linux-kernel - [31/55] powerpc/kdump: Fix timeout in crash_kexec_wait

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Message-Id: <20110806000251.978851298@clark.kroah.org>
Date:	Fri, 05 Aug 2011 17:02:01 -0700
From:	Greg KH <gregkh@...e.de>
To:	linux-kernel@...r.kernel.org, stable@...nel.org
Cc:	stable-review@...nel.org, torvalds@...ux-foundation.org,
	akpm@...ux-foundation.org, alan@...rguk.ukuu.org.uk,
	Anton Blanchard <anton@...ba.org>,
	Michael Neuling <mikey@...ling.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>
Subject: [31/55] powerpc/kdump: Fix timeout in crash_kexec_wait_realmode

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

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

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

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 file changed, 1 insertion(+), 5 deletions(-)

--- a/arch/powerpc/kernel/crash.c
+++ b/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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