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    Subject[PATCH v5 06/18] add_timer_on(): Make sure callers have TIMER_PINNED flag
    Date
    The implementation of the hierachical timer pull model will change the
    timer bases per CPU. Timers, that have to expire on a specific CPU, require
    the TIMER_PINNED flag. Otherwise they will be queued on the dedicated CPU
    but in global timer base and those timers could also expire on other
    CPUs. Timers with TIMER_DEFERRABLE flag end up in a separate base anyway
    and are executed on the local CPU only.

    Therefore add the missing TIMER_PINNED flag for those callers who use
    add_timer_on() without the flag. No functional change.

    Signed-off-by: Anna-Maria Behnsen <anna-maria@linutronix.de>
    Cc: Ingo Molnar <mingo@redhat.com>
    Cc: Borislav Petkov <bp@alien8.de>
    Cc: Dave Hansen <dave.hansen@linux.intel.com>
    Cc: x86@kernel.org
    Cc: "H. Peter Anvin" <hpa@zytor.com>
    Cc: "Theodore Ts'o" <tytso@mit.edu>
    Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>
    Cc: John Stultz <jstultz@google.com>
    Cc: Stephen Boyd <sboyd@kernel.org>
    Cc: Tejun Heo <tj@kernel.org>
    Cc: Lai Jiangshan <jiangshanlai@gmail.com>
    ---
    v5: Add comment in workqueue.c that it's only a workaround for now
    ---
    arch/x86/kernel/tsc_sync.c | 3 ++-
    drivers/char/random.c | 2 +-
    kernel/time/clocksource.c | 2 +-
    kernel/workqueue.c | 15 +++++++++++++--
    4 files changed, 17 insertions(+), 5 deletions(-)

    diff --git a/arch/x86/kernel/tsc_sync.c b/arch/x86/kernel/tsc_sync.c
    index 9452dc9664b5..eab827288e0f 100644
    --- a/arch/x86/kernel/tsc_sync.c
    +++ b/arch/x86/kernel/tsc_sync.c
    @@ -110,7 +110,8 @@ static int __init start_sync_check_timer(void)
    if (!cpu_feature_enabled(X86_FEATURE_TSC_ADJUST) || tsc_clocksource_reliable)
    return 0;

    - timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn, 0);
    + timer_setup(&tsc_sync_check_timer, tsc_sync_check_timer_fn,
    + TIMER_PINNED);
    tsc_sync_check_timer.expires = jiffies + SYNC_CHECK_INTERVAL;
    add_timer(&tsc_sync_check_timer);

    diff --git a/drivers/char/random.c b/drivers/char/random.c
    index ce3ccd172cc8..db6a7c0695de 100644
    --- a/drivers/char/random.c
    +++ b/drivers/char/random.c
    @@ -1007,7 +1007,7 @@ static DEFINE_PER_CPU(struct fast_pool, irq_randomness) = {
    #define FASTMIX_PERM HSIPHASH_PERMUTATION
    .pool = { HSIPHASH_CONST_0, HSIPHASH_CONST_1, HSIPHASH_CONST_2, HSIPHASH_CONST_3 },
    #endif
    - .mix = __TIMER_INITIALIZER(mix_interrupt_randomness, 0)
    + .mix = __TIMER_INITIALIZER(mix_interrupt_randomness, TIMER_PINNED)
    };

    /*
    diff --git a/kernel/time/clocksource.c b/kernel/time/clocksource.c
    index 91836b727cef..e982c119e3c9 100644
    --- a/kernel/time/clocksource.c
    +++ b/kernel/time/clocksource.c
    @@ -561,7 +561,7 @@ static inline void clocksource_start_watchdog(void)
    {
    if (watchdog_running || !watchdog || list_empty(&watchdog_list))
    return;
    - timer_setup(&watchdog_timer, clocksource_watchdog, 0);
    + timer_setup(&watchdog_timer, clocksource_watchdog, TIMER_PINNED);
    watchdog_timer.expires = jiffies + WATCHDOG_INTERVAL;
    add_timer_on(&watchdog_timer, cpumask_first(cpu_online_mask));
    watchdog_running = 1;
    diff --git a/kernel/workqueue.c b/kernel/workqueue.c
    index b8b541caed48..a428d94084ee 100644
    --- a/kernel/workqueue.c
    +++ b/kernel/workqueue.c
    @@ -1677,10 +1677,21 @@ static void __queue_delayed_work(int cpu, struct workqueue_struct *wq,
    dwork->cpu = cpu;
    timer->expires = jiffies + delay;

    - if (unlikely(cpu != WORK_CPU_UNBOUND))
    + if (unlikely(cpu != WORK_CPU_UNBOUND)) {
    + /*
    + * TODO: Setting the flag is a workaround for now; needs to
    + * be cleaned up with new work initializers and defines
    + */
    + timer->flags |= TIMER_PINNED;
    add_timer_on(timer, cpu);
    - else
    + } else {
    + /*
    + * TODO: Resetting the flag is a workaround for now; needs
    + * to be cleaned up with new work initializers and defines
    + */
    + timer->flags &= ~TIMER_PINNED;
    add_timer(timer);
    + }
    }

    /**
    --
    2.30.2
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