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According to Greg, in the context of magic numbers as defined in magic-number.rst, "the tty layer should not need this and I'll gladly take patches" Acked-by: Jiri Slaby <jirislaby@kernel.org> Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz> Ref: https://lore.kernel.org/linux-doc/YyMlovoskUcHLEb7@kroah.com/ Link: https://lore.kernel.org/r/c31d228302da3f426cebf6fcff855181a5590a66.1663288066.git.nabijaczleweli@nabijaczleweli.xyz Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
828 lines
22 KiB
C
828 lines
22 KiB
C
// SPDX-License-Identifier: GPL-1.0+
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/* generic HDLC line discipline for Linux
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*
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* Written by Paul Fulghum paulkf@microgate.com
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* for Microgate Corporation
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*
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* Microgate and SyncLink are registered trademarks of Microgate Corporation
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*
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* Adapted from ppp.c, written by Michael Callahan <callahan@maths.ox.ac.uk>,
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* Al Longyear <longyear@netcom.com>,
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* Paul Mackerras <Paul.Mackerras@cs.anu.edu.au>
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*
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* Original release 01/11/99
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*
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* This module implements the tty line discipline N_HDLC for use with
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* tty device drivers that support bit-synchronous HDLC communications.
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*
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* All HDLC data is frame oriented which means:
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*
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* 1. tty write calls represent one complete transmit frame of data
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* The device driver should accept the complete frame or none of
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* the frame (busy) in the write method. Each write call should have
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* a byte count in the range of 2-65535 bytes (2 is min HDLC frame
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* with 1 addr byte and 1 ctrl byte). The max byte count of 65535
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* should include any crc bytes required. For example, when using
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* CCITT CRC32, 4 crc bytes are required, so the maximum size frame
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* the application may transmit is limited to 65531 bytes. For CCITT
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* CRC16, the maximum application frame size would be 65533.
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*
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*
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* 2. receive callbacks from the device driver represents
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* one received frame. The device driver should bypass
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* the tty flip buffer and call the line discipline receive
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* callback directly to avoid fragmenting or concatenating
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* multiple frames into a single receive callback.
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*
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* The HDLC line discipline queues the receive frames in separate
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* buffers so complete receive frames can be returned by the
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* tty read calls.
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*
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* 3. tty read calls returns an entire frame of data or nothing.
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*
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* 4. all send and receive data is considered raw. No processing
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* or translation is performed by the line discipline, regardless
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* of the tty flags
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*
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* 5. When line discipline is queried for the amount of receive
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* data available (FIOC), 0 is returned if no data available,
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* otherwise the count of the next available frame is returned.
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* (instead of the sum of all received frame counts).
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*
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* These conventions allow the standard tty programming interface
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* to be used for synchronous HDLC applications when used with
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* this line discipline (or another line discipline that is frame
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* oriented such as N_PPP).
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*
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* The SyncLink driver (synclink.c) implements both asynchronous
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* (using standard line discipline N_TTY) and synchronous HDLC
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* (using N_HDLC) communications, with the latter using the above
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* conventions.
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*
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* This implementation is very basic and does not maintain
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* any statistics. The main point is to enforce the raw data
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* and frame orientation of HDLC communications.
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*
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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*/
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#include <linux/module.h>
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#include <linux/init.h>
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#include <linux/kernel.h>
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#include <linux/sched.h>
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#include <linux/types.h>
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#include <linux/fcntl.h>
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#include <linux/interrupt.h>
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#include <linux/ptrace.h>
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#include <linux/poll.h>
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#include <linux/in.h>
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#include <linux/ioctl.h>
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#include <linux/slab.h>
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#include <linux/tty.h>
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#include <linux/errno.h>
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#include <linux/string.h> /* used in new tty drivers */
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#include <linux/signal.h> /* used in new tty drivers */
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#include <linux/if.h>
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#include <linux/bitops.h>
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#include <linux/uaccess.h>
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#include "tty.h"
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/*
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* Buffers for individual HDLC frames
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*/
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#define MAX_HDLC_FRAME_SIZE 65535
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#define DEFAULT_RX_BUF_COUNT 10
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#define MAX_RX_BUF_COUNT 60
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#define DEFAULT_TX_BUF_COUNT 3
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struct n_hdlc_buf {
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struct list_head list_item;
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int count;
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char buf[];
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};
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struct n_hdlc_buf_list {
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struct list_head list;
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int count;
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spinlock_t spinlock;
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};
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/**
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* struct n_hdlc - per device instance data structure
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* @tbusy: reentrancy flag for tx wakeup code
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* @woke_up: tx wakeup needs to be run again as it was called while @tbusy
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* @tx_buf_list: list of pending transmit frame buffers
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* @rx_buf_list: list of received frame buffers
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* @tx_free_buf_list: list unused transmit frame buffers
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* @rx_free_buf_list: list unused received frame buffers
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*/
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struct n_hdlc {
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bool tbusy;
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bool woke_up;
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struct n_hdlc_buf_list tx_buf_list;
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struct n_hdlc_buf_list rx_buf_list;
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struct n_hdlc_buf_list tx_free_buf_list;
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struct n_hdlc_buf_list rx_free_buf_list;
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struct work_struct write_work;
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struct tty_struct *tty_for_write_work;
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};
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/*
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* HDLC buffer list manipulation functions
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*/
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static void n_hdlc_buf_return(struct n_hdlc_buf_list *buf_list,
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struct n_hdlc_buf *buf);
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static void n_hdlc_buf_put(struct n_hdlc_buf_list *list,
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struct n_hdlc_buf *buf);
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static struct n_hdlc_buf *n_hdlc_buf_get(struct n_hdlc_buf_list *list);
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/* Local functions */
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static struct n_hdlc *n_hdlc_alloc(void);
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static void n_hdlc_tty_write_work(struct work_struct *work);
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/* max frame size for memory allocations */
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static int maxframe = 4096;
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static void flush_rx_queue(struct tty_struct *tty)
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{
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struct n_hdlc *n_hdlc = tty->disc_data;
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struct n_hdlc_buf *buf;
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while ((buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list)))
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n_hdlc_buf_put(&n_hdlc->rx_free_buf_list, buf);
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}
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static void flush_tx_queue(struct tty_struct *tty)
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{
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struct n_hdlc *n_hdlc = tty->disc_data;
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struct n_hdlc_buf *buf;
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while ((buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list)))
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n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, buf);
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}
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static void n_hdlc_free_buf_list(struct n_hdlc_buf_list *list)
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{
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struct n_hdlc_buf *buf;
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do {
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buf = n_hdlc_buf_get(list);
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kfree(buf);
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} while (buf);
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}
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/**
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* n_hdlc_tty_close - line discipline close
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* @tty: pointer to tty info structure
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*
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* Called when the line discipline is changed to something
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* else, the tty is closed, or the tty detects a hangup.
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*/
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static void n_hdlc_tty_close(struct tty_struct *tty)
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{
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struct n_hdlc *n_hdlc = tty->disc_data;
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#if defined(TTY_NO_WRITE_SPLIT)
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clear_bit(TTY_NO_WRITE_SPLIT, &tty->flags);
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#endif
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tty->disc_data = NULL;
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/* Ensure that the n_hdlcd process is not hanging on select()/poll() */
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wake_up_interruptible(&tty->read_wait);
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wake_up_interruptible(&tty->write_wait);
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cancel_work_sync(&n_hdlc->write_work);
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n_hdlc_free_buf_list(&n_hdlc->rx_free_buf_list);
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n_hdlc_free_buf_list(&n_hdlc->tx_free_buf_list);
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n_hdlc_free_buf_list(&n_hdlc->rx_buf_list);
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n_hdlc_free_buf_list(&n_hdlc->tx_buf_list);
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kfree(n_hdlc);
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} /* end of n_hdlc_tty_close() */
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/**
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* n_hdlc_tty_open - called when line discipline changed to n_hdlc
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* @tty: pointer to tty info structure
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*
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* Returns 0 if success, otherwise error code
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*/
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static int n_hdlc_tty_open(struct tty_struct *tty)
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{
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struct n_hdlc *n_hdlc = tty->disc_data;
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pr_debug("%s() called (device=%s)\n", __func__, tty->name);
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/* There should not be an existing table for this slot. */
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if (n_hdlc) {
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pr_err("%s: tty already associated!\n", __func__);
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return -EEXIST;
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}
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n_hdlc = n_hdlc_alloc();
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if (!n_hdlc) {
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pr_err("%s: n_hdlc_alloc failed\n", __func__);
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return -ENFILE;
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}
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INIT_WORK(&n_hdlc->write_work, n_hdlc_tty_write_work);
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n_hdlc->tty_for_write_work = tty;
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tty->disc_data = n_hdlc;
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tty->receive_room = 65536;
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/* change tty_io write() to not split large writes into 8K chunks */
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set_bit(TTY_NO_WRITE_SPLIT, &tty->flags);
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/* flush receive data from driver */
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tty_driver_flush_buffer(tty);
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return 0;
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} /* end of n_tty_hdlc_open() */
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/**
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* n_hdlc_send_frames - send frames on pending send buffer list
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* @n_hdlc: pointer to ldisc instance data
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* @tty: pointer to tty instance data
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*
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* Send frames on pending send buffer list until the driver does not accept a
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* frame (busy) this function is called after adding a frame to the send buffer
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* list and by the tty wakeup callback.
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*/
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static void n_hdlc_send_frames(struct n_hdlc *n_hdlc, struct tty_struct *tty)
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{
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register int actual;
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unsigned long flags;
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struct n_hdlc_buf *tbuf;
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check_again:
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spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
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if (n_hdlc->tbusy) {
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n_hdlc->woke_up = true;
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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return;
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}
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n_hdlc->tbusy = true;
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n_hdlc->woke_up = false;
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
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while (tbuf) {
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pr_debug("sending frame %p, count=%d\n", tbuf, tbuf->count);
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/* Send the next block of data to device */
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set_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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actual = tty->ops->write(tty, tbuf->buf, tbuf->count);
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/* rollback was possible and has been done */
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if (actual == -ERESTARTSYS) {
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n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf);
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break;
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}
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/* if transmit error, throw frame away by */
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/* pretending it was accepted by driver */
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if (actual < 0)
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actual = tbuf->count;
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if (actual == tbuf->count) {
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pr_debug("frame %p completed\n", tbuf);
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/* free current transmit buffer */
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n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, tbuf);
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/* wait up sleeping writers */
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wake_up_interruptible(&tty->write_wait);
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/* get next pending transmit buffer */
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tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
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} else {
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pr_debug("frame %p pending\n", tbuf);
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/*
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* the buffer was not accepted by driver,
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* return it back into tx queue
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*/
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n_hdlc_buf_return(&n_hdlc->tx_buf_list, tbuf);
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break;
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}
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}
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if (!tbuf)
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clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
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/* Clear the re-entry flag */
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spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
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n_hdlc->tbusy = false;
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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if (n_hdlc->woke_up)
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goto check_again;
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} /* end of n_hdlc_send_frames() */
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/**
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* n_hdlc_tty_write_work - Asynchronous callback for transmit wakeup
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* @work: pointer to work_struct
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*
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* Called when low level device driver can accept more send data.
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*/
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static void n_hdlc_tty_write_work(struct work_struct *work)
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{
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struct n_hdlc *n_hdlc = container_of(work, struct n_hdlc, write_work);
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struct tty_struct *tty = n_hdlc->tty_for_write_work;
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n_hdlc_send_frames(n_hdlc, tty);
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} /* end of n_hdlc_tty_write_work() */
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/**
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* n_hdlc_tty_wakeup - Callback for transmit wakeup
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* @tty: pointer to associated tty instance data
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*
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* Called when low level device driver can accept more send data.
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*/
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static void n_hdlc_tty_wakeup(struct tty_struct *tty)
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{
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struct n_hdlc *n_hdlc = tty->disc_data;
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schedule_work(&n_hdlc->write_work);
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} /* end of n_hdlc_tty_wakeup() */
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/**
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* n_hdlc_tty_receive - Called by tty driver when receive data is available
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* @tty: pointer to tty instance data
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* @data: pointer to received data
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* @flags: pointer to flags for data
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* @count: count of received data in bytes
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*
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* Called by tty low level driver when receive data is available. Data is
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* interpreted as one HDLC frame.
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*/
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static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *data,
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const char *flags, int count)
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{
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register struct n_hdlc *n_hdlc = tty->disc_data;
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register struct n_hdlc_buf *buf;
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pr_debug("%s() called count=%d\n", __func__, count);
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if (count > maxframe) {
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pr_debug("rx count>maxframesize, data discarded\n");
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return;
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}
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/* get a free HDLC buffer */
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buf = n_hdlc_buf_get(&n_hdlc->rx_free_buf_list);
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if (!buf) {
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/*
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* no buffers in free list, attempt to allocate another rx
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* buffer unless the maximum count has been reached
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*/
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if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT)
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buf = kmalloc(struct_size(buf, buf, maxframe),
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GFP_ATOMIC);
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}
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if (!buf) {
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pr_debug("no more rx buffers, data discarded\n");
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return;
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}
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/* copy received data to HDLC buffer */
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memcpy(buf->buf, data, count);
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buf->count = count;
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|
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/* add HDLC buffer to list of received frames */
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n_hdlc_buf_put(&n_hdlc->rx_buf_list, buf);
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|
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/* wake up any blocked reads and perform async signalling */
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wake_up_interruptible(&tty->read_wait);
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if (tty->fasync != NULL)
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kill_fasync(&tty->fasync, SIGIO, POLL_IN);
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|
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} /* end of n_hdlc_tty_receive() */
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|
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/**
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* n_hdlc_tty_read - Called to retrieve one frame of data (if available)
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* @tty: pointer to tty instance data
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* @file: pointer to open file object
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* @kbuf: pointer to returned data buffer
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* @nr: size of returned data buffer
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* @cookie: stored rbuf from previous run
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* @offset: offset into the data buffer
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*
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* Returns the number of bytes returned or error code.
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*/
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static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
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__u8 *kbuf, size_t nr,
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void **cookie, unsigned long offset)
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{
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struct n_hdlc *n_hdlc = tty->disc_data;
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int ret = 0;
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struct n_hdlc_buf *rbuf;
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DECLARE_WAITQUEUE(wait, current);
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/* Is this a repeated call for an rbuf we already found earlier? */
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rbuf = *cookie;
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if (rbuf)
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goto have_rbuf;
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add_wait_queue(&tty->read_wait, &wait);
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for (;;) {
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if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
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ret = -EIO;
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break;
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}
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if (tty_hung_up_p(file))
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break;
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set_current_state(TASK_INTERRUPTIBLE);
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rbuf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
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if (rbuf)
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break;
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|
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/* no data */
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if (tty_io_nonblock(tty, file)) {
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ret = -EAGAIN;
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break;
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}
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|
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schedule();
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|
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if (signal_pending(current)) {
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ret = -EINTR;
|
|
break;
|
|
}
|
|
}
|
|
|
|
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
|
|
*
|
|
* 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)
|
|
{
|
|
struct n_hdlc *n_hdlc = tty->disc_data;
|
|
int error = 0;
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
struct n_hdlc_buf *tbuf;
|
|
|
|
pr_debug("%s() called count=%zd\n", __func__, count);
|
|
|
|
/* verify frame size */
|
|
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 (tty_io_nonblock(tty, file)) {
|
|
error = -EAGAIN;
|
|
break;
|
|
}
|
|
schedule();
|
|
|
|
if (signal_pending(current)) {
|
|
error = -EINTR;
|
|
break;
|
|
}
|
|
}
|
|
|
|
__set_current_state(TASK_RUNNING);
|
|
remove_wait_queue(&tty->write_wait, &wait);
|
|
|
|
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);
|
|
}
|
|
|
|
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
|
|
* @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, unsigned int cmd,
|
|
unsigned long arg)
|
|
{
|
|
struct n_hdlc *n_hdlc = tty->disc_data;
|
|
int error = 0;
|
|
int count;
|
|
unsigned long flags;
|
|
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);
|
|
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;
|
|
spin_unlock_irqrestore(&n_hdlc->rx_buf_list.spinlock, flags);
|
|
error = put_user(count, (int __user *)arg);
|
|
break;
|
|
|
|
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);
|
|
buf = list_first_entry_or_null(&n_hdlc->tx_buf_list.list,
|
|
struct n_hdlc_buf, list_item);
|
|
if (buf)
|
|
count += buf->count;
|
|
spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
|
|
error = put_user(count, (int __user *)arg);
|
|
break;
|
|
|
|
case TCFLSH:
|
|
switch (arg) {
|
|
case TCIOFLUSH:
|
|
case TCOFLUSH:
|
|
flush_tx_queue(tty);
|
|
}
|
|
fallthrough; /* to default */
|
|
|
|
default:
|
|
error = n_tty_ioctl_helper(tty, cmd, arg);
|
|
break;
|
|
}
|
|
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
|
|
* @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 __poll_t n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
|
|
poll_table *wait)
|
|
{
|
|
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
|
|
*
|
|
* Returns a pointer to newly created structure if success, otherwise %NULL
|
|
*/
|
|
static struct n_hdlc *n_hdlc_alloc(void)
|
|
{
|
|
struct n_hdlc *n_hdlc = kzalloc(sizeof(*n_hdlc), GFP_KERNEL);
|
|
|
|
if (!n_hdlc)
|
|
return NULL;
|
|
|
|
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_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_return(struct n_hdlc_buf_list *buf_list,
|
|
struct n_hdlc_buf *buf)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&buf_list->spinlock, flags);
|
|
|
|
list_add(&buf->list_item, &buf_list->list);
|
|
buf_list->count++;
|
|
|
|
spin_unlock_irqrestore(&buf_list->spinlock, flags);
|
|
}
|
|
|
|
/**
|
|
* n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
|
|
* @buf_list: pointer to buffer list
|
|
* @buf: pointer to buffer
|
|
*/
|
|
static void n_hdlc_buf_put(struct n_hdlc_buf_list *buf_list,
|
|
struct n_hdlc_buf *buf)
|
|
{
|
|
unsigned long flags;
|
|
|
|
spin_lock_irqsave(&buf_list->spinlock, flags);
|
|
|
|
list_add_tail(&buf->list_item, &buf_list->list);
|
|
buf_list->count++;
|
|
|
|
spin_unlock_irqrestore(&buf_list->spinlock, flags);
|
|
} /* end of n_hdlc_buf_put() */
|
|
|
|
/**
|
|
* n_hdlc_buf_get - remove and return an HDLC buffer from 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 *buf_list)
|
|
{
|
|
unsigned long flags;
|
|
struct n_hdlc_buf *buf;
|
|
|
|
spin_lock_irqsave(&buf_list->spinlock, flags);
|
|
|
|
buf = list_first_entry_or_null(&buf_list->list,
|
|
struct n_hdlc_buf, list_item);
|
|
if (buf) {
|
|
list_del(&buf->list_item);
|
|
buf_list->count--;
|
|
}
|
|
|
|
spin_unlock_irqrestore(&buf_list->spinlock, flags);
|
|
return buf;
|
|
} /* end of n_hdlc_buf_get() */
|
|
|
|
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 */
|
|
maxframe = clamp(maxframe, 4096, MAX_HDLC_FRAME_SIZE);
|
|
|
|
status = tty_register_ldisc(&n_hdlc_ldisc);
|
|
if (!status)
|
|
pr_info("N_HDLC line discipline registered with maxframe=%d\n",
|
|
maxframe);
|
|
else
|
|
pr_err("N_HDLC: error registering line discipline: %d\n",
|
|
status);
|
|
|
|
return status;
|
|
|
|
} /* end of init_module() */
|
|
|
|
static void __exit n_hdlc_exit(void)
|
|
{
|
|
tty_unregister_ldisc(&n_hdlc_ldisc);
|
|
}
|
|
|
|
module_init(n_hdlc_init);
|
|
module_exit(n_hdlc_exit);
|
|
|
|
MODULE_LICENSE("GPL");
|
|
MODULE_AUTHOR("Paul Fulghum paulkf@microgate.com");
|
|
module_param(maxframe, int, 0);
|
|
MODULE_ALIAS_LDISC(N_HDLC);
|