[PATCH] uml: Add throttling to console driver
This patch adds support for throttling and unthrottling input when the tty
driver can't handle it.
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index 851a7c8..b8e3e80 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -36,8 +36,9 @@
{
struct line *line = arg;
- chan_interrupt(&line->chan_list, &line->task, line->tty,
- line->driver->read_irq);
+ if(!line->throttled)
+ chan_interrupt(&line->chan_list, &line->task, line->tty,
+ line->driver->read_irq);
}
/* Returns the free space inside the ring buffer of this line.
@@ -340,6 +341,30 @@
return ret;
}
+void line_throttle(struct tty_struct *tty)
+{
+ struct line *line = tty->driver_data;
+
+ deactivate_chan(&line->chan_list, line->driver->read_irq);
+ line->throttled = 1;
+}
+
+void line_unthrottle(struct tty_struct *tty)
+{
+ struct line *line = tty->driver_data;
+
+ line->throttled = 0;
+ chan_interrupt(&line->chan_list, &line->task, tty,
+ line->driver->read_irq);
+
+ /* Maybe there is enough stuff pending that calling the interrupt
+ * throttles us again. In this case, line->throttled will be 1
+ * again and we shouldn't turn the interrupt back on.
+ */
+ if(!line->throttled)
+ reactivate_chan(&line->chan_list, line->driver->read_irq);
+}
+
static irqreturn_t line_write_interrupt(int irq, void *data,
struct pt_regs *unused)
{