From 429a6e5e2c1fbe5d805aad123efbdb5f0c14769f Mon Sep 17 00:00:00 2001 From: Jason Wessel Date: Wed, 23 Sep 2009 18:13:13 -0500 Subject: [PATCH] x86: early_printk: Protect against using the same device twice If you use the kernel argument: earlyprintk=serial,ttyS0,115200 This will cause a recursive hang printing the same line again and again: BIOS-e820: 000000003fff3000 - 0000000040000000 (ACPI data) BIOS-e820: 00000000e0000000 - 00000000f0000000 (reserved) BIOS-e820: 00000000fec00000 - 0000000100000000 (reserved) bootconsole [earlyser0] enabled Linux version 2.6.31-07863-gb64ada6 (mingo@sirius) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #16789 SMP Wed Sep 23 21:09:43 CEST 2009 Linux version 2.6.31-07863-gb64ada6 (mingo@sirius) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #16789 SMP Wed Sep 23 21:09:43 CEST 2009 Linux version 2.6.31-07863-gb64ada6 (mingo@sirius) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #16789 SMP Wed Sep 23 21:09:43 CEST 2009 Linux version 2.6.31-07863-gb64ada6 (mingo@sirius) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #16789 SMP Wed Sep 23 21:09:43 CEST 2009 Linux version 2.6.31-07863-gb64ada6 (mingo@sirius) (gcc version 4.3.2 20081105 (Red Hat 4.3.2-7) (GCC) ) #16789 SMP Wed Sep 23 21:09:43 CEST 2009 Instead warn the end user that they specified the device a second time, and ignore that second console. Reported-by: Ingo Molnar Signed-off-by: Jason Wessel Cc: Len Brown Cc: Greg KH Cc: Andrew Morton Cc: Linus Torvalds LKML-Reference: <4ABAAB89.1080407@windriver.com> Signed-off-by: Ingo Molnar --- arch/x86/kernel/early_printk.c | 5 +++++ 1 file changed, 5 insertions(+) diff --git a/arch/x86/kernel/early_printk.c b/arch/x86/kernel/early_printk.c index 2acfd3fdc0cc..41fd965c80c6 100644 --- a/arch/x86/kernel/early_printk.c +++ b/arch/x86/kernel/early_printk.c @@ -178,6 +178,11 @@ asmlinkage void early_printk(const char *fmt, ...) static inline void early_console_register(struct console *con, int keep_early) { + if (early_console->index != -1) { + printk(KERN_CRIT "ERROR: earlyprintk= %s already used\n", + con->name); + return; + } early_console = con; if (keep_early) early_console->flags &= ~CON_BOOT; -- 2.20.1