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Am 2013-03-25 09:59, schrieb Andreas Bießmann:
This patch guards the console_drivers list to be corrupted. The
for_each_console() macro insist on a strictly forward list ended by
NULL:
con0->next->con1->next->NULL
Without this patch it may happen easily to destroy this list for
example by
adding 'earlyprintk' twice, especially on embedded devices where the
early
console is often a single static instance. This will result in the
following
list:
con0->next->con0
This in turn will result in an endless loop in console_unlock() later
on by
printing the first __log_buf line endlessly.
Signed-off-by: Andreas Bießmann <andr...@biessmann.de>
Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Cc: Kay Sievers <k...@vrfy.org>
Cc: Ben Hutchings <b...@decadent.org.uk>
Cc: sta...@kernel.org
---
since v1:
* use WARN() as Ben suggested
* print 'already registered' instead of 'prevent registering'
kernel/printk.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/kernel/printk.c b/kernel/printk.c
index abbdd9e..180ee25 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -2214,6 +2214,13 @@ void register_console(struct console *newcon)
unsigned long flags;
struct console *bcon = NULL;
+ if (console_drivers)
+ for_each_console(bcon)
+ if (WARN(bcon == newcon,
+ "console '%s%d' already registered\n",
+ bcon->name, bcon->index))
+ return;
+
/*
* before we register a new CON_BOOT console, make sure we don't
* already have a valid console
--
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