From: Jeff Dike <jdike@addtoit.com>
To: akpm@osdl.org
Cc: linux-kernel@vger.kernel.org,
user-mode-linux-devel@lists.sourceforge.net
Subject: [uml-devel] [PATCH 12/12] UML - Add throttling to console driver
Date: Tue, 03 Jan 2006 19:37:50 -0500 [thread overview]
Message-ID: <200601040037.k040bo1L012582@ccure.user-mode-linux.org> (raw)
This patch adds support for throttling and unthrottling input when
the tty driver can't handle it.
Index: linux-2.6.15/arch/um/drivers/ssl.c
===================================================================
--- linux-2.6.15.orig/arch/um/drivers/ssl.c 2006-01-03 17:32:45.000000000 -0500
+++ linux-2.6.15/arch/um/drivers/ssl.c 2006-01-03 17:35:00.000000000 -0500
@@ -109,16 +109,6 @@ static void ssl_flush_buffer(struct tty_
return;
}
-static void ssl_throttle(struct tty_struct * tty)
-{
- printk(KERN_ERR "Someone should implement ssl_throttle\n");
-}
-
-static void ssl_unthrottle(struct tty_struct * tty)
-{
- printk(KERN_ERR "Someone should implement ssl_unthrottle\n");
-}
-
static void ssl_stop(struct tty_struct *tty)
{
printk(KERN_ERR "Someone should implement ssl_stop\n");
@@ -145,9 +135,9 @@ static struct tty_operations ssl_ops = {
.flush_chars = line_flush_chars,
.set_termios = line_set_termios,
.ioctl = line_ioctl,
+ .throttle = line_throttle,
+ .unthrottle = line_unthrottle,
#if 0
- .throttle = ssl_throttle,
- .unthrottle = ssl_unthrottle,
.stop = ssl_stop,
.start = ssl_start,
.hangup = ssl_hangup,
Index: linux-2.6.15/arch/um/drivers/stdio_console.c
===================================================================
--- linux-2.6.15.orig/arch/um/drivers/stdio_console.c 2006-01-03 17:32:45.000000000 -0500
+++ linux-2.6.15/arch/um/drivers/stdio_console.c 2006-01-03 17:35:00.000000000 -0500
@@ -122,6 +122,8 @@ static struct tty_operations console_ops
.flush_chars = line_flush_chars,
.set_termios = line_set_termios,
.ioctl = line_ioctl,
+ .throttle = line_throttle,
+ .unthrottle = line_unthrottle,
};
static void uml_console_write(struct console *console, const char *string,
Index: linux-2.6.15/arch/um/include/line.h
===================================================================
--- linux-2.6.15.orig/arch/um/include/line.h 2006-01-03 17:33:23.000000000 -0500
+++ linux-2.6.15/arch/um/include/line.h 2006-01-03 17:35:00.000000000 -0500
@@ -38,6 +38,7 @@ struct line {
struct list_head chan_list;
int valid;
int count;
+ int throttled;
/*This lock is actually, mostly, local to*/
spinlock_t lock;
@@ -60,6 +61,7 @@ struct line {
{ init_str : str, \
init_pri : INIT_STATIC, \
valid : 1, \
+ throttled : 0, \
lock : SPIN_LOCK_UNLOCKED, \
buffer : NULL, \
head : NULL, \
@@ -88,6 +90,8 @@ extern void line_flush_chars(struct tty_
extern int line_write_room(struct tty_struct *tty);
extern int line_ioctl(struct tty_struct *tty, struct file * file,
unsigned int cmd, unsigned long arg);
+extern void line_throttle(struct tty_struct *tty);
+extern void line_unthrottle(struct tty_struct *tty);
extern char *add_xterm_umid(char *base);
extern int line_setup_irq(int fd, int input, int output, struct line *line,
Index: linux-2.6.15/arch/um/drivers/line.c
===================================================================
--- linux-2.6.15.orig/arch/um/drivers/line.c 2006-01-03 17:33:23.000000000 -0500
+++ linux-2.6.15/arch/um/drivers/line.c 2006-01-03 17:35:00.000000000 -0500
@@ -36,8 +36,9 @@ static void line_timer_cb(void *arg)
{
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 @@ int line_ioctl(struct tty_struct *tty, s
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)
{
Index: linux-2.6.15/arch/um/drivers/chan_kern.c
===================================================================
--- linux-2.6.15.orig/arch/um/drivers/chan_kern.c 2006-01-03 17:34:49.000000000 -0500
+++ linux-2.6.15/arch/um/drivers/chan_kern.c 2006-01-03 17:35:00.000000000 -0500
@@ -312,6 +312,32 @@ void close_chan(struct list_head *chans,
}
}
+void deactivate_chan(struct list_head *chans, int irq)
+{
+ struct list_head *ele;
+
+ struct chan *chan;
+ list_for_each(ele, chans) {
+ chan = list_entry(ele, struct chan, list);
+
+ if(chan->enabled && chan->input)
+ deactivate_fd(chan->fd, irq);
+ }
+}
+
+void reactivate_chan(struct list_head *chans, int irq)
+{
+ struct list_head *ele;
+ struct chan *chan;
+
+ list_for_each(ele, chans) {
+ chan = list_entry(ele, struct chan, list);
+
+ if(chan->enabled && chan->input)
+ reactivate_fd(chan->fd, irq);
+ }
+}
+
int write_chan(struct list_head *chans, const char *buf, int len,
int write_irq)
{
Index: linux-2.6.15/arch/um/include/chan_kern.h
===================================================================
--- linux-2.6.15.orig/arch/um/include/chan_kern.h 2006-01-03 17:33:23.000000000 -0500
+++ linux-2.6.15/arch/um/include/chan_kern.h 2006-01-03 17:35:00.000000000 -0500
@@ -38,6 +38,8 @@ extern int console_write_chan(struct lis
int len);
extern int console_open_chan(struct line *line, struct console *co,
struct chan_opts *opts);
+extern void deactivate_chan(struct list_head *chans, int irq);
+extern void reactivate_chan(struct list_head *chans, int irq);
extern void chan_enable_winch(struct list_head *chans, struct tty_struct *tty);
extern void enable_chan(struct line *line);
extern void close_chan(struct list_head *chans, int delay_free_irq);
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