Commit cd3a1b85 authored May 12, 2008 by Jan Kiszka Committed by Thomas Gleixner May 24, 2008

printk: don't prefer unsuited consoles on registration



console election: If some console happens to be registered first which does
not provide a tty binding (!console->device), it prevents that more suited
consoles which are registered later on can enter the candidate pool for
console_device().  This is observable with KGDB's console which may already
be registered (and exploited!) during early debugger connections, that is
before any regular console registration.

This patch fixes the issue by postponing the final, automated
preferred_console selection until someone with a non-NULL device handler
comes around.

Signed-off-by: Jan Kiszka <jan.kiszka@web.de>
Cc: Jason Wessel <jason.wessel@windriver.com>
Cc: Gerd Hoffmann <kraxel@suse.de>
Cc: Michael Ellerman <michael@ellerman.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

parent 3b8945e8

kernel/printk.c

+5 −2

Original line number	Diff line number	Diff line
		@@ -1157,10 +1157,13 @@ void register_console(struct console *console)
		console->index = 0;
		if (console->setup == NULL \|\|
		console->setup(console, NULL) == 0) {
		console->flags \|= CON_ENABLED \| CON_CONSDEV;
		console->flags \|= CON_ENABLED;
		if (console->device) {
		console->flags \|= CON_CONSDEV;
		preferred_console = 0;
		}
		}
		}

		/*
		* See if this console matches one we selected on

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