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Diffstat (limited to 'kernel')
-rw-r--r--kernel/printk.c146
1 files changed, 92 insertions, 54 deletions
diff --git a/kernel/printk.c b/kernel/printk.c
index b4d97b54c1e..41fe6099553 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -37,6 +37,12 @@
#include <asm/uaccess.h>
/*
+ * for_each_console() allows you to iterate on each console
+ */
+#define for_each_console(con) \
+ for (con = console_drivers; con != NULL; con = con->next)
+
+/*
* Architectures can override it:
*/
void asmlinkage __attribute__((weak)) early_printk(const char *fmt, ...)
@@ -412,7 +418,7 @@ static void __call_console_drivers(unsigned start, unsigned end)
{
struct console *con;
- for (con = console_drivers; con; con = con->next) {
+ for_each_console(con) {
if ((con->flags & CON_ENABLED) && con->write &&
(cpu_online(smp_processor_id()) ||
(con->flags & CON_ANYTIME)))
@@ -544,7 +550,7 @@ static int have_callable_console(void)
{
struct console *con;
- for (con = console_drivers; con; con = con->next)
+ for_each_console(con)
if (con->flags & CON_ANYTIME)
return 1;
@@ -1082,7 +1088,7 @@ void console_unblank(void)
console_locked = 1;
console_may_schedule = 0;
- for (c = console_drivers; c != NULL; c = c->next)
+ for_each_console(c)
if ((c->flags & CON_ENABLED) && c->unblank)
c->unblank();
release_console_sem();
@@ -1097,7 +1103,7 @@ struct tty_driver *console_device(int *index)
struct tty_driver *driver = NULL;
acquire_console_sem();
- for (c = console_drivers; c != NULL; c = c->next) {
+ for_each_console(c) {
if (!c->device)
continue;
driver = c->device(c, index);
@@ -1134,25 +1140,49 @@ EXPORT_SYMBOL(console_start);
* to register the console printing procedure with printk() and to
* print any messages that were printed by the kernel before the
* console driver was initialized.
+ *
+ * This can happen pretty early during the boot process (because of
+ * early_printk) - sometimes before setup_arch() completes - be careful
+ * of what kernel features are used - they may not be initialised yet.
+ *
+ * There are two types of consoles - bootconsoles (early_printk) and
+ * "real" consoles (everything which is not a bootconsole) which are
+ * handled differently.
+ * - Any number of bootconsoles can be registered at any time.
+ * - As soon as a "real" console is registered, all bootconsoles
+ * will be unregistered automatically.
+ * - Once a "real" console is registered, any attempt to register a
+ * bootconsoles will be rejected
*/
-void register_console(struct console *console)
+void register_console(struct console *newcon)
{
int i;
unsigned long flags;
- struct console *bootconsole = NULL;
+ struct console *bcon = NULL;
- if (console_drivers) {
- if (console->flags & CON_BOOT)
- return;
- if (console_drivers->flags & CON_BOOT)
- bootconsole = console_drivers;
+ /*
+ * before we register a new CON_BOOT console, make sure we don't
+ * already have a valid console
+ */
+ if (console_drivers && newcon->flags & CON_BOOT) {
+ /* find the last or real console */
+ for_each_console(bcon) {
+ if (!(bcon->flags & CON_BOOT)) {
+ printk(KERN_INFO "Too late to register bootconsole %s%d\n",
+ newcon->name, newcon->index);
+ return;
+ }
+ }
}
- if (preferred_console < 0 || bootconsole || !console_drivers)
+ if (console_drivers && console_drivers->flags & CON_BOOT)
+ bcon = console_drivers;
+
+ if (preferred_console < 0 || bcon || !console_drivers)
preferred_console = selected_console;
- if (console->early_setup)
- console->early_setup();
+ if (newcon->early_setup)
+ newcon->early_setup();
/*
* See if we want to use this console driver. If we
@@ -1160,13 +1190,13 @@ void register_console(struct console *console)
* that registers here.
*/
if (preferred_console < 0) {
- if (console->index < 0)
- console->index = 0;
- if (console->setup == NULL ||
- console->setup(console, NULL) == 0) {
- console->flags |= CON_ENABLED;
- if (console->device) {
- console->flags |= CON_CONSDEV;
+ if (newcon->index < 0)
+ newcon->index = 0;
+ if (newcon->setup == NULL ||
+ newcon->setup(newcon, NULL) == 0) {
+ newcon->flags |= CON_ENABLED;
+ if (newcon->device) {
+ newcon->flags |= CON_CONSDEV;
preferred_console = 0;
}
}
@@ -1178,47 +1208,53 @@ void register_console(struct console *console)
*/
for (i = 0; i < MAX_CMDLINECONSOLES && console_cmdline[i].name[0];
i++) {
- if (strcmp(console_cmdline[i].name, console->name) != 0)
+ if (strcmp(console_cmdline[i].name, newcon->name) != 0)
continue;
- if (console->index >= 0 &&
- console->index != console_cmdline[i].index)
+ if (newcon->index >= 0 &&
+ newcon->index != console_cmdline[i].index)
continue;
- if (console->index < 0)
- console->index = console_cmdline[i].index;
+ if (newcon->index < 0)
+ newcon->index = console_cmdline[i].index;
#ifdef CONFIG_A11Y_BRAILLE_CONSOLE
if (console_cmdline[i].brl_options) {
- console->flags |= CON_BRL;
- braille_register_console(console,
+ newcon->flags |= CON_BRL;
+ braille_register_console(newcon,
console_cmdline[i].index,
console_cmdline[i].options,
console_cmdline[i].brl_options);
return;
}
#endif
- if (console->setup &&
- console->setup(console, console_cmdline[i].options) != 0)
+ if (newcon->setup &&
+ newcon->setup(newcon, console_cmdline[i].options) != 0)
break;
- console->flags |= CON_ENABLED;
- console->index = console_cmdline[i].index;
+ newcon->flags |= CON_ENABLED;
+ newcon->index = console_cmdline[i].index;
if (i == selected_console) {
- console->flags |= CON_CONSDEV;
+ newcon->flags |= CON_CONSDEV;
preferred_console = selected_console;
}
break;
}
- if (!(console->flags & CON_ENABLED))
+ if (!(newcon->flags & CON_ENABLED))
return;
- if (bootconsole && (console->flags & CON_CONSDEV)) {
- printk(KERN_INFO "console handover: boot [%s%d] -> real [%s%d]\n",
- bootconsole->name, bootconsole->index,
- console->name, console->index);
- unregister_console(bootconsole);
- console->flags &= ~CON_PRINTBUFFER;
+ if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV)) {
+ /* we need to iterate through twice, to make sure we print
+ * everything out, before we unregister the console(s)
+ */
+ printk(KERN_INFO "console handover:");
+ for_each_console(bcon)
+ printk("boot [%s%d] ", bcon->name, bcon->index);
+ printk(" -> real [%s%d]\n", newcon->name, newcon->index);
+ for_each_console(bcon)
+ unregister_console(bcon);
+ newcon->flags &= ~CON_PRINTBUFFER;
} else {
- printk(KERN_INFO "console [%s%d] enabled\n",
- console->name, console->index);
+ printk(KERN_INFO "%sconsole [%s%d] enabled\n",
+ (newcon->flags & CON_BOOT) ? "boot" : "" ,
+ newcon->name, newcon->index);
}
/*
@@ -1226,16 +1262,16 @@ void register_console(struct console *console)
* preferred driver at the head of the list.
*/
acquire_console_sem();
- if ((console->flags & CON_CONSDEV) || console_drivers == NULL) {
- console->next = console_drivers;
- console_drivers = console;
- if (console->next)
- console->next->flags &= ~CON_CONSDEV;
+ if ((newcon->flags & CON_CONSDEV) || console_drivers == NULL) {
+ newcon->next = console_drivers;
+ console_drivers = newcon;
+ if (newcon->next)
+ newcon->next->flags &= ~CON_CONSDEV;
} else {
- console->next = console_drivers->next;
- console_drivers->next = console;
+ newcon->next = console_drivers->next;
+ console_drivers->next = newcon;
}
- if (console->flags & CON_PRINTBUFFER) {
+ if (newcon->flags & CON_PRINTBUFFER) {
/*
* release_console_sem() will print out the buffered messages
* for us.
@@ -1287,11 +1323,13 @@ EXPORT_SYMBOL(unregister_console);
static int __init disable_boot_consoles(void)
{
- if (console_drivers != NULL) {
- if (console_drivers->flags & CON_BOOT) {
+ struct console *con;
+
+ for_each_console(con) {
+ if (con->flags & CON_BOOT) {
printk(KERN_INFO "turn off boot console %s%d\n",
- console_drivers->name, console_drivers->index);
- return unregister_console(console_drivers);
+ con->name, con->index);
+ return unregister_console(con);
}
}
return 0;
generated by cgit v1.2.3 (git 2.25.1) at 2024-11-18 10:00:53 +0000