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    Subject[RFC PATCH 05/12] housekeeping: Use its own static key
    Date
    Housekeeping code still depends on nohz_full static key. Since we want
    to decouple housekeeping from nohz, let's create a housekeeping own static
    key. It's mostly relevant for calls to is_housekeeping_cpu() from the
    scheduler.

    Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
    Cc: Chris Metcalf <cmetcalf@mellanox.com>
    Cc: Rik van Riel <riel@redhat.com>
    Cc: Peter Zijlstra <peterz@infradead.org>
    Cc: Thomas Gleixner <tglx@linutronix.de>
    Cc: Mike Galbraith <efault@gmx.de>
    Cc: Ingo Molnar <mingo@kernel.org>
    Cc: Christoph Lameter <cl@linux.com>
    Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
    Cc: Wanpeng Li <kernellwp@gmail.com>
    Cc: Luiz Capitulino <lcapitulino@redhat.com>
    ---
    include/linux/housekeeping.h | 3 ++-
    kernel/housekeeping.c | 14 +++++++++-----
    2 files changed, 11 insertions(+), 6 deletions(-)

    diff --git a/include/linux/housekeeping.h b/include/linux/housekeeping.h
    index 31a1401..cbe8d63 100644
    --- a/include/linux/housekeeping.h
    +++ b/include/linux/housekeeping.h
    @@ -6,6 +6,7 @@
    #include <linux/tick.h>

    #ifdef CONFIG_NO_HZ_FULL
    +DECLARE_STATIC_KEY_FALSE(housekeeping_overriden);
    extern int housekeeping_any_cpu(void);
    extern const struct cpumask *housekeeping_cpumask(void);
    extern void housekeeping_affine(struct task_struct *t);
    @@ -31,7 +32,7 @@ static inline void housekeeping_init(void) { }
    static inline bool is_housekeeping_cpu(int cpu)
    {
    #ifdef CONFIG_NO_HZ_FULL
    - if (tick_nohz_full_enabled())
    + if (static_branch_unlikely(&housekeeping_overriden))
    return housekeeping_test_cpu(cpu);
    #endif
    return true;
    diff --git a/kernel/housekeeping.c b/kernel/housekeeping.c
    index 0183e75..f8be7e6 100644
    --- a/kernel/housekeeping.c
    +++ b/kernel/housekeeping.c
    @@ -9,12 +9,15 @@
    #include <linux/housekeeping.h>
    #include <linux/tick.h>
    #include <linux/init.h>
    +#include <linux/static_key.h>

    +DEFINE_STATIC_KEY_FALSE(housekeeping_overriden);
    +EXPORT_SYMBOL_GPL(housekeeping_overriden);
    static cpumask_var_t housekeeping_mask;

    int housekeeping_any_cpu(void)
    {
    - if (tick_nohz_full_enabled())
    + if (static_branch_unlikely(&housekeeping_overriden))
    return cpumask_any_and(housekeeping_mask, cpu_online_mask);

    return smp_processor_id();
    @@ -22,7 +25,7 @@ int housekeeping_any_cpu(void)

    const struct cpumask *housekeeping_cpumask(void)
    {
    - if (tick_nohz_full_enabled())
    + if (static_branch_unlikely(&housekeeping_overriden))
    return housekeeping_mask;

    return cpu_possible_mask;
    @@ -30,19 +33,18 @@ const struct cpumask *housekeeping_cpumask(void)

    void housekeeping_affine(struct task_struct *t)
    {
    - if (tick_nohz_full_enabled())
    + if (static_branch_unlikely(&housekeeping_overriden))
    set_cpus_allowed_ptr(t, housekeeping_mask);
    }

    bool housekeeping_test_cpu(int cpu)
    {
    - if (tick_nohz_full_enabled())
    + if (static_branch_unlikely(&housekeeping_overriden))
    return cpumask_test_cpu(cpu, housekeeping_mask);

    return true;
    }

    -
    void __init housekeeping_init(void)
    {
    if (!tick_nohz_full_enabled())
    @@ -58,6 +60,8 @@ void __init housekeeping_init(void)
    cpumask_andnot(housekeeping_mask,
    cpu_possible_mask, tick_nohz_full_mask);

    + static_branch_enable(&housekeeping_overriden);
    +
    /* We need at least one CPU to handle housekeeping work */
    WARN_ON_ONCE(cpumask_empty(housekeeping_mask));
    }
    --
    2.7.4
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