linux-kernel - Fwd: [PATCH] kdb: Avoid using dbg_io

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Date:	Tue, 20 Mar 2012 09:34:08 -0700
From:	Tim Bird <tim.bird@...sony.com>
To:	Jason Wessel <jason.wessel@...driver.com>
CC:	"kgdb-bugreport@...ts.sourceforge.net" 
	<kgdb-bugreport@...ts.sourceforge.net>,
	linux kernel <linux-kernel@...r.kernel.org>
Subject: Fwd: [PATCH] kdb:  Avoid using dbg_io_ops until it is initialized

Jason,

This patch has apparently fallen through the cracks.  Can you please apply?
This fixes a kernel panic for a use case where I'm setting a breakpoint
from kdb_cmds on kernel startup.  In this case, without this patch
dbg_io_ops is used before it is initialized.

Thanks,
 -- Tim

-------- Original Message --------
Subject: [PATCH] kdb:  Avoid using dbg_io_ops until it is initialized
Date: Wed, 21 Sep 2011 13:19:12 -0700
From: Tim Bird <tim.bird@...sony.com>
To: Jason Wessel <jason.wessel@...driver.com>
CC: kgdb-bugreport@...ts.sourceforge.net	<kgdb-bugreport@...ts.sourceforge.net>, linux kernel	<linux-kernel@...r.kernel.org>

This fixes a bug with setting a breakpoint during kdb initialization
(from kdb_cmds).  Any call to kdb_printf() before the initialization
of the kgdboc serial console driver (which happens much later in
bootup than kdb_init), results in kernel panic due to the use of
dbg_io_ops before it is initialized.

Signed-off-by: Tim Bird <tim.bird@...sony.com>
---
 kernel/debug/kdb/kdb_io.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/debug/kdb/kdb_io.c b/kernel/debug/kdb/kdb_io.c
index c9b7f4f..3bc995f 100644
--- a/kernel/debug/kdb/kdb_io.c
+++ b/kernel/debug/kdb/kdb_io.c
@@ -675,7 +675,7 @@ kdb_printit:
 	if (!dbg_kdb_mode && kgdb_connected) {
 		gdbstub_msg_write(kdb_buffer, retlen);
 	} else {
-		if (!dbg_io_ops->is_console) {
+		if (dbg_io_ops && !dbg_io_ops->is_console) {
 			len = strlen(kdb_buffer);
 			cp = kdb_buffer;
 			while (len--) {
-- 
1.7.2.3



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