[PATCH 1/1] early_printk: Protect against using the same device twice

[Jason Wessel]

If you use the kernel argument:

earlyprintk=serial,ttyS0,115200

This will cause a recursive crash.  Instead warn the end user that they
specified the device a second time.

Signed-off-by: Jason Wessel <jason.wessel@xxxxxxxxxxxxx>
---
 arch/x86/kernel/early_printk.c |    8 ++++++++
 1 files changed, 8 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c
index 2acfd3f..712661a 100644
--- a/arch/x86/kernel/early_printk.c
+++ b/arch/x86/kernel/early_printk.c
@@ -178,11 +178,19 @@ asmlinkage void early_printk(const char *fmt, ...)
 
 static inline void early_console_register(struct console *con, int keep_early)
 {
+	struct console *bcon;
+
 	early_console = con;
 	if (keep_early)
 		early_console->flags &= ~CON_BOOT;
 	else
 		early_console->flags |= CON_BOOT;
+	for (bcon = console_drivers; bcon != NULL; con = bcon->next)
+		if (strcmp(bcon->name, con->name) == 0) {
+			printk(KERN_CRIT "ERROR: earlyprintk= %s console"
+			       " already defined\n", con->name);
+			return;
+		}
 	register_console(early_console);
 }
 
-- 
1.6.3.1.9.g95405b


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