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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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