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    SubjectRe: [PATCH tip/core/rcu 15/26] alpha: Fix preemption handling in idle loop
    On Thu, Aug 30, 2012 at 02:05:32PM -0700, Paul E. McKenney wrote:
    > From: Frederic Weisbecker <fweisbec@gmail.com>
    >
    > cpu_idle() is called on the boot CPU by the init code with
    > preemption disabled. But the cpu_idle() function in alpha
    > doesn't handle this when it calls schedule() directly.
    >
    > Fix it by converting it into schedule_preempt_disabled().
    >
    > Also disable preemption before calling cpu_idle() from
    > secondary CPU entry code to stay consistent with this
    > state.
    >
    > Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    > Cc: Richard Henderson <rth@twiddle.net>
    > Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
    > Cc: Matt Turner <mattst88@gmail.com>
    > Cc: alpha <linux-alpha@vger.kernel.org>
    > Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    > Cc: Michael Cree <mcree@orcon.net.nz>

    Reviewed-by: Josh Triplett <josh@joshtriplett.org>

    > arch/alpha/kernel/process.c | 3 ++-
    > arch/alpha/kernel/smp.c | 1 +
    > 2 files changed, 3 insertions(+), 1 deletions(-)
    >
    > diff --git a/arch/alpha/kernel/process.c b/arch/alpha/kernel/process.c
    > index 153d3fc..eac5e01 100644
    > --- a/arch/alpha/kernel/process.c
    > +++ b/arch/alpha/kernel/process.c
    > @@ -56,7 +56,8 @@ cpu_idle(void)
    >
    > while (!need_resched())
    > cpu_relax();
    > - schedule();
    > +
    > + schedule_preempt_disabled();
    > }
    > }
    >
    > diff --git a/arch/alpha/kernel/smp.c b/arch/alpha/kernel/smp.c
    > index 35ddc02..a41ad90 100644
    > --- a/arch/alpha/kernel/smp.c
    > +++ b/arch/alpha/kernel/smp.c
    > @@ -166,6 +166,7 @@ smp_callin(void)
    > DBGS(("smp_callin: commencing CPU %d current %p active_mm %p\n",
    > cpuid, current, current->active_mm));
    >
    > + preempt_disable();
    > /* Do nothing. */
    > cpu_idle();
    > }
    > --
    > 1.7.8
    >


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