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Subject[PATCH 2/6] TTY: um/line, use tty from tty_port
Date
From: Jiri Slaby <jslaby@suse.cz>

This means switching to the tty refcounted model so that we will not
race with interrupts.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: user-mode-linux-devel@lists.sourceforge.net
Signed-off-by: Richard Weinberger <richard@nod.at>
---
arch/um/drivers/chan_kern.c | 4 +++-
arch/um/drivers/line.c | 25 ++++++++++++++++++-------
arch/um/drivers/line.h | 1 -
3 files changed, 21 insertions(+), 9 deletions(-)
diff --git a/arch/um/drivers/chan_kern.c b/arch/um/drivers/chan_kern.c
index 45e248c..87eebfe 100644
--- a/arch/um/drivers/chan_kern.c
+++ b/arch/um/drivers/chan_kern.c
@@ -150,9 +150,11 @@ void chan_enable_winch(struct chan *chan, struct tty_struct *tty)
static void line_timer_cb(struct work_struct *work)
{
struct line *line = container_of(work, struct line, task.work);
+ struct tty_struct *tty = tty_port_tty_get(&line->port);

if (!line->throttled)
- chan_interrupt(line, line->tty, line->driver->read_irq);
+ chan_interrupt(line, tty, line->driver->read_irq);
+ tty_kref_put(tty);
}

int enable_chan(struct line *line)
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 482a7bd..fb6e4ea 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -19,9 +19,11 @@ static irqreturn_t line_interrupt(int irq, void *data)
{
struct chan *chan = data;
struct line *line = chan->line;
+ struct tty_struct *tty = tty_port_tty_get(&line->port);

if (line)
- chan_interrupt(line, line->tty, irq);
+ chan_interrupt(line, tty, irq);
+ tty_kref_put(tty);
return IRQ_HANDLED;
}

@@ -333,7 +335,7 @@ static irqreturn_t line_write_interrupt(int irq, void *data)
{
struct chan *chan = data;
struct line *line = chan->line;
- struct tty_struct *tty = line->tty;
+ struct tty_struct *tty;
int err;

/*
@@ -352,10 +354,13 @@ static irqreturn_t line_write_interrupt(int irq, void *data)
}
spin_unlock(&line->lock);

+ tty = tty_port_tty_get(&line->port);
if (tty == NULL)
return IRQ_NONE;

tty_wakeup(tty);
+ tty_kref_put(tty);
+
return IRQ_HANDLED;
}

@@ -409,7 +414,7 @@ int line_open(struct line *lines, struct tty_struct *tty)

BUG_ON(tty->driver_data);
tty->driver_data = line;
- line->tty = tty;
+ tty_port_tty_set(&line->port, tty);

err = enable_chan(line);
if (err) /* line_close() will be called by our caller */
@@ -449,7 +454,7 @@ void line_close(struct tty_struct *tty, struct file * filp)
if (--line->port.count)
goto out_unlock;

- line->tty = NULL;
+ tty_port_tty_set(&line->port, NULL);
tty->driver_data = NULL;

if (line->sigio) {
@@ -610,9 +615,15 @@ int line_get_config(char *name, struct line *lines, unsigned int num, char *str,
mutex_lock(&line->count_lock);
if (!line->valid)
CONFIG_CHUNK(str, size, n, "none", 1);
- else if (line->tty == NULL)
- CONFIG_CHUNK(str, size, n, line->init_str, 1);
- else n = chan_config_string(line, str, size, error_out);
+ else {
+ struct tty_struct *tty = tty_port_tty_get(&line->port);
+ if (tty == NULL) {
+ CONFIG_CHUNK(str, size, n, line->init_str, 1);
+ } else {
+ n = chan_config_string(line, str, size, error_out);
+ tty_kref_put(tty);
+ }
+ }
mutex_unlock(&line->count_lock);

return n;
diff --git a/arch/um/drivers/line.h b/arch/um/drivers/line.h
index 0e06a1f..5b3d4fb 100644
--- a/arch/um/drivers/line.h
+++ b/arch/um/drivers/line.h
@@ -33,7 +33,6 @@ struct line_driver {

struct line {
struct tty_port port;
- struct tty_struct *tty;
struct mutex count_lock;
int valid;

--
1.7.7.3


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