linux-kernel - [PATCH 4/7] kdb: Fix early debugging crash regression

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Date:	Fri, 29 Oct 2010 13:43:38 -0500
From:	Jason Wessel <jason.wessel@...driver.com>
To:	torvalds@...ux-foundation.org
Cc:	linux-kernel@...r.kernel.org, kgdb-bugreport@...ts.sourceforge.net,
	Jason Wessel <jason.wessel@...driver.com>
Subject: [PATCH 4/7] kdb: Fix early debugging crash regression

The kdb_current legally be equal to NULL in the early boot of the x86
arch.  The problem pcan be observed by booting with the kernel arguments:

    earlyprintk=vga ekgdboc=kbd kgdbwait

The kdb shell will oops on entry and recursively fault because it
cannot get past the final stage of shell initialization.

Signed-off-by: Jason Wessel <jason.wessel@...driver.com>
---
 kernel/debug/kdb/kdb_main.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)

diff --git a/kernel/debug/kdb/kdb_main.c b/kernel/debug/kdb/kdb_main.c
index 9755ac0..37755d6 100644
--- a/kernel/debug/kdb/kdb_main.c
+++ b/kernel/debug/kdb/kdb_main.c
@@ -1127,7 +1127,7 @@ static int kdb_local(kdb_reason_t reason, int error, struct pt_regs *regs,
 		/* special case below */
 	} else {
 		kdb_printf("\nEntering kdb (current=0x%p, pid %d) ",
-			   kdb_current, kdb_current->pid);
+			   kdb_current, kdb_current ? kdb_current->pid : 0);
 #if defined(CONFIG_SMP)
 		kdb_printf("on processor %d ", raw_smp_processor_id());
 #endif
-- 
1.6.3.3

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