linux-kernel - [PATCH 33/91] powerpc/kdump: Fix timeout in crash_kexec_wait

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Date:	Sun, 05 Feb 2012 23:10:22 +0100
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Anton Blanchard <anton@...ba.org>,
	Michael Neuling <mikey@...ling.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Greg KH <gregkh@...uxfoundation.org>
Subject: [PATCH 33/91] powerpc/kdump: Fix timeout in crash_kexec_wait_realmode

2.6.27-longterm review patch.  If anyone has any objections, please let us know.

------------------

commit 63f21a56f1cc0b800a4c00349c59448f82473d19 upstream.

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>
Signed-off-by: Benjamin Herrenschmidt <benh@...nel.crashing.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...e.de>
---
 arch/powerpc/kernel/crash.c |    6 +-----
 1 files changed, 1 insertions(+), 5 deletions(-)

Index: longterm-2.6.27/arch/powerpc/kernel/crash.c
===================================================================
--- longterm-2.6.27.orig/arch/powerpc/kernel/crash.c	2012-02-05 22:34:33.998915277 +0100
+++ longterm-2.6.27/arch/powerpc/kernel/crash.c	2012-02-05 22:34:39.544914550 +0100
@@ -176,12 +176,8 @@
 
 		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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