rt-patches/0056-genirq-Do-not-invoke-the-affinity-callback-via-a-wor.patch

   1 From f2026ab95a3cee03145a08474c3feec39cbaad22 Mon Sep 17 00:00:00 2001
   2 From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
   3 Date: Wed, 21 Aug 2013 17:48:46 +0200
   4 Subject: [PATCH 056/365] genirq: Do not invoke the affinity callback via a
   5  workqueue on RT
   6
   7 Joe Korty reported, that __irq_set_affinity_locked() schedules a
   8 workqueue while holding a rawlock which results in a might_sleep()
   9 warning.
  10 This patch moves the invokation into a process context so that we only
  11 wakeup() a process while holding the lock.
  12
  13 Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
  14 ---
  15  include/linux/interrupt.h |  1 +
  16  kernel/irq/manage.c       | 79 +++++++++++++++++++++++++++++++++++++++++++++--
  17  2 files changed, 77 insertions(+), 3 deletions(-)
  18
  19 diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
  20 index 48407e6..248380d 100644
  21 --- a/include/linux/interrupt.h
  22 +++ b/include/linux/interrupt.h
  23 @@ -217,6 +217,7 @@ struct irq_affinity_notify {
  24         unsigned int irq;
  25         struct kref kref;
  26         struct work_struct work;
  27 +       struct list_head list;
  28         void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
  29         void (*release)(struct kref *ref);
  30  };
  31 diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
  32 index 8ca0dcd..8842388 100644
  33 --- a/kernel/irq/manage.c
  34 +++ b/kernel/irq/manage.c
  35 @@ -183,6 +183,62 @@ static inline void
  36  irq_get_pending(struct cpumask *mask, struct irq_desc *desc) { }
  37  #endif
  38
  39 +#ifdef CONFIG_PREEMPT_RT_FULL
  40 +static void _irq_affinity_notify(struct irq_affinity_notify *notify);
  41 +static struct task_struct *set_affinity_helper;
  42 +static LIST_HEAD(affinity_list);
  43 +static DEFINE_RAW_SPINLOCK(affinity_list_lock);
  44 +
  45 +static int set_affinity_thread(void *unused)
  46 +{
  47 +       while (1) {
  48 +               struct irq_affinity_notify *notify;
  49 +               int empty;
  50 +
  51 +               set_current_state(TASK_INTERRUPTIBLE);
  52 +
  53 +               raw_spin_lock_irq(&affinity_list_lock);
  54 +               empty = list_empty(&affinity_list);
  55 +               raw_spin_unlock_irq(&affinity_list_lock);
  56 +
  57 +               if (empty)
  58 +                       schedule();
  59 +               if (kthread_should_stop())
  60 +                       break;
  61 +               set_current_state(TASK_RUNNING);
  62 +try_next:
  63 +               notify = NULL;
  64 +
  65 +               raw_spin_lock_irq(&affinity_list_lock);
  66 +               if (!list_empty(&affinity_list)) {
  67 +                       notify = list_first_entry(&affinity_list,
  68 +                                       struct irq_affinity_notify, list);
  69 +                       list_del_init(&notify->list);
  70 +               }
  71 +               raw_spin_unlock_irq(&affinity_list_lock);
  72 +
  73 +               if (!notify)
  74 +                       continue;
  75 +               _irq_affinity_notify(notify);
  76 +               goto try_next;
  77 +       }
  78 +       return 0;
  79 +}
  80 +
  81 +static void init_helper_thread(void)
  82 +{
  83 +       if (set_affinity_helper)
  84 +               return;
  85 +       set_affinity_helper = kthread_run(set_affinity_thread, NULL,
  86 +                       "affinity-cb");
  87 +       WARN_ON(IS_ERR(set_affinity_helper));
  88 +}
  89 +#else
  90 +
  91 +static inline void init_helper_thread(void) { }
  92 +
  93 +#endif
  94 +
  95  int irq_do_set_affinity(struct irq_data *data, const struct cpumask *mask,
  96                         bool force)
  97  {
  98 @@ -222,7 +278,17 @@ int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
  99
 100         if (desc->affinity_notify) {
 101                 kref_get(&desc->affinity_notify->kref);
 102 +
 103 +#ifdef CONFIG_PREEMPT_RT_FULL
 104 +               raw_spin_lock(&affinity_list_lock);
 105 +               if (list_empty(&desc->affinity_notify->list))
 106 +                       list_add_tail(&affinity_list,
 107 +                                       &desc->affinity_notify->list);
 108 +               raw_spin_unlock(&affinity_list_lock);
 109 +               wake_up_process(set_affinity_helper);
 110 +#else
 111                 schedule_work(&desc->affinity_notify->work);
 112 +#endif
 113         }
 114         irqd_set(data, IRQD_AFFINITY_SET);
 115
 116 @@ -260,10 +326,8 @@ int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m)
 117  }
 118  EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 119
 120 -static void irq_affinity_notify(struct work_struct *work)
 121 +static void _irq_affinity_notify(struct irq_affinity_notify *notify)
 122  {
 123 -       struct irq_affinity_notify *notify =
 124 -               container_of(work, struct irq_affinity_notify, work);
 125         struct irq_desc *desc = irq_to_desc(notify->irq);
 126         cpumask_var_t cpumask;
 127         unsigned long flags;
 128 @@ -285,6 +349,13 @@ out:
 129         kref_put(&notify->kref, notify->release);
 130  }
 131
 132 +static void irq_affinity_notify(struct work_struct *work)
 133 +{
 134 +       struct irq_affinity_notify *notify =
 135 +               container_of(work, struct irq_affinity_notify, work);
 136 +       _irq_affinity_notify(notify);
 137 +}
 138 +
 139  /**
 140   *     irq_set_affinity_notifier - control notification of IRQ affinity changes
 141   *     @irq:           Interrupt for which to enable/disable notification
 142 @@ -314,6 +385,8 @@ irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 143                 notify->irq = irq;
 144                 kref_init(&notify->kref);
 145                 INIT_WORK(&notify->work, irq_affinity_notify);
 146 +               INIT_LIST_HEAD(&notify->list);
 147 +               init_helper_thread();
 148         }
 149
 150         raw_spin_lock_irqsave(&desc->lock, flags);
 151 --
 152 2.7.4
 153