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    Subject[PATCH v2 13/20] ia64: switch do_timer() to xtime_update()
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    local_cpu_data->itm_next = new_itm;  does not need to be protected
    by this lock. and xtime_update() takes the lock itself.


    Cc: Tony Luck <tony.luck@intel.com>
    Cc: Fenghua Yu <fenghua.yu@intel.com>
    Signed-off-by: Torben Hohn <torbenh@gmx.de>
    ---
    arch/ia64/kernel/time.c | 19 +++++--------------
    arch/ia64/xen/time.c | 13 +++++--------
    2 files changed, 10 insertions(+), 22 deletions(-)

    diff --git a/arch/ia64/kernel/time.c b/arch/ia64/kernel/time.c
    index 9702fa9..156ad80 100644
    --- a/arch/ia64/kernel/time.c
    +++ b/arch/ia64/kernel/time.c
    @@ -190,19 +190,10 @@ timer_interrupt (int irq, void *dev_id)

    new_itm += local_cpu_data->itm_delta;

    - if (smp_processor_id() == time_keeper_id) {
    - /*
    - * Here we are in the timer irq handler. We have irqs locally
    - * disabled, but we don't know if the timer_bh is running on
    - * another CPU. We need to avoid to SMP race by acquiring the
    - * xtime_lock.
    - */
    - write_seqlock(&xtime_lock);
    - do_timer(1);
    - local_cpu_data->itm_next = new_itm;
    - write_sequnlock(&xtime_lock);
    - } else
    - local_cpu_data->itm_next = new_itm;
    + if (smp_processor_id() == time_keeper_id)
    + xtime_update(1);
    +
    + local_cpu_data->itm_next = new_itm;

    if (time_after(new_itm, ia64_get_itc()))
    break;
    @@ -222,7 +213,7 @@ skip_process_time_accounting:
    * comfort, we increase the safety margin by
    * intentionally dropping the next tick(s). We do NOT
    * update itm.next because that would force us to call
    - * do_timer() which in turn would let our clock run
    + * xtime_update() which in turn would let our clock run
    * too fast (with the potentially devastating effect
    * of losing monotony of time).
    */
    diff --git a/arch/ia64/xen/time.c b/arch/ia64/xen/time.c
    index c1c5445..1f8244a 100644
    --- a/arch/ia64/xen/time.c
    +++ b/arch/ia64/xen/time.c
    @@ -139,14 +139,11 @@ consider_steal_time(unsigned long new_itm)
    run_posix_cpu_timers(p);
    delta_itm += local_cpu_data->itm_delta * (stolen + blocked);

    - if (cpu == time_keeper_id) {
    - write_seqlock(&xtime_lock);
    - do_timer(stolen + blocked);
    - local_cpu_data->itm_next = delta_itm + new_itm;
    - write_sequnlock(&xtime_lock);
    - } else {
    - local_cpu_data->itm_next = delta_itm + new_itm;
    - }
    + if (cpu == time_keeper_id)
    + xtime_update(stolen + blocked);
    +
    + local_cpu_data->itm_next = delta_itm + new_itm;
    +
    per_cpu(xen_stolen_time, cpu) += NS_PER_TICK * stolen;
    per_cpu(xen_blocked_time, cpu) += NS_PER_TICK * blocked;
    }


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