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Subject[tip:x86/uv] x86/uv: Fix the UV BAU destination timeout period
Commit-ID:  11cab711f686893f2696a061dfca30454a624784
Gitweb: http://git.kernel.org/tip/11cab711f686893f2696a061dfca30454a624784
Author: Cliff Wickman <cpw@sgi.com>
AuthorDate: Fri, 22 Jun 2012 08:12:12 -0500
Committer: Ingo Molnar <mingo@kernel.org>
CommitDate: Mon, 25 Jun 2012 14:45:04 +0200

x86/uv: Fix the UV BAU destination timeout period

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>
Link: http://lkml.kernel.org/r/20120622131212.GA31884@sgi.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
---
arch/x86/platform/uv/tlb_uv.c | 4 ++--
1 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/arch/x86/platform/uv/tlb_uv.c b/arch/x86/platform/uv/tlb_uv.c
index 59880af..0c48d43 100644
--- a/arch/x86/platform/uv/tlb_uv.c
+++ b/arch/x86/platform/uv/tlb_uv.c
@@ -1811,8 +1811,8 @@ static int calculate_destination_timeout(void)
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 */

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