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path: root/drivers/char/tty_io.c
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Diffstat (limited to 'drivers/char/tty_io.c')
-rw-r--r--drivers/char/tty_io.c127
1 files changed, 96 insertions, 31 deletions
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index a96f26a63fa2..9c867cf6de64 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -369,25 +369,54 @@ static void tty_buffer_free(struct tty_struct *tty, struct tty_buffer *b)
}
/**
- * tty_buffer_flush - flush full tty buffers
+ * __tty_buffer_flush - flush full tty buffers
* @tty: tty to flush
*
- * flush all the buffers containing receive data
+ * flush all the buffers containing receive data. Caller must
+ * hold the buffer lock and must have ensured no parallel flush to
+ * ldisc is running.
*
- * Locking: none
+ * Locking: Caller must hold tty->buf.lock
*/
-static void tty_buffer_flush(struct tty_struct *tty)
+static void __tty_buffer_flush(struct tty_struct *tty)
{
struct tty_buffer *thead;
- unsigned long flags;
- spin_lock_irqsave(&tty->buf.lock, flags);
while((thead = tty->buf.head) != NULL) {
tty->buf.head = thead->next;
tty_buffer_free(tty, thead);
}
tty->buf.tail = NULL;
+}
+
+/**
+ * tty_buffer_flush - flush full tty buffers
+ * @tty: tty to flush
+ *
+ * flush all the buffers containing receive data. If the buffer is
+ * being processed by flush_to_ldisc then we defer the processing
+ * to that function
+ *
+ * Locking: none
+ */
+
+static void tty_buffer_flush(struct tty_struct *tty)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&tty->buf.lock, flags);
+
+ /* If the data is being pushed to the tty layer then we can't
+ process it here. Instead set a flag and the flush_to_ldisc
+ path will process the flush request before it exits */
+ if (test_bit(TTY_FLUSHING, &tty->flags)) {
+ set_bit(TTY_FLUSHPENDING, &tty->flags);
+ spin_unlock_irqrestore(&tty->buf.lock, flags);
+ wait_event(tty->read_wait,
+ test_bit(TTY_FLUSHPENDING, &tty->flags) == 0);
+ return;
+ } else
+ __tty_buffer_flush(tty);
spin_unlock_irqrestore(&tty->buf.lock, flags);
}
@@ -1503,6 +1532,15 @@ int tty_hung_up_p(struct file * filp)
EXPORT_SYMBOL(tty_hung_up_p);
+/**
+ * is_tty - checker whether file is a TTY
+ */
+int is_tty(struct file *filp)
+{
+ return filp->f_op->read == tty_read
+ || filp->f_op->read == hung_up_tty_read;
+}
+
static void session_clear_tty(struct pid *session)
{
struct task_struct *p;
@@ -1726,6 +1764,23 @@ static ssize_t tty_read(struct file * file, char __user * buf, size_t count,
return i;
}
+void tty_write_unlock(struct tty_struct *tty)
+{
+ mutex_unlock(&tty->atomic_write_lock);
+ wake_up_interruptible(&tty->write_wait);
+}
+
+int tty_write_lock(struct tty_struct *tty, int ndelay)
+{
+ if (!mutex_trylock(&tty->atomic_write_lock)) {
+ if (ndelay)
+ return -EAGAIN;
+ if (mutex_lock_interruptible(&tty->atomic_write_lock))
+ return -ERESTARTSYS;
+ }
+ return 0;
+}
+
/*
* Split writes up in sane blocksizes to avoid
* denial-of-service type attacks
@@ -1737,13 +1792,12 @@ static inline ssize_t do_tty_write(
const char __user *buf,
size_t count)
{
- ssize_t ret = 0, written = 0;
+ ssize_t ret, written = 0;
unsigned int chunk;
- /* FIXME: O_NDELAY ... */
- if (mutex_lock_interruptible(&tty->atomic_write_lock)) {
- return -ERESTARTSYS;
- }
+ ret = tty_write_lock(tty, file->f_flags & O_NDELAY);
+ if (ret < 0)
+ return ret;
/*
* We chunk up writes into a temporary buffer. This
@@ -1776,8 +1830,8 @@ static inline ssize_t do_tty_write(
buf = kmalloc(chunk, GFP_KERNEL);
if (!buf) {
- mutex_unlock(&tty->atomic_write_lock);
- return -ENOMEM;
+ ret = -ENOMEM;
+ goto out;
}
kfree(tty->write_buf);
tty->write_cnt = chunk;
@@ -1812,7 +1866,8 @@ static inline ssize_t do_tty_write(
inode->i_mtime = current_fs_time(inode->i_sb);
ret = written;
}
- mutex_unlock(&tty->atomic_write_lock);
+out:
+ tty_write_unlock(tty);
return ret;
}
@@ -2008,19 +2063,16 @@ static int init_dev(struct tty_driver *driver, int idx,
}
if (!*tp_loc) {
- tp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
- GFP_KERNEL);
+ tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!tp)
goto free_mem_out;
*tp = driver->init_termios;
}
if (!*ltp_loc) {
- ltp = (struct ktermios *) kmalloc(sizeof(struct ktermios),
- GFP_KERNEL);
+ ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!ltp)
goto free_mem_out;
- memset(ltp, 0, sizeof(struct ktermios));
}
if (driver->type == TTY_DRIVER_TYPE_PTY) {
@@ -2041,19 +2093,16 @@ static int init_dev(struct tty_driver *driver, int idx,
}
if (!*o_tp_loc) {
- o_tp = (struct ktermios *)
- kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+ o_tp = kmalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!o_tp)
goto free_mem_out;
*o_tp = driver->other->init_termios;
}
if (!*o_ltp_loc) {
- o_ltp = (struct ktermios *)
- kmalloc(sizeof(struct ktermios), GFP_KERNEL);
+ o_ltp = kzalloc(sizeof(struct ktermios), GFP_KERNEL);
if (!o_ltp)
goto free_mem_out;
- memset(o_ltp, 0, sizeof(struct ktermios));
}
/*
@@ -2660,6 +2709,7 @@ got_driver:
__proc_set_tty(current, tty);
spin_unlock_irq(&current->sighand->siglock);
mutex_unlock(&tty_mutex);
+ tty_audit_opening();
return 0;
}
@@ -2722,8 +2772,10 @@ static int ptmx_open(struct inode * inode, struct file * filp)
check_tty_count(tty, "tty_open");
retval = ptm_driver->open(tty, filp);
- if (!retval)
+ if (!retval) {
+ tty_audit_opening();
return 0;
+ }
out1:
release_dev(filp);
return retval;
@@ -3163,14 +3215,13 @@ static int tiocsetd(struct tty_struct *tty, int __user *p)
static int send_break(struct tty_struct *tty, unsigned int duration)
{
- if (mutex_lock_interruptible(&tty->atomic_write_lock))
+ if (tty_write_lock(tty, 0) < 0)
return -EINTR;
tty->driver->break_ctl(tty, -1);
- if (!signal_pending(current)) {
+ if (!signal_pending(current))
msleep_interruptible(duration);
- }
tty->driver->break_ctl(tty, 0);
- mutex_unlock(&tty->atomic_write_lock);
+ tty_write_unlock(tty);
if (signal_pending(current))
return -EINTR;
return 0;
@@ -3570,6 +3621,7 @@ static void flush_to_ldisc(struct work_struct *work)
return;
spin_lock_irqsave(&tty->buf.lock, flags);
+ set_bit(TTY_FLUSHING, &tty->flags); /* So we know a flush is running */
head = tty->buf.head;
if (head != NULL) {
tty->buf.head = NULL;
@@ -3583,6 +3635,11 @@ static void flush_to_ldisc(struct work_struct *work)
tty_buffer_free(tty, tbuf);
continue;
}
+ /* Ldisc or user is trying to flush the buffers
+ we are feeding to the ldisc, stop feeding the
+ line discipline as we want to empty the queue */
+ if (test_bit(TTY_FLUSHPENDING, &tty->flags))
+ break;
if (!tty->receive_room) {
schedule_delayed_work(&tty->buf.work, 1);
break;
@@ -3596,8 +3653,17 @@ static void flush_to_ldisc(struct work_struct *work)
disc->receive_buf(tty, char_buf, flag_buf, count);
spin_lock_irqsave(&tty->buf.lock, flags);
}
+ /* Restore the queue head */
tty->buf.head = head;
}
+ /* We may have a deferred request to flush the input buffer,
+ if so pull the chain under the lock and empty the queue */
+ if (test_bit(TTY_FLUSHPENDING, &tty->flags)) {
+ __tty_buffer_flush(tty);
+ clear_bit(TTY_FLUSHPENDING, &tty->flags);
+ wake_up(&tty->read_wait);
+ }
+ clear_bit(TTY_FLUSHING, &tty->flags);
spin_unlock_irqrestore(&tty->buf.lock, flags);
tty_ldisc_deref(disc);
@@ -3739,9 +3805,8 @@ struct tty_driver *alloc_tty_driver(int lines)
{
struct tty_driver *driver;
- driver = kmalloc(sizeof(struct tty_driver), GFP_KERNEL);
+ driver = kzalloc(sizeof(struct tty_driver), GFP_KERNEL);
if (driver) {
- memset(driver, 0, sizeof(struct tty_driver));
driver->magic = TTY_DRIVER_MAGIC;
driver->num = lines;
/* later we'll move allocation of tables here */
generated by cgit v1.2.3 (git 2.0.4) at 2024-05-23 08:50:17 +0000