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-rw-r--r--MAINTAINERS3
-rw-r--r--drivers/char/pty.c57
-rw-r--r--drivers/char/tty_io.c2
-rw-r--r--drivers/char/tty_ioctl.c5
-rw-r--r--drivers/char/tty_ldisc.c3
-rw-r--r--drivers/serial/atmel_serial.c8
-rw-r--r--drivers/serial/imx.c12
7 files changed, 64 insertions, 26 deletions
diff --git a/MAINTAINERS b/MAINTAINERS
index 2cb7566..09f6b3e 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -157,9 +157,10 @@ S: Maintained
F: drivers/net/r8169.c
8250/16?50 (AND CLONE UARTS) SERIAL DRIVER
+P: Alan Cox
+M: alan@lxorguk.ukuu.org.uk
L: linux-serial@vger.kernel.org
W: http://serial.sourceforge.net
-M: alan@lxorguk.ukuu.org.uk
S: Odd Fixes
F: drivers/serial/8250*
F: include/linux/serial_8250.h
diff --git a/drivers/char/pty.c b/drivers/char/pty.c
index 3910ce1..daebe1b 100644
--- a/drivers/char/pty.c
+++ b/drivers/char/pty.c
@@ -95,23 +95,34 @@ static void pty_unthrottle(struct tty_struct *tty)
* a count.
*
* FIXME: Our pty_write method is called with our ldisc lock held but
- * not our partners. We can't just take the other one blindly without
- * risking deadlocks.
+ * not our partners. We can't just wait on the other one blindly without
+ * risking deadlocks. At some point when everything has settled down we need
+ * to look into making pty_write at least able to sleep over an ldisc change.
+ *
+ * The return on no ldisc is a bit counter intuitive but the logic works
+ * like this. During an ldisc change the other end will flush its buffers. We
+ * thus return the full length which is identical to the case where we had
+ * proper locking and happened to queue the bytes just before the flush during
+ * the ldisc change.
*/
static int pty_write(struct tty_struct *tty, const unsigned char *buf,
int count)
{
struct tty_struct *to = tty->link;
- int c;
+ struct tty_ldisc *ld;
+ int c = count;
- if (!to || !to->ldisc || tty->stopped)
+ if (!to || tty->stopped)
return 0;
-
- c = to->receive_room;
- if (c > count)
- c = count;
- to->ldisc->ops->receive_buf(to, buf, NULL, c);
-
+ ld = tty_ldisc_ref(to);
+
+ if (ld) {
+ c = to->receive_room;
+ if (c > count)
+ c = count;
+ ld->ops->receive_buf(to, buf, NULL, c);
+ tty_ldisc_deref(ld);
+ }
return c;
}
@@ -145,14 +156,23 @@ static int pty_write_room(struct tty_struct *tty)
static int pty_chars_in_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
- int count;
+ struct tty_ldisc *ld;
+ int count = 0;
/* We should get the line discipline lock for "tty->link" */
- if (!to || !to->ldisc || !to->ldisc->ops->chars_in_buffer)
+ if (!to)
+ return 0;
+ /* We cannot take a sleeping reference here without deadlocking with
+ an ldisc change - but it doesn't really matter */
+ ld = tty_ldisc_ref(to);
+ if (ld == NULL)
return 0;
/* The ldisc must report 0 if no characters available to be read */
- count = to->ldisc->ops->chars_in_buffer(to);
+ if (ld->ops->chars_in_buffer)
+ count = ld->ops->chars_in_buffer(to);
+
+ tty_ldisc_deref(ld);
if (tty->driver->subtype == PTY_TYPE_SLAVE)
return count;
@@ -182,12 +202,19 @@ static void pty_flush_buffer(struct tty_struct *tty)
{
struct tty_struct *to = tty->link;
unsigned long flags;
+ struct tty_ldisc *ld;
+
+ if (!to)
+ return;
+ ld = tty_ldisc_ref(to);
- if (!to || !to->ldisc)
+ /* The other end is changing discipline */
+ if (!ld)
return;
- if (to->ldisc->ops->flush_buffer)
+ if (ld->ops->flush_buffer)
to->ldisc->ops->flush_buffer(to);
+ tty_ldisc_deref(ld);
if (to->packet) {
spin_lock_irqsave(&tty->ctrl_lock, flags);
diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 939e198..a3afa0c 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1263,7 +1263,9 @@ static int tty_reopen(struct tty_struct *tty)
tty->count++;
tty->driver = driver; /* N.B. why do this every time?? */
+ mutex_lock(&tty->ldisc_mutex);
WARN_ON(!test_bit(TTY_LDISC, &tty->flags));
+ mutex_unlock(&tty->ldisc_mutex);
return 0;
}
diff --git a/drivers/char/tty_ioctl.c b/drivers/char/tty_ioctl.c
index 8116bb1c..b24f6c6 100644
--- a/drivers/char/tty_ioctl.c
+++ b/drivers/char/tty_ioctl.c
@@ -947,7 +947,6 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
void __user *p = (void __user *)arg;
int ret = 0;
struct ktermios kterm;
- struct termiox ktermx;
if (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
tty->driver->subtype == PTY_TYPE_MASTER)
@@ -1049,7 +1048,8 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
return ret;
#endif
#ifdef TCGETX
- case TCGETX:
+ case TCGETX: {
+ struct termiox ktermx;
if (real_tty->termiox == NULL)
return -EINVAL;
mutex_lock(&real_tty->termios_mutex);
@@ -1058,6 +1058,7 @@ int tty_mode_ioctl(struct tty_struct *tty, struct file *file,
if (copy_to_user(p, &ktermx, sizeof(struct termiox)))
ret = -EFAULT;
return ret;
+ }
case TCSETX:
return set_termiox(real_tty, p, 0);
case TCSETXW:
diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 94b3e06..a19e935 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -207,6 +207,7 @@ static void tty_ldisc_put(struct tty_ldisc *ld)
ldo->refcount--;
module_put(ldo->owner);
spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+ WARN_ON(ld->refcount);
kfree(ld);
}
@@ -793,6 +794,8 @@ void tty_ldisc_hangup(struct tty_struct *tty)
/* Avoid racing set_ldisc */
mutex_lock(&tty->ldisc_mutex);
/* Switch back to N_TTY */
+ tty_ldisc_halt(tty);
+ tty_ldisc_wait_idle(tty);
tty_ldisc_reinit(tty);
/* At this point we have a closed ldisc and we want to
reopen it. We could defer this to the next open but
diff --git a/drivers/serial/atmel_serial.c b/drivers/serial/atmel_serial.c
index b3497d7..338b15c 100644
--- a/drivers/serial/atmel_serial.c
+++ b/drivers/serial/atmel_serial.c
@@ -1104,11 +1104,13 @@ static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
/* update the per-port timeout */
uart_update_timeout(port, termios->c_cflag, baud);
- /* save/disable interrupts and drain transmitter */
+ /*
+ * save/disable interrupts. The tty layer will ensure that the
+ * transmitter is empty if requested by the caller, so there's
+ * no need to wait for it here.
+ */
imr = UART_GET_IMR(port);
UART_PUT_IDR(port, -1);
- while (!(UART_GET_CSR(port) & ATMEL_US_TXEMPTY))
- cpu_relax();
/* disable receiver and transmitter */
UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);
diff --git a/drivers/serial/imx.c b/drivers/serial/imx.c
index 285b414..5d7b58f 100644
--- a/drivers/serial/imx.c
+++ b/drivers/serial/imx.c
@@ -924,11 +924,13 @@ imx_set_termios(struct uart_port *port, struct ktermios *termios,
rational_best_approximation(16 * div * baud, sport->port.uartclk,
1 << 16, 1 << 16, &num, &denom);
- tdiv64 = sport->port.uartclk;
- tdiv64 *= num;
- do_div(tdiv64, denom * 16 * div);
- tty_encode_baud_rate(sport->port.info->port.tty,
- (speed_t)tdiv64, (speed_t)tdiv64);
+ if (port->info && port->info->port.tty) {
+ tdiv64 = sport->port.uartclk;
+ tdiv64 *= num;
+ do_div(tdiv64, denom * 16 * div);
+ tty_encode_baud_rate(sport->port.info->port.tty,
+ (speed_t)tdiv64, (speed_t)tdiv64);
+ }
num -= 1;
denom -= 1;
generated by cgit v1.1 at 2024-11-02 05:48:48 +0000