Fixes and cleanups for earlyprintk aka boot console

The console subsystem already has an idea of a boot console, using the
CON_BOOT flag.  The implementation has some flaws though.  The major
problem is that presence of a boot console makes register_console() ignore
any other console devices (unless explicitly specified on the kernel
command line).

This patch fixes the console selection code to *not* consider a boot
console a full-featured one, so the first non-boot console registering will
become the default console instead.  This way the unregister call for the
boot console in the register_console() function actually triggers and the
handover from the boot console to the real console device works smoothly.
Added a printk for the handover, so you know which console device the
output goes to when the boot console stops printing messages.

The disable_early_printk() call is obsolete with that patch, explicitly
disabling the early console isn't needed any more as it works automagically
with that patch.

I've walked through the tree, dropped all disable_early_printk() instances
found below arch/ and tagged the consoles with CON_BOOT if needed.  The
code is tested on x86, sh (thanks to Paul) and mips (thanks to Ralf).

Changes to last version: Rediffed against -rc3, adapted to mips cleanups by
Ralf, fixed "udbg-immortal" cmd line arg on powerpc.

Signed-off-by: Gerd Hoffmann <kraxel@exsuse.de>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Acked-by: Ralf Baechle <ralf@linux-mips.org>
Cc: Andi Kleen <ak@suse.de>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Cc: Richard Henderson <rth@twiddle.net>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Jeremy Fitzhardinge <jeremy@goop.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

7 files changed, 19 insertions, 62 deletions

diff --git a/arch/alpha/kernel/setup.c b/arch/alpha/kernel/setup.c
index d352c2b05f1a..915f26345c45 100644
--- a/arch/alpha/kernel/setup.c
+++ b/arch/alpha/kernel/setup.c
@@ -744,15 +744,6 @@ setup_arch(char **cmdline_p)
 	paging_init();
 }
 
-void __init
-disable_early_printk(void)
-{
-	if (alpha_using_srm && srmcons_output) {
-		unregister_srm_console();
-		srmcons_output = 0;
-	}
-}
-
 static char sys_unknown[] = "Unknown";
 static char systype_names[][16] = {
 	"0",
diff --git a/arch/alpha/kernel/srmcons.c b/arch/alpha/kernel/srmcons.c
index 85a821aaceb4..930cedc8be24 100644
--- a/arch/alpha/kernel/srmcons.c
+++ b/arch/alpha/kernel/srmcons.c
@@ -300,7 +300,7 @@ static struct console srmcons = {
 	.write		= srm_console_write,
 	.device		= srm_console_device,
 	.setup		= srm_console_setup,
-	.flags		= CON_PRINTBUFFER,
+	.flags		= CON_PRINTBUFFER | CON_BOOT,
 	.index		= -1,
 };
 
diff --git a/arch/mips/kernel/early_printk.c b/arch/mips/kernel/early_printk.c
index 304efdc5682f..4fa54b230c09 100644
--- a/arch/mips/kernel/early_printk.c
+++ b/arch/mips/kernel/early_printk.c
@@ -33,8 +33,3 @@ void __init setup_early_printk(void)
 {
 	register_console(&early_console);
 }
-
-void __init disable_early_printk(void)
-{
-	unregister_console(&early_console);
-}
diff --git a/arch/powerpc/kernel/udbg.c b/arch/powerpc/kernel/udbg.c
index 7e0971868fc2..147a2d83de10 100644
--- a/arch/powerpc/kernel/udbg.c
+++ b/arch/powerpc/kernel/udbg.c
@@ -142,29 +142,22 @@ static void udbg_console_write(struct console *con, const char *s,
 static struct console udbg_console = {
 	.name	= "udbg",
 	.write	= udbg_console_write,
-	.flags	= CON_PRINTBUFFER | CON_ENABLED,
+	.flags	= CON_PRINTBUFFER | CON_ENABLED | CON_BOOT,
 	.index	= -1,
 };
 
 static int early_console_initialized;
 
-void __init disable_early_printk(void)
-{
-	if (!early_console_initialized)
-		return;
-	if (strstr(boot_command_line, "udbg-immortal")) {
-		printk(KERN_INFO "early console immortal !\n");
-		return;
-	}
-	unregister_console(&udbg_console);
-	early_console_initialized = 0;
-}
-
 /* called by setup_system */
 void register_early_udbg_console(void)
 {
 	if (early_console_initialized)
 		return;
+
+	if (strstr(boot_command_line, "udbg-immortal")) {
+		printk(KERN_INFO "early console immortal !\n");
+		udbg_console.flags &= ~CON_BOOT;
+	}
 	early_console_initialized = 1;
 	register_console(&udbg_console);
 }
diff --git a/arch/sh/kernel/early_printk.c b/arch/sh/kernel/early_printk.c
index 9048c0326d87..9833493d8867 100644
--- a/arch/sh/kernel/early_printk.c
+++ b/arch/sh/kernel/early_printk.c
@@ -192,20 +192,14 @@ int __init setup_early_printk(char *buf)
 	}
 #endif
 
-	if (likely(early_console))
+	if (likely(early_console)) {
+		if (keep_early)
+			early_console->flags &= ~CON_BOOT;
+		else
+			early_console->flags |= CON_BOOT;
 		register_console(early_console);
+	}
 
 	return 0;
 }
 early_param("earlyprintk", setup_early_printk);
-
-void __init disable_early_printk(void)
-{
-	if (!early_console_initialized || !early_console)
-		return;
-	if (!keep_early) {
-		printk("disabling early console\n");
-		unregister_console(early_console);
-	} else
-		printk("keeping early console\n");
-}
diff --git a/arch/sh64/kernel/early_printk.c b/arch/sh64/kernel/early_printk.c
index 8c8a76e180aa..4f9131123672 100644
--- a/arch/sh64/kernel/early_printk.c
+++ b/arch/sh64/kernel/early_printk.c
@@ -79,7 +79,7 @@ static struct console sh_console = {
 	.name		= "scifcon",
 	.write		= sh_console_write,
 	.setup		= sh_console_setup,
-	.flags		= CON_PRINTBUFFER,
+	.flags		= CON_PRINTBUFFER | CON_BOOT,
 	.index		= -1,
 };
 
@@ -97,9 +97,3 @@ void __init enable_early_printk(void)
 
 	register_console(&sh_console);
 }
-
-void disable_early_printk(void)
-{
-	unregister_console(&sh_console);
-}
-
diff --git a/arch/x86_64/kernel/early_printk.c b/arch/x86_64/kernel/early_printk.c
index 92213d2b7c11..56eaa259782b 100644
--- a/arch/x86_64/kernel/early_printk.c
+++ b/arch/x86_64/kernel/early_printk.c
@@ -243,22 +243,12 @@ static int __init setup_early_printk(char *buf)
  		early_console = &simnow_console;
  		keep_early = 1;
 	}
+
+	if (keep_early)
+		early_console->flags &= ~CON_BOOT;
+	else
+		early_console->flags |= CON_BOOT;
 	register_console(early_console);
 	return 0;
 }
-
 early_param("earlyprintk", setup_early_printk);
-
-void __init disable_early_printk(void)
-{
-	if (!early_console_initialized || !early_console)
-		return;
-	if (!keep_early) {
-		printk("disabling early console\n");
-		unregister_console(early_console);
-		early_console_initialized = 0;
-	} else {
-		printk("keeping early console\n");
-	}
-}
-