forked from Minki/linux
0f40fbbcc3
OpenSSH expects the (non-blocking) read() of pty master to return EAGAIN only if it has received all of the slave-side output after it has received SIGCHLD. This used to work on pre-3.12 kernels. This fix effectively forces non-blocking read() and poll() to block for parallel i/o to complete for all ttys. It also unwinds these changes: 1)f8747d4a46
tty: Fix pty master read() after slave closes 2)52bce7f8d4
pty, n_tty: Simplify input processing on final close 3)1a48632ffe
pty: Fix input race when closing Inspired by analysis and patch from Marc Aurele La France <tsi@tuyoix.net> Reported-by: Volth <openssh@volth.com> Reported-by: Marc Aurele La France <tsi@tuyoix.net> BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=52 BugLink: https://bugzilla.mindrot.org/show_bug.cgi?id=2492 Signed-off-by: Brian Bloniarz <brian.bloniarz@gmail.com> Reviewed-by: Peter Hurley <peter@hurleysoftware.com> Cc: stable <stable@vger.kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
989 lines
27 KiB
C
989 lines
27 KiB
C
/* 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 code is released under the GNU General Public License (GPL)
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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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#define HDLC_MAGIC 0x239e
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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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#undef VERSION
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#define VERSION(major,minor,patch) (((((major)<<8)+(minor))<<8)+(patch))
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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 <asm/termios.h>
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#include <asm/uaccess.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 n_hdlc_buf *link;
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int count;
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char buf[1];
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};
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#define N_HDLC_BUF_SIZE (sizeof(struct n_hdlc_buf) + maxframe)
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struct n_hdlc_buf_list {
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struct n_hdlc_buf *head;
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struct n_hdlc_buf *tail;
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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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* @magic - magic value for structure
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* @flags - miscellaneous control flags
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* @tty - ptr to TTY structure
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* @backup_tty - TTY to use if tty gets closed
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* @tbusy - reentrancy flag for tx wakeup code
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* @woke_up - FIXME: describe this field
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* @tbuf - currently transmitting tx buffer
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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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int magic;
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__u32 flags;
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struct tty_struct *tty;
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struct tty_struct *backup_tty;
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int tbusy;
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int woke_up;
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struct n_hdlc_buf *tbuf;
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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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};
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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_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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/* debug level can be set by insmod for debugging purposes */
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#define DEBUG_LEVEL_INFO 1
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static int debuglevel;
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/* max frame size for memory allocations */
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static int maxframe = 4096;
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/* TTY callbacks */
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static ssize_t n_hdlc_tty_read(struct tty_struct *tty, struct file *file,
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__u8 __user *buf, size_t nr);
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static ssize_t n_hdlc_tty_write(struct tty_struct *tty, struct file *file,
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const unsigned char *buf, size_t nr);
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static int n_hdlc_tty_ioctl(struct tty_struct *tty, struct file *file,
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unsigned int cmd, unsigned long arg);
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static unsigned int n_hdlc_tty_poll(struct tty_struct *tty, struct file *filp,
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poll_table *wait);
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static int n_hdlc_tty_open(struct tty_struct *tty);
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static void n_hdlc_tty_close(struct tty_struct *tty);
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static void n_hdlc_tty_receive(struct tty_struct *tty, const __u8 *cp,
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char *fp, int count);
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static void n_hdlc_tty_wakeup(struct tty_struct *tty);
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#define bset(p,b) ((p)[(b) >> 5] |= (1 << ((b) & 0x1f)))
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#define tty2n_hdlc(tty) ((struct n_hdlc *) ((tty)->disc_data))
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#define n_hdlc2tty(n_hdlc) ((n_hdlc)->tty)
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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 = tty2n_hdlc(tty);
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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 = tty2n_hdlc(tty);
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struct n_hdlc_buf *buf;
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unsigned long flags;
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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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spin_lock_irqsave(&n_hdlc->tx_buf_list.spinlock, flags);
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if (n_hdlc->tbuf) {
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n_hdlc_buf_put(&n_hdlc->tx_free_buf_list, n_hdlc->tbuf);
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n_hdlc->tbuf = NULL;
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}
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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}
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static struct tty_ldisc_ops n_hdlc_ldisc = {
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.owner = THIS_MODULE,
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.magic = TTY_LDISC_MAGIC,
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.name = "hdlc",
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.open = n_hdlc_tty_open,
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.close = n_hdlc_tty_close,
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.read = n_hdlc_tty_read,
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.write = n_hdlc_tty_write,
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.ioctl = n_hdlc_tty_ioctl,
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.poll = n_hdlc_tty_poll,
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.receive_buf = n_hdlc_tty_receive,
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.write_wakeup = n_hdlc_tty_wakeup,
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.flush_buffer = flush_rx_queue,
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};
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/**
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* n_hdlc_release - release an n_hdlc per device line discipline info structure
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* @n_hdlc - per device line discipline info structure
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*/
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static void n_hdlc_release(struct n_hdlc *n_hdlc)
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{
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struct tty_struct *tty = n_hdlc2tty (n_hdlc);
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struct n_hdlc_buf *buf;
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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)n_hdlc_release() called\n",__FILE__,__LINE__);
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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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if (tty->disc_data == n_hdlc)
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tty->disc_data = NULL; /* Break the tty->n_hdlc link */
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/* Release transmit and receive buffers */
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for(;;) {
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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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kfree(buf);
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} else
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break;
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}
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for(;;) {
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buf = n_hdlc_buf_get(&n_hdlc->tx_free_buf_list);
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if (buf) {
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kfree(buf);
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} else
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break;
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}
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for(;;) {
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buf = n_hdlc_buf_get(&n_hdlc->rx_buf_list);
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if (buf) {
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kfree(buf);
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} else
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break;
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}
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for(;;) {
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buf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
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if (buf) {
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kfree(buf);
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} else
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break;
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}
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kfree(n_hdlc->tbuf);
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kfree(n_hdlc);
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} /* end of n_hdlc_release() */
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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 = tty2n_hdlc (tty);
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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)n_hdlc_tty_close() called\n",__FILE__,__LINE__);
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if (n_hdlc != NULL) {
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if (n_hdlc->magic != HDLC_MAGIC) {
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printk (KERN_WARNING"n_hdlc: trying to close unopened tty!\n");
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return;
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}
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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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if (tty == n_hdlc->backup_tty)
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n_hdlc->backup_tty = NULL;
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if (tty != n_hdlc->tty)
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return;
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if (n_hdlc->backup_tty) {
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n_hdlc->tty = n_hdlc->backup_tty;
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} else {
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n_hdlc_release (n_hdlc);
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}
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}
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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)n_hdlc_tty_close() success\n",__FILE__,__LINE__);
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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 = tty2n_hdlc (tty);
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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)n_hdlc_tty_open() called (device=%s)\n",
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__FILE__,__LINE__,
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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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printk (KERN_ERR"n_hdlc_tty_open:tty already associated!\n" );
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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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printk (KERN_ERR "n_hdlc_alloc failed\n");
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return -ENFILE;
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}
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tty->disc_data = n_hdlc;
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n_hdlc->tty = tty;
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tty->receive_room = 65536;
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#if defined(TTY_NO_WRITE_SPLIT)
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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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#endif
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/* flush receive data from driver */
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tty_driver_flush_buffer(tty);
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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)n_hdlc_tty_open() success\n",__FILE__,__LINE__);
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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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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)n_hdlc_send_frames() called\n",__FILE__,__LINE__);
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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 = 1;
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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 = 1;
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n_hdlc->woke_up = 0;
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spin_unlock_irqrestore(&n_hdlc->tx_buf_list.spinlock, flags);
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/* get current transmit buffer or get new transmit */
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/* buffer from list of pending transmit buffers */
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tbuf = n_hdlc->tbuf;
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if (!tbuf)
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tbuf = n_hdlc_buf_get(&n_hdlc->tx_buf_list);
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while (tbuf) {
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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)sending frame %p, count=%d\n",
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__FILE__,__LINE__,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->tbuf = 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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if (debuglevel >= DEBUG_LEVEL_INFO)
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printk("%s(%d)frame %p completed\n",
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__FILE__,__LINE__,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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/* this tx buffer is done */
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n_hdlc->tbuf = NULL;
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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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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;
|
|
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__);
|
|
|
|
} /* end of n_hdlc_send_frames() */
|
|
|
|
/**
|
|
* 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 = tty2n_hdlc(tty);
|
|
|
|
if (debuglevel >= DEBUG_LEVEL_INFO)
|
|
printk("%s(%d)n_hdlc_tty_wakeup() called\n",__FILE__,__LINE__);
|
|
|
|
if (!n_hdlc)
|
|
return;
|
|
|
|
if (tty != n_hdlc->tty) {
|
|
clear_bit(TTY_DO_WRITE_WAKEUP, &tty->flags);
|
|
return;
|
|
}
|
|
|
|
n_hdlc_send_frames (n_hdlc, tty);
|
|
|
|
} /* 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
|
|
*
|
|
* 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)
|
|
{
|
|
register struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
|
|
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__);
|
|
return;
|
|
}
|
|
|
|
/* 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 */
|
|
if (n_hdlc->rx_buf_list.count < MAX_RX_BUF_COUNT)
|
|
buf = kmalloc(N_HDLC_BUF_SIZE, GFP_ATOMIC);
|
|
}
|
|
|
|
if (!buf) {
|
|
if (debuglevel >= DEBUG_LEVEL_INFO)
|
|
printk("%s(%d) no more rx buffers, data discarded\n",
|
|
__FILE__,__LINE__);
|
|
return;
|
|
}
|
|
|
|
/* copy received data to HDLC buffer */
|
|
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);
|
|
|
|
} /* 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
|
|
*
|
|
* 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)
|
|
{
|
|
struct n_hdlc *n_hdlc = tty2n_hdlc(tty);
|
|
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;
|
|
}
|
|
|
|
add_wait_queue(&tty->read_wait, &wait);
|
|
|
|
for (;;) {
|
|
if (test_bit(TTY_OTHER_CLOSED, &tty->flags)) {
|
|
ret = -EIO;
|
|
break;
|
|
}
|
|
if (tty_hung_up_p(file))
|
|
break;
|
|
|
|
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);
|
|
break;
|
|
}
|
|
|
|
/* no data */
|
|
if (file->f_flags & O_NONBLOCK) {
|
|
ret = -EAGAIN;
|
|
break;
|
|
}
|
|
|
|
schedule();
|
|
|
|
if (signal_pending(current)) {
|
|
ret = -EINTR;
|
|
break;
|
|
}
|
|
}
|
|
|
|
remove_wait_queue(&tty->read_wait, &wait);
|
|
__set_current_state(TASK_RUNNING);
|
|
|
|
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 = tty2n_hdlc (tty);
|
|
int error = 0;
|
|
DECLARE_WAITQUEUE(wait, current);
|
|
struct n_hdlc_buf *tbuf;
|
|
|
|
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;
|
|
|
|
/* 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 );
|
|
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) {
|
|
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;
|
|
}
|
|
}
|
|
|
|
__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
|
|
* @file - pointer to open file object for device
|
|
* @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)
|
|
{
|
|
struct n_hdlc *n_hdlc = tty2n_hdlc (tty);
|
|
int error = 0;
|
|
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;
|
|
|
|
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;
|
|
|
|
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;
|
|
|
|
case TCFLSH:
|
|
switch (arg) {
|
|
case TCIOFLUSH:
|
|
case TCOFLUSH:
|
|
flush_tx_queue(tty);
|
|
}
|
|
/* fall through to default */
|
|
|
|
default:
|
|
error = n_tty_ioctl_helper(tty, file, 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
|
|
* @poll_table - 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,
|
|
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 */
|
|
}
|
|
return mask;
|
|
} /* end of n_hdlc_tty_poll() */
|
|
|
|
/**
|
|
* 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_buf *buf;
|
|
int i;
|
|
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);
|
|
|
|
/* 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;
|
|
|
|
return n_hdlc;
|
|
|
|
} /* end of n_hdlc_alloc() */
|
|
|
|
/**
|
|
* n_hdlc_buf_put - add specified HDLC buffer to tail of specified list
|
|
* @list - pointer to buffer list
|
|
* @buf - pointer to buffer
|
|
*/
|
|
static void n_hdlc_buf_put(struct n_hdlc_buf_list *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);
|
|
|
|
} /* end of n_hdlc_buf_put() */
|
|
|
|
/**
|
|
* n_hdlc_buf_get - remove and return an HDLC buffer from list
|
|
* @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)
|
|
{
|
|
unsigned long flags;
|
|
struct n_hdlc_buf *buf;
|
|
spin_lock_irqsave(&list->spinlock,flags);
|
|
|
|
buf = list->head;
|
|
if (buf) {
|
|
list->head = buf->link;
|
|
(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 int __init n_hdlc_init(void)
|
|
{
|
|
int status;
|
|
|
|
/* range check maxframe arg */
|
|
if (maxframe < 4096)
|
|
maxframe = 4096;
|
|
else if (maxframe > 65535)
|
|
maxframe = 65535;
|
|
|
|
printk(hdlc_banner, maxframe);
|
|
|
|
status = tty_register_ldisc(N_HDLC, &n_hdlc_ldisc);
|
|
if (!status)
|
|
printk(hdlc_register_ok);
|
|
else
|
|
printk(hdlc_register_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";
|
|
|
|
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);
|
|
}
|
|
|
|
module_init(n_hdlc_init);
|
|
module_exit(n_hdlc_exit);
|
|
|
|
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);
|