[PATCH -next 0/3] more tty closing fixes

[PATCH -next 0/3] more tty closing fixes

[Peter Hurley]

Hi Greg,

These 3 patches are stragglers from the old tty closing series.
I'm still working on eliminating ASYNC_CLOSING and the improvements to
opening in O_NONBLOCK mode.

Regards,

Peter Hurley (3):
  tty: Move tty hung up check from port->lock critical section
  tty: Convert tty->closing to int
  tty: Flush tty buffers after hardware shutdown

 drivers/tty/tty_port.c | 7 +++----
 include/linux/tty.h    | 2 +-
 2 files changed, 4 insertions(+), 5 deletions(-)

-- 
2.1.3

[PATCH -next 1/3] tty: Move tty hung up check from port->lock critical section

[Peter Hurley]

The port->lock does not protect the filp->f_op field; move
the tty_hung_up_p() test outside the port->lock critical section
in tty_port_close_start().

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/tty_port.c | 6 ++----
 1 file changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 1b93357..3b641d1 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -473,12 +473,10 @@ int tty_port_close_start(struct tty_port *port,
 {
 	unsigned long flags;
 
-	spin_lock_irqsave(&port->lock, flags);
-	if (tty_hung_up_p(filp)) {
-		spin_unlock_irqrestore(&port->lock, flags);
+	if (tty_hung_up_p(filp))
 		return 0;
-	}
 
+	spin_lock_irqsave(&port->lock, flags);
 	if (tty->count == 1 && port->count != 1) {
 		printk(KERN_WARNING
 		    "tty_port_close_start: tty->count = 1 port count = %d.\n",
-- 
2.1.3

[PATCH -next 2/3] tty: Convert tty->closing to int

[Peter Hurley]

tty->closing is a bitfield member; prevent corruption from non-atomic
update by assigning a unique memory location.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 include/linux/tty.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/tty.h b/include/linux/tty.h
index c52a689..7d66ae5 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -284,7 +284,7 @@ struct tty_struct {
 
 #define N_TTY_BUF_SIZE 4096
 
-	unsigned char closing:1;
+	int closing;
 	unsigned char *write_buf;
 	int write_cnt;
 	/* If the tty has a pending do_SAK, queue it here - akpm */
-- 
2.1.3

[PATCH -next 3/3] tty: Flush tty buffers after hardware shutdown

[Peter Hurley]

The line discipline buffer and the tty buffers must be flushed again
after hardware shutdown; otherwise, a brief window exists between the
ldisc flush in tty_port_close_start() and the subsequent
tty_port_shutdown(), during which more data could be received into the
tty buffers. A racing open might then be able to receive data from the
previous session.

Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
---
 drivers/tty/tty_port.c | 1 +
 1 file changed, 1 insertion(+)

diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 3b641d1..4d9abaa 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -520,6 +520,7 @@ void tty_port_close_end(struct tty_port *port, struct tty_struct *tty)
 {
 	unsigned long flags;
 
+	tty_ldisc_flush(tty);
 	tty->closing = 0;
 
 	spin_lock_irqsave(&port->lock, flags);
-- 
2.1.3