[PATCH] uml: console locking commentary and code cleanup

Remove the last vestiges of devfs from console registration.  Change the name
of the function, plus remove a couple of unused fields from the line_driver
structure.

struct lines is no longer needed, all traces of it are gone.

The only way that I can see to mark a structure as being almost-const is to
individually const the fields.  This is the case for the line_driver
structure, which has only one modifiable field - a list_head in a
sub-structure.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Cc: Paolo 'Blaisorblade' Giarrusso <blaisorblade@yahoo.it>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

4 files changed, 31 insertions, 45 deletions

diff --git a/arch/um/drivers/line.c b/arch/um/drivers/line.c
index e620ed46ed3f..433e572fb196 100644
--- a/arch/um/drivers/line.c
+++ b/arch/um/drivers/line.c
@@ -707,10 +707,9 @@ int line_remove(struct line *lines, unsigned int num, int n, char **error_out)
         return err;
 }
 
-struct tty_driver *line_register_devfs(struct lines *set,
-                                       struct line_driver *line_driver,
-                                       const struct tty_operations *ops,
-                                       struct line *lines, int nlines)
+struct tty_driver *register_lines(struct line_driver *line_driver,
+                                  const struct tty_operations *ops,
+                                  struct line *lines, int nlines)
 {
         int i;
         struct tty_driver *driver = alloc_tty_driver(nlines);
diff --git a/arch/um/drivers/ssl.c b/arch/um/drivers/ssl.c
index 475de52783e4..fc22b9bd9153 100644
--- a/arch/um/drivers/ssl.c
+++ b/arch/um/drivers/ssl.c
@@ -51,6 +51,8 @@ static int ssl_config(char *str, char **error_out);
 static int ssl_get_config(char *dev, char *str, int size, char **error_out);
 static int ssl_remove(int n, char **error_out);
 
+
+/* Const, except for .mc.list */
 static struct line_driver driver = {
         .name                   = "UML serial line",
         .device_name            = "ttyS",
@@ -62,8 +64,6 @@ static struct line_driver driver = {
         .read_irq_name          = "ssl",
         .write_irq              = SSL_WRITE_IRQ,
         .write_irq_name         = "ssl-write",
-        .symlink_from           = "serial",
-        .symlink_to             = "tts",
         .mc  = {
                 .list           = LIST_HEAD_INIT(driver.mc.list),
                 .name           = "ssl",
@@ -74,14 +74,12 @@ static struct line_driver driver = {
         },
 };
 
-/* The array is initialized by line_init, which is an initcall.  The 
- * individual elements are protected by individual semaphores.
+/* The array is initialized by line_init, at initcall time.  The
+ * elements are locked individually as needed.
  */
 static struct line serial_lines[NR_PORTS] =
         { [0 ... NR_PORTS - 1] = LINE_INIT(CONFIG_SSL_CHAN, &driver) };
 
-static struct lines lines = LINES_INIT(NR_PORTS);
-
 static int ssl_config(char *str, char **error_out)
 {
         return line_config(serial_lines, ARRAY_SIZE(serial_lines), str, &opts,
@@ -175,6 +173,7 @@ static int ssl_console_setup(struct console *co, char *options)
         return console_open_chan(line, co);
 }
 
+/* No locking for register_console call - relies on single-threaded initcalls */
 static struct console ssl_cons = {
         .name           = "ttyS",
         .write          = ssl_console_write,
@@ -190,9 +189,8 @@ static int ssl_init(void)
 
         printk(KERN_INFO "Initializing software serial port version %d\n",
                ssl_version);
-        ssl_driver = line_register_devfs(&lines, &driver, &ssl_ops,
-                                         serial_lines,
-                                         ARRAY_SIZE(serial_lines));
+        ssl_driver = register_lines(&driver, &ssl_ops, serial_lines,
+                                    ARRAY_SIZE(serial_lines));
 
         lines_init(serial_lines, ARRAY_SIZE(serial_lines), &opts);
 
diff --git a/arch/um/drivers/stdio_console.c b/arch/um/drivers/stdio_console.c
index a83c42c263b3..8dccdd193d94 100644
--- a/arch/um/drivers/stdio_console.c
+++ b/arch/um/drivers/stdio_console.c
@@ -55,6 +55,8 @@ static int con_config(char *str, char **error_out);
 static int con_get_config(char *dev, char *str, int size, char **error_out);
 static int con_remove(int n, char **con_remove);
 
+
+/* Const, except for .mc.list */
 static struct line_driver driver = {
         .name                   = "UML console",
         .device_name            = "tty",
@@ -66,8 +68,6 @@ static struct line_driver driver = {
         .read_irq_name          = "console",
         .write_irq              = CONSOLE_WRITE_IRQ,
         .write_irq_name         = "console-write",
-        .symlink_from           = "ttys",
-        .symlink_to             = "vc",
         .mc  = {
                 .name           = "con",
                 .config         = con_config,
@@ -77,10 +77,8 @@ static struct line_driver driver = {
         },
 };
 
-static struct lines console_lines = LINES_INIT(MAX_TTYS);
-
-/* The array is initialized by line_init, which is an initcall.  The 
- * individual elements are protected by individual semaphores.
+/* The array is initialized by line_init, at initcall time.  The
+ * elements are locked individually as needed.
  */
 static struct line vts[MAX_TTYS] = { LINE_INIT(CONFIG_CON_ZERO_CHAN, &driver),
                                      [ 1 ... MAX_TTYS - 1 ] =
@@ -148,6 +146,7 @@ static int uml_console_setup(struct console *co, char *options)
         return console_open_chan(line, co);
 }
 
+/* No locking for register_console call - relies on single-threaded initcalls */
 static struct console stdiocons = {
         .name           = "tty",
         .write          = uml_console_write,
@@ -155,16 +154,14 @@ static struct console stdiocons = {
         .setup          = uml_console_setup,
         .flags          = CON_PRINTBUFFER,
         .index          = -1,
-        .data           = &vts,
 };
 
 int stdio_init(void)
 {
         char *new_title;
 
-        console_driver = line_register_devfs(&console_lines, &driver,
-                                             &console_ops, vts,
-                                             ARRAY_SIZE(vts));
+        console_driver = register_lines(&driver, &console_ops, vts,
+                                        ARRAY_SIZE(vts));
         if (console_driver == NULL)
                 return -1;
         printk(KERN_INFO "Initialized stdio console driver\n");
diff --git a/arch/um/include/line.h b/arch/um/include/line.h
index a2486b4cc9fe..3477a858eaa9 100644
--- a/arch/um/include/line.h
+++ b/arch/um/include/line.h
@@ -15,19 +15,18 @@
 #include "chan_user.h"
 #include "mconsole_kern.h"
 
+/* There's only one modifiable field in this - .mc.list */
 struct line_driver {
-        char *name;
-        char *device_name;
-        short major;
-        short minor_start;
-        short type;
-        short subtype;
-        int read_irq;
-        char *read_irq_name;
-        int write_irq;
-        char *write_irq_name;
-        char *symlink_from;
-        char *symlink_to;
+        const char *name;
+        const char *device_name;
+        const short major;
+        const short minor_start;
+        const short type;
+        const short subtype;
+        const int read_irq;
+        const char *read_irq_name;
+        const int write_irq;
+        const char *write_irq_name;
         struct mc_device mc;
 };
 
@@ -67,12 +66,6 @@ struct line {
           .lock =       SPIN_LOCK_UNLOCKED, \
           .driver =     d }
 
-struct lines {
-        int num;
-};
-
-#define LINES_INIT(n) {  .num = n }
-
 extern void line_close(struct tty_struct *tty, struct file * filp);
 extern int line_open(struct line *lines, struct tty_struct *tty);
 extern int line_setup(struct line *lines, unsigned int sizeof_lines,
@@ -94,10 +87,9 @@ extern char *add_xterm_umid(char *base);
 extern int line_setup_irq(int fd, int input, int output, struct line *line,
                           void *data);
 extern void line_close_chan(struct line *line);
-extern struct tty_driver * line_register_devfs(struct lines *set,
-                                               struct line_driver *line_driver,
-                                               const struct tty_operations *driver,
-                                               struct line *lines, int nlines);
+extern struct tty_driver *register_lines(struct line_driver *line_driver,
+                                         const struct tty_operations *driver,
+                                         struct line *lines, int nlines);
 extern void lines_init(struct line *lines, int nlines, struct chan_opts *opts);
 extern void close_lines(struct line *lines, int nlines);