linux-kernel - [PATCH] [16/50] powerpc/kdump: Fix timeout in crash_kexec_wait

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Date:	Thu, 28 Jul 2011 16:44:20 -0700 (PDT)
From:	Andi Kleen <andi@...stfloor.org>
To:	mikey@...ling.org, anton@...ba.org, benh@...nel.crashing.org,
	ak@...ux.intel.com, linux-kernel@...r.kernel.org,
	stable@...nel.org, tim.bird@...sony.com
Subject: [PATCH] [16/50] powerpc/kdump: Fix timeout in crash_kexec_wait_realmode

2.6.35-longterm review patch.  If anyone has any objections, please let me know.

------------------
From: Michael Neuling <mikey@...ling.org>

[ upstream commit 63f21a56f1cc0b800a4c00349c59448f82473d19 ]

The existing code it pretty ugly.  How about we clean it up even more
like this?

From: Anton Blanchard <anton@...ba.org>

We check for timeout expiry in the outer loop, but we also need to
check it in the inner loop or we can lock up forever waiting for a
CPU to hit real mode.

Signed-off-by: Anton Blanchard <anton@...ba.org>
Signed-off-by: Michael Neuling <mikey@...ling.org>
Cc: <stable@...nel.org>
Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Signed-off-by: Andi Kleen <ak@...ux.intel.com>

Index: linux-2.6.35.y/arch/powerpc/kernel/crash.c
===================================================================
--- linux-2.6.35.y.orig/arch/powerpc/kernel/crash.c
+++ linux-2.6.35.y/arch/powerpc/kernel/crash.c
@@ -176,12 +176,8 @@ static void crash_kexec_wait_realmode(in
 
 		while (paca[i].kexec_state < KEXEC_STATE_REAL_MODE) {
 			barrier();
-			if (!cpu_possible(i)) {
+			if (!cpu_possible(i) || !cpu_online(i) || (msecs <= 0))
 				break;
-			}
-			if (!cpu_online(i)) {
-				break;
-			}
 			msecs--;
 			mdelay(1);
 		}
--
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