alloc failed\n"); + pr_err("%s: n_hdlc_alloc failed\n", __func__); return -ENFILE; } - + + INIT_WORK(&n_hdlc->write_work, n_hdlc_tty_write_work); + n_hdlc->tty_for_write_work = tty; tty->disc_data = n_hdlc; - n_hdlc->tty = tty; tty->receive_room = 65536; - -#if defined(TTY_NO_WRITE_SPLIT) + /* change tty_io write() to not split large writes into 8K chunks */ - set_bit(TTY_NO_WRITE_SPLIT,&tty->flags); -#endif - + set_bit(TTY_NO_WRITE_SPLIT, &tty->flags); + /* flush receive data from driver */ tty_driver_flush_buffer(tty); - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__); - + return 0; - + } /* end of n_tty_hdlc_open() */ /** * n_hdlc_send_frames - send frames on pending send buffer list - * @n_hdlc - pointer to ldisc instance data - * @tty - pointer to tty instance data + * @n_hdlc: pointer to ldisc instance data + * @tty: pointer to tty instance data * * Send frames on pending send buffer list until the driver does not accept a * frame (busy) this function is called after adding a frame to the send buffer @@ -385,217 +263,176 @@ static int n_hdlc_tty_open (struct tty_struct *tty) */ static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty) { - register int actual; - unsigned long flags; struct n_hdlc_buf *tbuf; + ssize_t actual; - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__); - check_again: - - spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); - if (n_hdlc->tbusy) { - n_hdlc->woke_up = 1; - spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); - return; +check_again: + scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) { + if (n_hdlc->tbusy) { + n_hdlc->woke_up = true; + return; + } + n_hdlc->tbusy = true; + n_hdlc->woke_up = false; } - n_hdlc->tbusy = 1; - n_hdlc->woke_up = 0; - spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); - - /* get current transmit buffer or get new transmit */ - /* buffer from list of pending transmit buffers */ - - tbuf = n_hdlc->tbuf; - if (!tbuf) - tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); - + + tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); while (tbuf) { - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)sending frame %p, count=%d\n", - __FILE__,__LINE__,tbuf,tbuf->count); - + pr_debug("sending frame %p, count=%zu\n", tbuf, tbuf->count); + /* Send the next block of data to device */ set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); actual = tty->ops->write(tty, tbuf->buf, tbuf->count); /* rollback was possible and has been done */ if (actual == -ERESTARTSYS) { - n_hdlc->tbuf = tbuf; + n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); break; } /* if transmit error, throw frame away by */ /* pretending it was accepted by driver */ if (actual < 0) actual = tbuf->count; - + if (actual == tbuf->count) { - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)frame %p completed\n", - __FILE__,__LINE__,tbuf); - + pr_debug("frame %p completed\n", tbuf); + /* free current transmit buffer */ n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf); - - /* this tx buffer is done */ - n_hdlc->tbuf = NULL; - + /* wait up sleeping writers */ wake_up_interruptible(&tty->write_wait); - + /* get next pending transmit buffer */ tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list); } else { - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)frame %p pending\n", - __FILE__,__LINE__,tbuf); - - /* buffer not accepted by driver */ - /* set this buffer as pending buffer */ - n_hdlc->tbuf = tbuf; + pr_debug("frame %p pending\n", tbuf); + + /* + * the buffer was not accepted by driver, + * return it back into tx queue + */ + n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf); break; } } - + if (!tbuf) clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); - + /* Clear the re-entry flag */ - spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags); - n_hdlc->tbusy = 0; - spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags); - - if (n_hdlc->woke_up) - goto check_again; - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_send_frames() exit\n",__FILE__,__LINE__); - + scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) + n_hdlc->tbusy = false; + + if (n_hdlc->woke_up) + goto check_again; } /* end of n_hdlc_send_frames() */ /** - * n_hdlc_tty_wakeup - Callback for transmit wakeup - * @tty - pointer to associated tty instance data + * n_hdlc_tty_write_work - Asynchronous callback for transmit wakeup + * @work: pointer to work_struct * * Called when low level device driver can accept more send data. */ -static void n_hdlc_tty_wakeup(struct tty_struct *tty) +static void n_hdlc_tty_write_work(struct work_struct *work) { - struct n_hdlc *n_hdlc = tty2n_hdlc(tty); + struct n_hdlc *n_hdlc = container_of(work, struct n_hdlc, write_work); + struct tty_struct *tty = n_hdlc->tty_for_write_work; - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__); - - if (!n_hdlc) - return; + n_hdlc_send_frames(n_hdlc, tty); +} /* end of n_hdlc_tty_write_work() */ - if (tty != n_hdlc->tty) { - clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags); - return; - } +/** + * n_hdlc_tty_wakeup - Callback for transmit wakeup + * @tty: pointer to associated tty instance data + * + * Called when low level device driver can accept more send data. + */ +static void n_hdlc_tty_wakeup(struct tty_struct *tty) +{ + struct n_hdlc *n_hdlc = tty->disc_data; - n_hdlc_send_frames (n_hdlc, tty); - + schedule_work(&n_hdlc->write_work); } /* end of n_hdlc_tty_wakeup() */ /** * n_hdlc_tty_receive - Called by tty driver when receive data is available - * @tty - pointer to tty instance data - * @data - pointer to received data - * @flags - pointer to flags for data - * @count - count of received data in bytes + * @tty: pointer to tty instance data + * @data: pointer to received data + * @flags: pointer to flags for data + * @count: count of received data in bytes * * Called by tty low level driver when receive data is available. Data is * interpreted as one HDLC frame. */ -static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data, - char *flags, int count) +static void n_hdlc_tty_receive(struct tty_struct *tty, const u8 *data, + const u8 *flags, size_t count) { - register struct n_hdlc *n_hdlc = tty2n_hdlc (tty); + register struct n_hdlc *n_hdlc = tty->disc_data; register struct n_hdlc_buf *buf; - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_receive() called count=%d\n", - __FILE__,__LINE__, count); - - /* This can happen if stuff comes in on the backup tty */ - if (!n_hdlc || tty != n_hdlc->tty) - return; - - /* verify line is using HDLC discipline */ - if (n_hdlc->magic != HDLC_MAGIC) { - printk("%s(%d) line not using HDLC discipline\n", - __FILE__,__LINE__); - return; - } - - if ( count>maxframe ) { - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d) rx count>maxframesize, data discarded\n", - __FILE__,__LINE__); + pr_debug("%s() called count=%zu\n", __func__, count); + + if (count > maxframe) { + pr_debug("rx count>maxframesize, data discarded\n"); return; } - /* get a free HDLC buffer */ + /* get a free HDLC buffer */ buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list); if (!buf) { - /* no buffers in free list, attempt to allocate another rx buffer */ - /* unless the maximum count has been reached */ + /* + * no buffers in free list, attempt to allocate another rx + * buffer unless the maximum count has been reached + */ if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT) - buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC); + buf = kmalloc(struct_size(buf, buf, maxframe), + GFP_ATOMIC); } - + if (!buf) { - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d) no more rx buffers, data discarded\n", - __FILE__,__LINE__); + pr_debug("no more rx buffers, data discarded\n"); return; } - + /* copy received data to HDLC buffer */ - memcpy(buf->buf,data,count); - buf->count=count; + memcpy(buf->buf, data, count); + buf->count = count; /* add HDLC buffer to list of received frames */ n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf); - + /* wake up any blocked reads and perform async signalling */ - wake_up_interruptible (&tty->read_wait); - if (n_hdlc->tty->fasync != NULL) - kill_fasync (&n_hdlc->tty->fasync, SIGIO, POLL_IN); + wake_up_interruptible(&tty->read_wait); + if (tty->fasync != NULL) + kill_fasync(&tty->fasync, SIGIO, POLL_IN); } /* end of n_hdlc_tty_receive() */ /** * n_hdlc_tty_read - Called to retrieve one frame of data (if available) - * @tty - pointer to tty instance data - * @file - pointer to open file object - * @buf - pointer to returned data buffer - * @nr - size of returned data buffer - * + * @tty: pointer to tty instance data + * @file: pointer to open file object + * @kbuf: pointer to returned data buffer + * @nr: size of returned data buffer + * @cookie: stored rbuf from previous run + * @offset: offset into the data buffer + * * Returns the number of bytes returned or error code. */ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, - __u8 __user *buf, size_t nr) + u8 *kbuf, size_t nr, void **cookie, + unsigned long offset) { - struct n_hdlc *n_hdlc = tty2n_hdlc(tty); + struct n_hdlc *n_hdlc = tty->disc_data; int ret = 0; struct n_hdlc_buf *rbuf; DECLARE_WAITQUEUE(wait, current); - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_read() called\n",__FILE__,__LINE__); - - /* Validate the pointers */ - if (!n_hdlc) - return -EIO; - - /* verify user access to buffer */ - if (!access_ok(VERIFY_WRITE, buf, nr)) { - printk(KERN_WARNING "%s(%d) n_hdlc_tty_read() can't verify user " - "buffer\n", __FILE__, __LINE__); - return -EFAULT; - } + /* Is this a repeated call for an rbuf we already found earlier? */ + rbuf = *cookie; + if (rbuf) + goto have_rbuf; add_wait_queue(&tty->read_wait, &wait); @@ -610,27 +447,11 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, set_current_state(TASK_INTERRUPTIBLE); rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list); - if (rbuf) { - if (rbuf->count > nr) { - /* too large for caller's buffer */ - ret = -EOVERFLOW; - } else { - if (copy_to_user(buf, rbuf->buf, rbuf->count)) - ret = -EFAULT; - else - ret = rbuf->count; - } - - if (n_hdlc->rx_free_buf_list.count > - DEFAULT_RX_BUF_COUNT) - kfree(rbuf); - else - n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); + if (rbuf) break; - } - + /* no data */ - if (file->f_flags & O_NONBLOCK) { + if (tty_io_nonblock(tty, file)) { ret = -EAGAIN; break; } @@ -646,71 +467,84 @@ static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file, remove_wait_queue(&tty->read_wait, &wait); __set_current_state(TASK_RUNNING); + if (!rbuf) + return ret; + *cookie = rbuf; + +have_rbuf: + /* Have we used it up entirely? */ + if (offset >= rbuf->count) + goto done_with_rbuf; + + /* More data to go, but can't copy any more? EOVERFLOW */ + ret = -EOVERFLOW; + if (!nr) + goto done_with_rbuf; + + /* Copy as much data as possible */ + ret = rbuf->count - offset; + if (ret > nr) + ret = nr; + memcpy(kbuf, rbuf->buf+offset, ret); + offset += ret; + + /* If we still have data left, we leave the rbuf in the cookie */ + if (offset < rbuf->count) + return ret; + +done_with_rbuf: + *cookie = NULL; + + if (n_hdlc->rx_free_buf_list.count > DEFAULT_RX_BUF_COUNT) + kfree(rbuf); + else + n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, rbuf); + return ret; - + } /* end of n_hdlc_tty_read() */ /** * n_hdlc_tty_write - write a single frame of data to device - * @tty - pointer to associated tty device instance data - * @file - pointer to file object data - * @data - pointer to transmit data (one frame) - * @count - size of transmit frame in bytes - * + * @tty: pointer to associated tty device instance data + * @file: pointer to file object data + * @data: pointer to transmit data (one frame) + * @count: size of transmit frame in bytes + * * Returns the number of bytes written (or error code). */ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, - const unsigned char *data, size_t count) + const u8 *data, size_t count) { - struct n_hdlc *n_hdlc = tty2n_hdlc (tty); - int error = 0; + struct n_hdlc *n_hdlc = tty->disc_data; DECLARE_WAITQUEUE(wait, current); struct n_hdlc_buf *tbuf; + ssize_t error = 0; - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_write() called count=%Zd\n", - __FILE__,__LINE__,count); - - /* Verify pointers */ - if (!n_hdlc) - return -EIO; - - if (n_hdlc->magic != HDLC_MAGIC) - return -EIO; + pr_debug("%s() called count=%zd\n", __func__, count); /* verify frame size */ - if (count > maxframe ) { - if (debuglevel & DEBUG_LEVEL_INFO) - printk (KERN_WARNING - "n_hdlc_tty_write: truncating user packet " - "from %lu to %d\n", (unsigned long) count, - maxframe ); + if (count > maxframe) { + pr_debug("%s: truncating user packet from %zu to %d\n", + __func__, count, maxframe); count = maxframe; } - + add_wait_queue(&tty->write_wait, &wait); for (;;) { set_current_state(TASK_INTERRUPTIBLE); - + tbuf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list); if (tbuf) break; - if (file->f_flags & O_NONBLOCK) { + if (tty_io_nonblock(tty, file)) { error = -EAGAIN; break; } schedule(); - - n_hdlc = tty2n_hdlc (tty); - if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC || - tty != n_hdlc->tty) { - printk("n_hdlc_tty_write: %p invalid after wait!\n", n_hdlc); - error = -EIO; - break; - } - + if (signal_pending(current)) { error = -EINTR; break; @@ -720,68 +554,62 @@ static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file, __set_current_state(TASK_RUNNING); remove_wait_queue(&tty->write_wait, &wait); - if (!error) { + if (!error) { /* Retrieve the user's buffer */ memcpy(tbuf->buf, data, count); /* Send the data */ tbuf->count = error = count; - n_hdlc_buf_put(&n_hdlc->tx_buf_list,tbuf); - n_hdlc_send_frames(n_hdlc,tty); + n_hdlc_buf_put(&n_hdlc->tx_buf_list, tbuf); + n_hdlc_send_frames(n_hdlc, tty); } return error; - + } /* end of n_hdlc_tty_write() */ /** * n_hdlc_tty_ioctl - process IOCTL system call for the tty device. - * @tty - pointer to tty instance data - * @file - pointer to open file object for device - * @cmd - IOCTL command code - * @arg - argument for IOCTL call (cmd dependent) + * @tty: pointer to tty instance data + * @cmd: IOCTL command code + * @arg: argument for IOCTL call (cmd dependent) * * Returns command dependent result. */ -static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, - unsigned int cmd, unsigned long arg) +static int n_hdlc_tty_ioctl(struct tty_struct *tty, unsigned int cmd, + unsigned long arg) { - struct n_hdlc *n_hdlc = tty2n_hdlc (tty); - int error = 0; + struct n_hdlc *n_hdlc = tty->disc_data; int count; - unsigned long flags; - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_ioctl() called %d\n", - __FILE__,__LINE__,cmd); - - /* Verify the status of the device */ - if (!n_hdlc || n_hdlc->magic != HDLC_MAGIC) - return -EBADF; + struct n_hdlc_buf *buf = NULL; + + pr_debug("%s() called %d\n", __func__, cmd); switch (cmd) { case FIONREAD: /* report count of read data available */ /* in next available frame (if any) */ - spin_lock_irqsave(&n_hdlc->rx_buf_list.spinlock,flags); - if (n_hdlc->rx_buf_list.head) - count = n_hdlc->rx_buf_list.head->count; - else - count = 0; - spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock,flags); - error = put_user(count, (int __user *)arg); - break; + scoped_guard(spinlock_irqsave, &n_hdlc->rx_buf_list.spinlock) { + buf = list_first_entry_or_null(&n_hdlc->rx_buf_list.list, + struct n_hdlc_buf, list_item); + if (buf) + count = buf->count; + else + count = 0; + } + return put_user(count, (int __user *)arg); case TIOCOUTQ: /* get the pending tx byte count in the driver */ count = tty_chars_in_buffer(tty); /* add size of next output frame in queue */ - spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock,flags); - if (n_hdlc->tx_buf_list.head) - count += n_hdlc->tx_buf_list.head->count; - spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock,flags); - error = put_user(count, (int __user *)arg); - break; + scoped_guard(spinlock_irqsave, &n_hdlc->tx_buf_list.spinlock) { + buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list, + struct n_hdlc_buf, list_item); + if (buf) + count += buf->count; + } + return put_user(count, (int __user *)arg); case TCFLSH: switch (arg) { @@ -789,56 +617,67 @@ static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file, case TCOFLUSH: flush_tx_queue(tty); } - /* fall through to default */ + fallthrough; /* to default */ default: - error = n_tty_ioctl_helper(tty, file, cmd, arg); - break; + return n_tty_ioctl_helper(tty, cmd, arg); } - return error; - } /* end of n_hdlc_tty_ioctl() */ /** * n_hdlc_tty_poll - TTY callback for poll system call - * @tty - pointer to tty instance data - * @filp - pointer to open file object for device - * @poll_table - wait queue for operations - * + * @tty: pointer to tty instance data + * @filp: pointer to open file object for device + * @wait: wait queue for operations + * * Determine which operations (read/write) will not block and return info * to caller. * Returns a bit mask containing info on which ops will not block. */ -static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, +static __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, poll_table *wait) { - struct n_hdlc *n_hdlc = tty2n_hdlc (tty); - unsigned int mask = 0; - - if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_tty_poll() called\n",__FILE__,__LINE__); - - if (n_hdlc && n_hdlc->magic == HDLC_MAGIC && tty == n_hdlc->tty) { - /* queue current process into any wait queue that */ - /* may awaken in the future (read and write) */ - - poll_wait(filp, &tty->read_wait, wait); - poll_wait(filp, &tty->write_wait, wait); - - /* set bits for operations that won't block */ - if (n_hdlc->rx_buf_list.head) - mask |= POLLIN | POLLRDNORM; /* readable */ - if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) - mask |= POLLHUP; - if (tty_hung_up_p(filp)) - mask |= POLLHUP; - if (!tty_is_writelocked(tty) && - n_hdlc->tx_free_buf_list.head) - mask |= POLLOUT | POLLWRNORM; /* writable */ - } + struct n_hdlc *n_hdlc = tty->disc_data; + __poll_t mask = 0; + + /* + * queue the current process into any wait queue that may awaken in the + * future (read and write) + */ + poll_wait(filp, &tty->read_wait, wait); + poll_wait(filp, &tty->write_wait, wait); + + /* set bits for operations that won't block */ + if (!list_empty(&n_hdlc->rx_buf_list.list)) + mask |= EPOLLIN | EPOLLRDNORM; /* readable */ + if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) + mask |= EPOLLHUP; + if (tty_hung_up_p(filp)) + mask |= EPOLLHUP; + if (!tty_is_writelocked(tty) && + !list_empty(&n_hdlc->tx_free_buf_list.list)) + mask |= EPOLLOUT | EPOLLWRNORM; /* writable */ + return mask; } /* end of n_hdlc_tty_poll() */ +static void n_hdlc_alloc_buf(struct n_hdlc_buf_list *list, unsigned int count, + const char *name) +{ + struct n_hdlc_buf *buf; + unsigned int i; + + for (i = 0; i < count; i++) { + buf = kmalloc(struct_size(buf, buf, maxframe), GFP_KERNEL); + if (!buf) { + pr_debug("%s(), kmalloc() failed for %s buffer %u\n", + __func__, name, i); + return; + } + n_hdlc_buf_put(list, buf); + } +} + /** * n_hdlc_alloc - allocate an n_hdlc instance data structure * @@ -846,160 +685,124 @@ static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp, */ static struct n_hdlc *n_hdlc_alloc(void) { - struct n_hdlc_buf *buf; - int i; - struct n_hdlc *n_hdlc = kmalloc(sizeof(*n_hdlc), GFP_KERNEL); + struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL); if (!n_hdlc) return NULL; - memset(n_hdlc, 0, sizeof(*n_hdlc)); - - n_hdlc_buf_list_init(&n_hdlc->rx_free_buf_list); - n_hdlc_buf_list_init(&n_hdlc->tx_free_buf_list); - n_hdlc_buf_list_init(&n_hdlc->rx_buf_list); - n_hdlc_buf_list_init(&n_hdlc->tx_buf_list); - - /* allocate free rx buffer list */ - for(i=0;i<DEFAULT_RX_BUF_COUNT;i++) { - buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); - if (buf) - n_hdlc_buf_put(&n_hdlc->rx_free_buf_list,buf); - else if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_alloc(), kalloc() failed for rx buffer %d\n",__FILE__,__LINE__, i); - } - - /* allocate free tx buffer list */ - for(i=0;i<DEFAULT_TX_BUF_COUNT;i++) { - buf = kmalloc(N_HDLC_BUF_SIZE, GFP_KERNEL); - if (buf) - n_hdlc_buf_put(&n_hdlc->tx_free_buf_list,buf); - else if (debuglevel >= DEBUG_LEVEL_INFO) - printk("%s(%d)n_hdlc_alloc(), kalloc() failed for tx buffer %d\n",__FILE__,__LINE__, i); - } - - /* Initialize the control block */ - n_hdlc->magic = HDLC_MAGIC; - n_hdlc->flags = 0; - + spin_lock_init(&n_hdlc->rx_free_buf_list.spinlock); + spin_lock_init(&n_hdlc->tx_free_buf_list.spinlock); + spin_lock_init(&n_hdlc->rx_buf_list.spinlock); + spin_lock_init(&n_hdlc->tx_buf_list.spinlock); + + INIT_LIST_HEAD(&n_hdlc->rx_free_buf_list.list); + INIT_LIST_HEAD(&n_hdlc->tx_free_buf_list.list); + INIT_LIST_HEAD(&n_hdlc->rx_buf_list.list); + INIT_LIST_HEAD(&n_hdlc->tx_buf_list.list); + + n_hdlc_alloc_buf(&n_hdlc->rx_free_buf_list, DEFAULT_RX_BUF_COUNT, "rx"); + n_hdlc_alloc_buf(&n_hdlc->tx_free_buf_list, DEFAULT_TX_BUF_COUNT, "tx"); + return n_hdlc; - + } /* end of n_hdlc_alloc() */ /** - * n_hdlc_buf_list_init - initialize specified HDLC buffer list - * @list - pointer to buffer list + * n_hdlc_buf_return - put the HDLC buffer after the head of the specified list + * @buf_list: pointer to the buffer list + * @buf: pointer to the buffer */ -static void n_hdlc_buf_list_init(struct n_hdlc_buf_list *list) +static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list, + struct n_hdlc_buf *buf) { - memset(list, 0, sizeof(*list)); - spin_lock_init(&list->spinlock); -} /* end of n_hdlc_buf_list_init() */ + guard(spinlock_irqsave)(&buf_list->spinlock); + + list_add(&buf->list_item, &buf_list->list); + buf_list->count++; +} /** * n_hdlc_buf_put - add specified HDLC buffer to tail of specified list - * @list - pointer to buffer list - * @buf - pointer to buffer + * @buf_list: pointer to buffer list + * @buf: pointer to buffer */ -static void n_hdlc_buf_put(struct n_hdlc_buf_list *list, +static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list, struct n_hdlc_buf *buf) { - unsigned long flags; - spin_lock_irqsave(&list->spinlock,flags); - - buf->link=NULL; - if (list->tail) - list->tail->link = buf; - else - list->head = buf; - list->tail = buf; - (list->count)++; - - spin_unlock_irqrestore(&list->spinlock,flags); - + guard(spinlock_irqsave)(&buf_list->spinlock); + + list_add_tail(&buf->list_item, &buf_list->list); + buf_list->count++; } /* end of n_hdlc_buf_put() */ /** * n_hdlc_buf_get - remove and return an HDLC buffer from list - * @list - pointer to HDLC buffer list - * + * @buf_list: pointer to HDLC buffer list + * * Remove and return an HDLC buffer from the head of the specified HDLC buffer * list. * Returns a pointer to HDLC buffer if available, otherwise %NULL. */ -static struct n_hdlc_buf* n_hdlc_buf_get(struct n_hdlc_buf_list *list) +static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *buf_list) { - unsigned long flags; struct n_hdlc_buf *buf; - spin_lock_irqsave(&list->spinlock,flags); - - buf = list->head; + + guard(spinlock_irqsave)(&buf_list->spinlock); + + buf = list_first_entry_or_null(&buf_list->list, + struct n_hdlc_buf, list_item); if (buf) { - list->head = buf->link; - (list->count)--; + list_del(&buf->list_item); + buf_list->count--; } - if (!list->head) - list->tail = NULL; - - spin_unlock_irqrestore(&list->spinlock,flags); + return buf; - } /* end of n_hdlc_buf_get() */ -static char hdlc_banner[] __initdata = - KERN_INFO "HDLC line discipline maxframe=%u\n"; -static char hdlc_register_ok[] __initdata = - KERN_INFO "N_HDLC line discipline registered.\n"; -static char hdlc_register_fail[] __initdata = - KERN_ERR "error registering line discipline: %d\n"; -static char hdlc_init_fail[] __initdata = - KERN_INFO "N_HDLC: init failure %d\n"; +static struct tty_ldisc_ops n_hdlc_ldisc = { + .owner = THIS_MODULE, + .num = N_HDLC, + .name = "hdlc", + .open = n_hdlc_tty_open, + .close = n_hdlc_tty_close, + .read = n_hdlc_tty_read, + .write = n_hdlc_tty_write, + .ioctl = n_hdlc_tty_ioctl, + .poll = n_hdlc_tty_poll, + .receive_buf = n_hdlc_tty_receive, + .write_wakeup = n_hdlc_tty_wakeup, + .flush_buffer = flush_rx_queue, +}; static int __init n_hdlc_init(void) { int status; /* range check maxframe arg */ - if (maxframe < 4096) - maxframe = 4096; - else if (maxframe > 65535) - maxframe = 65535; + maxframe = clamp(maxframe, 4096, MAX_HDLC_FRAME_SIZE); - printk(hdlc_banner, maxframe); - - status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc); + status = tty_register_ldisc(&n_hdlc_ldisc); if (!status) - printk(hdlc_register_ok); + pr_info("N_HDLC line discipline registered with maxframe=%d\n", + maxframe); else - printk(hdlc_register_fail, status); + pr_err("N_HDLC: error registering line discipline: %d\n", + status); - if (status) - printk(hdlc_init_fail, status); return status; - -} /* end of init_module() */ -static char hdlc_unregister_ok[] __exitdata = - KERN_INFO "N_HDLC: line discipline unregistered\n"; -static char hdlc_unregister_fail[] __exitdata = - KERN_ERR "N_HDLC: can't unregister line discipline (err = %d)\n"; +} /* end of init_module() */ static void __exit n_hdlc_exit(void) { - /* Release tty registration of line discipline */ - int status = tty_unregister_ldisc(N_HDLC); - - if (status) - printk(hdlc_unregister_fail, status); - else - printk(hdlc_unregister_ok); + tty_unregister_ldisc(&n_hdlc_ldisc); } module_init(n_hdlc_init); module_exit(n_hdlc_exit); +MODULE_DESCRIPTION("HDLC line discipline support"); MODULE_LICENSE("GPL"); MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com"); -module_param(debuglevel, int, 0); module_param(maxframe, int, 0); MODULE_ALIAS_LDISC(N_HDLC); |