[PATCH] uml: redo console locking

Fix some console locking problems (including scheduling in atomic) and various
reorderings and cleanup in that code.  Not yet ready for 2.6.12 probably.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/drivers/chan_kern.c

@@ -22,7 +22,7 @@
 #ifdef CONFIG_NOCONFIG_CHAN
 static void *not_configged_init(char *str, int device, struct chan_opts *opts)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 	return(NULL);
 }
@@ -30,27 +30,27 @@ static void *not_configged_init(char *str, int device, struct chan_opts *opts)
 static int not_configged_open(int input, int output, int primary, void *data,
 			      char **dev_out)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 	return(-ENODEV);
 }
 
 static void not_configged_close(int fd, void *data)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 }
 
 static int not_configged_read(int fd, char *c_out, void *data)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 	return(-EIO);
 }
 
 static int not_configged_write(int fd, const char *buf, int len, void *data)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 	return(-EIO);
 }
@@ -58,7 +58,7 @@ static int not_configged_write(int fd, const char *buf, int len, void *data)
 static int not_configged_console_write(int fd, const char *buf, int len,
 				       void *data)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 	return(-EIO);
 }
@@ -66,14 +66,14 @@ static int not_configged_console_write(int fd, const char *buf, int len,
 static int not_configged_window_size(int fd, void *data, unsigned short *rows,
 				     unsigned short *cols)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 	return(-ENODEV);
 }
 
 static void not_configged_free(void *data)
 {
-	printk(KERN_ERR "Using a channel type which is configured out of "
+	printf(KERN_ERR "Using a channel type which is configured out of "
 	       "UML\n");
 }
 

arch/um/drivers/ssl.c

@@ -107,11 +107,6 @@ int ssl_open(struct tty_struct *tty, struct file *filp)
 }
 
 #if 0
-static int ssl_chars_in_buffer(struct tty_struct *tty)
-{
-	return(0);
-}
-
 static void ssl_flush_buffer(struct tty_struct *tty)
 {
 	return;
@@ -149,11 +144,11 @@ static struct tty_operations ssl_ops = {
 	.put_char 		= line_put_char,
 	.write_room		= line_write_room,
 	.chars_in_buffer 	= line_chars_in_buffer,
+	.flush_buffer 		= line_flush_buffer,
+	.flush_chars 		= line_flush_chars,
 	.set_termios 		= line_set_termios,
 	.ioctl 	 		= line_ioctl,
 #if 0
-	.flush_chars 		= ssl_flush_chars,
-	.flush_buffer 		= ssl_flush_buffer,
 	.throttle 		= ssl_throttle,
 	.unthrottle 		= ssl_unthrottle,
 	.stop 	 		= ssl_stop,
@@ -171,10 +166,11 @@ static void ssl_console_write(struct console *c, const char *string,
 			      unsigned len)
 {
 	struct line *line = &serial_lines[c->index];
+	unsigned long flags;
 
-	down(&line->sem);
+	spin_lock_irqsave(&line->lock, flags);
 	console_write_chan(&line->chan_list, string, len);
-	up(&line->sem);
+	spin_unlock_irqrestore(&line->lock, flags);
 }
 
 static struct tty_driver *ssl_console_device(struct console *c, int *index)
@@ -238,14 +234,3 @@ static int ssl_chan_setup(char *str)
 
 __setup("ssl", ssl_chan_setup);
 __channel_help(ssl_chan_setup, "ssl");
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */

arch/um/drivers/stdio_console.c

@@ -116,8 +116,11 @@ static struct tty_operations console_ops = {
 	.open 	 		= con_open,
 	.close 	 		= line_close,
 	.write 	 		= line_write,
+	.put_char 		= line_put_char,
  	.write_room		= line_write_room,
 	.chars_in_buffer 	= line_chars_in_buffer,
+	.flush_buffer 		= line_flush_buffer,
+	.flush_chars 		= line_flush_chars,
 	.set_termios 		= line_set_termios,
 	.ioctl 	 		= line_ioctl,
 };
@@ -126,10 +129,11 @@ static void uml_console_write(struct console *console, const char *string,
 			  unsigned len)
 {
 	struct line *line = &vts[console->index];
+	unsigned long flags;
 
-	down(&line->sem);
+	spin_lock_irqsave(&line->lock, flags);
 	console_write_chan(&line->chan_list, string, len);
-	up(&line->sem);
+	spin_unlock_irqrestore(&line->lock, flags);
 }
 
 static struct tty_driver *uml_console_device(struct console *c, int *index)
@@ -192,14 +196,3 @@ static int console_chan_setup(char *str)
 }
 __setup("con", console_chan_setup);
 __channel_help(console_chan_setup, "con");
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */

arch/um/include/line.h

@@ -10,7 +10,7 @@
 #include "linux/workqueue.h"
 #include "linux/tty.h"
 #include "linux/interrupt.h"
-#include "asm/semaphore.h"
+#include "linux/spinlock.h"
 #include "chan_user.h"
 #include "mconsole_kern.h"
 
@@ -37,10 +37,18 @@ struct line {
 	struct list_head chan_list;
 	int valid;
 	int count;
-	struct semaphore sem;
+	/*This lock is actually, mostly, local to*/
+	spinlock_t lock;
+
+	/* Yes, this is a real circular buffer.
+	 * XXX: And this should become a struct kfifo!
+	 *
+	 * buffer points to a buffer allocated on demand, of length
+	 * LINE_BUFSIZE, head to the start of the ring, tail to the end.*/
 	char *buffer;
 	char *head;
 	char *tail;
+
 	int sigio;
 	struct work_struct task;
 	struct line_driver *driver;
@@ -52,7 +60,6 @@ struct line {
 	  init_pri :	INIT_STATIC, \
 	  chan_list : 	{ }, \
 	  valid :	1, \
-	  sem : 	{ }, \
 	  buffer :	NULL, \
 	  head :	NULL, \
 	  tail :	NULL, \
@@ -69,15 +76,18 @@ struct lines {
 extern void line_close(struct tty_struct *tty, struct file * filp);
 extern int line_open(struct line *lines, struct tty_struct *tty, 
 		     struct chan_opts *opts);
-extern int line_setup(struct line *lines, int num, char *init, 
+extern int line_setup(struct line *lines, unsigned int sizeof_lines, char *init,
 		      int all_allowed);
 extern int line_write(struct tty_struct *tty, const unsigned char *buf, int len);
 extern void line_put_char(struct tty_struct *tty, unsigned char ch);
 extern void line_set_termios(struct tty_struct *tty, struct termios * old);
 extern int line_chars_in_buffer(struct tty_struct *tty);
+extern void line_flush_buffer(struct tty_struct *tty);
+extern void line_flush_chars(struct tty_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 char *add_xterm_umid(char *base);
 extern int line_setup_irq(int fd, int input, int output, struct tty_struct *tty);
 extern void line_close_chan(struct line *line);
@@ -89,20 +99,10 @@ extern struct tty_driver * line_register_devfs(struct lines *set,
 				int nlines);
 extern void lines_init(struct line *lines, int nlines);
 extern void close_lines(struct line *lines, int nlines);
-extern int line_config(struct line *lines, int num, char *str);
-extern int line_remove(struct line *lines, int num, char *str);
-extern int line_get_config(char *dev, struct line *lines, int num, char *str, 
+
+extern int line_config(struct line *lines, unsigned int sizeof_lines, char *str);
+extern int line_remove(struct line *lines, unsigned int sizeof_lines, char *str);
+extern int line_get_config(char *dev, struct line *lines, unsigned int sizeof_lines, char *str,
 			   int size, char **error_out);
 
 #endif
-
-/*
- * Overrides for Emacs so that we follow Linus's tabbing style.
- * Emacs will notice this stuff at the end of the file and automatically
- * adjust the settings for this buffer only.  This must remain at the end
- * of the file.
- * ---------------------------------------------------------------------------
- * Local variables:
- * c-file-style: "linux"
- * End:
- */