[PATCH 1/3] Provide console_device()

Russell King
2004-06-14T14:13:13Z

[This patch series has also been separately sent to the architecture
maintainers]

Add console_device() to return the console tty driver structure and the
index. Acquire the console lock while scanning the list of console
drivers to protect us against console driver list manipulations.

Signed-off-by: Russell King <rmk@arm.linux.org.uk>

diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x *.orig -x *.rej orig/drivers/char/tty_io.c linux/drivers/char/tty_io.c
--- orig/drivers/char/tty_io.c Wed Jun 9 00:51:02 2004
+++ linux/drivers/char/tty_io.c Mon Jun 14 10:55:28 2004
@@ -1344,13 +1344,8 @@ retry_open:
}
#endif
if (device == MKDEV(TTYAUX_MAJOR,1)) {
- struct console *c = console_drivers;
- for (c = console_drivers; c; c = c->next) {
- if (!c->device)
- continue;
- driver = c->device(c, &index);
- if (!driver)
- continue;
+ driver = console_device(&index);
+ if (driver) {
/* Don't let /dev/console block */
filp->f_flags |= O_NONBLOCK;
noctty = 1;
diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x *.orig -x *.rej orig/kernel/printk.c linux/kernel/printk.c
--- orig/kernel/printk.c Sun May 30 10:33:00 2004
+++ linux/kernel/printk.c Mon Jun 14 10:56:18 2004
@@ -683,6 +683,23 @@ void console_unblank(void)
}
EXPORT_SYMBOL(console_unblank);

+struct tty_driver *console_device(int *index)
+{
+ struct console *c;
+ struct tty_driver *driver = NULL;
+
+ acquire_console_sem();
+ for (c = console_drivers; c != NULL; c = c->next) {
+ if (!c->device)
+ continue;
+ driver = c->device(c, index);
+ if (driver)
+ break;
+ }
+ release_console_sem();
+ return driver;
+}
+
/*
* The console driver calls this routine during kernel initialization
* to register the console printing procedure with printk() and to
diff -up -x BitKeeper -x ChangeSet -x SCCS -x _xlk -x *.orig -x *.rej orig/include/linux/console.h linux/include/linux/console.h
--- orig/include/linux/console.h Mon May 24 11:26:21 2004
+++ linux/include/linux/console.h Mon Jun 14 10:55:28 2004
@@ -104,6 +104,7 @@ extern void acquire_console_sem(void);
extern void release_console_sem(void);
extern void console_conditional_schedule(void);
extern void console_unblank(void);
+extern struct tty_driver *console_device(int *);
extern int is_console_locked(void);

/* Some debug stub to catch some of the obvious races in the VT code */