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Message-ID: <20090911185522.GA10700@elte.hu>
Date: Fri, 11 Sep 2009 20:55:22 +0200
From: Ingo Molnar <mingo@...e.hu>
To: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: linux-kernel@...r.kernel.org
Subject: [GIT PULL] core/printk for v2.6.32
Linus,
Please pull the latest core-printk-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip.git core-printk-for-linus
Thanks,
Ingo
------------------>
Frans Pop (1):
printk: Restore previous console_loglevel when re-enabling logging
Robin Getz (2):
printk: Enable the use of more than one CON_BOOT (early console)
printk: Ensure that "console enabled" messages are printed on the console
Sonic Zhang (1):
printk: Fix "printk: Enable the use of more than one CON_BOOT (early console)"
kernel/printk.c | 175 +++++++++++++++++++++++++++++++++++++------------------
1 files changed, 118 insertions(+), 57 deletions(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index b4d97b5..e10d193 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, ...)
@@ -61,6 +67,8 @@ int console_printk[4] = {
DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
};
+static int saved_console_loglevel = -1;
+
/*
* Low level drivers may need that to know if they can schedule in
* their unblank() callback or not. So let's export it.
@@ -372,10 +380,15 @@ int do_syslog(int type, char __user *buf, int len)
logged_chars = 0;
break;
case 6: /* Disable logging to console */
+ if (saved_console_loglevel == -1)
+ saved_console_loglevel = console_loglevel;
console_loglevel = minimum_console_loglevel;
break;
case 7: /* Enable logging to console */
- console_loglevel = default_console_loglevel;
+ if (saved_console_loglevel != -1) {
+ console_loglevel = saved_console_loglevel;
+ saved_console_loglevel = -1;
+ }
break;
case 8: /* Set level of messages printed to console */
error = -EINVAL;
@@ -384,6 +397,8 @@ int do_syslog(int type, char __user *buf, int len)
if (len < minimum_console_loglevel)
len = minimum_console_loglevel;
console_loglevel = len;
+ /* Implicitly re-enable logging to console */
+ saved_console_loglevel = -1;
error = 0;
break;
case 9: /* Number of chars in the log buffer */
@@ -412,7 +427,7 @@ 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 +559,7 @@ 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 +1097,7 @@ 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 +1112,7 @@ 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 +1149,49 @@ 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 +1199,13 @@ 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;
}
}
@@ -1178,64 +1217,62 @@ 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;
- } else {
- printk(KERN_INFO "console [%s%d] enabled\n",
- console->name, console->index);
- }
+ /*
+ * If we have a bootconsole, and are switching to a real console,
+ * don't print everything out again, since when the boot console, and
+ * the real console are the same physical device, it's annoying to
+ * see the beginning boot messages twice
+ */
+ if (bcon && ((newcon->flags & (CON_CONSDEV | CON_BOOT)) == CON_CONSDEV))
+ newcon->flags &= ~CON_PRINTBUFFER;
/*
* Put this console in the list - keep the
* 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.
@@ -1245,6 +1282,28 @@ void register_console(struct console *console)
spin_unlock_irqrestore(&logbuf_lock, flags);
}
release_console_sem();
+
+ /*
+ * By unregistering the bootconsoles after we enable the real console
+ * we get the "console xxx enabled" message on all the consoles -
+ * boot consoles, real consoles, etc - this is to ensure that end
+ * users know there might be something in the kernel's log buffer that
+ * went to the bootconsole (that they do not see on the real console)
+ */
+ 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 [%s%d] enabled, bootconsole disabled\n",
+ newcon->name, newcon->index);
+ for_each_console(bcon)
+ if (bcon->flags & CON_BOOT)
+ unregister_console(bcon);
+ } else {
+ printk(KERN_INFO "%sconsole [%s%d] enabled\n",
+ (newcon->flags & CON_BOOT) ? "boot" : "" ,
+ newcon->name, newcon->index);
+ }
}
EXPORT_SYMBOL(register_console);
@@ -1287,11 +1346,13 @@ 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);
+ unregister_console(con);
}
}
return 0;
--
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