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From: Cliff Wickman <cpw@sgi.com>
To: linux-kernel@vger.kernel.org
Cc: mingo@elte.hu, x86@kernel.org
Subject: [PATCH 1/3] x86: UV BAU destination timeout period
Date: Fri, 22 Jun 2012 08:12:12 -0500	[thread overview]
Message-ID: <20120622131212.GA31884@sgi.com> (raw)
In-Reply-To: <E1Si3c5-0008I6-CG@eag09.americas.sgi.com>

Correct the calculation of a destination timeout period, which is used
to distinguish between a destination timeout and the situation where all
the target software ack resources are full and a request is returned
immediately.

The problem is that integer arithmetic was overflowing, yielding a very
large result.

Without this fix destination timeouts are identified as resource 'plugged'
events and an ipi method of resource releasing is unnecessarily employed.

Signed-off-by: Cliff Wickman <cpw@sgi.com>
---
 arch/x86/platform/uv/tlb_uv.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Index: linux/arch/x86/platform/uv/tlb_uv.c
===================================================================
--- linux.orig/arch/x86/platform/uv/tlb_uv.c
+++ linux/arch/x86/platform/uv/tlb_uv.c
@@ -1811,8 +1811,8 @@ static int calculate_destination_timeout
 		index = (mmr_image >> BAU_URGENCY_7_SHIFT) & BAU_URGENCY_7_MASK;
 		mmr_image = uv_read_local_mmr(UVH_TRANSACTION_TIMEOUT);
 		mult2 = (mmr_image >> BAU_TRANS_SHIFT) & BAU_TRANS_MASK;
-		base = timeout_base_ns[index];
-		ts_ns = base * mult1 * mult2;
+		ts_ns = timeout_base_ns[index];
+		ts_ns *= (mult1 * mult2);
 		ret = ts_ns / 1000;
 	} else {
 		/* 4 bits  0/1 for 10/80us base, 3 bits of multiplier */

  reply	other threads:[~2012-06-22 13:12 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2012-06-22 13:09 [PATCH 0/3] x86, UV: BAU additions and fixes Cliff Wickman
2012-06-22 13:12 ` Cliff Wickman [this message]
2012-06-26  5:59   ` [tip:x86/uv] x86/uv: Fix the UV BAU destination timeout period tip-bot for Cliff Wickman
2012-06-22 13:13 ` [PATCH 2/3] x86: UV BAU runtime enable and disable Cliff Wickman
2012-06-26  5:59   ` [tip:x86/uv] x86/uv: Implement UV BAU runtime enable and disable control via /proc/sgi_uv/ tip-bot for Cliff Wickman
2012-06-22 13:14 ` [PATCH 3/3] x86: UV2 BAU hang workarounds Cliff Wickman
2012-06-25 10:03   ` Ingo Molnar
2012-06-25 12:36     ` Cliff Wickman
2012-06-25 12:40       ` Ingo Molnar
2012-06-26  6:00   ` [tip:x86/uv] x86/uv: Work around UV2 BAU hangs tip-bot for Cliff Wickman

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