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 <[email protected]>
To: Jason Wessel <[email protected]>
CC: [email protected] <[email protected]>, linux kernel <[email protected]>

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.

---
 kernel/debug/kdb/kdb_io.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

index c9b7f4f..3bc995f 100644
@@ -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

Many thanks Tim.

I'll review/regression test this and add it to the merge queue. I found another patch from you in the same week from last year that I will also review. I am not exactly sure why these never made it to my review list, but what once was lost is now found.

Cheers,
Jason.