drivers/gpu/drm/i915/intel_wakeref.c

   1 /*
   2  * SPDX-License-Identifier: MIT
   3  *
   4  * Copyright © 2019 Intel Corporation
   5  */
   6
   7 #include <linux/wait_bit.h>
   8
   9 #include "intel_runtime_pm.h"
  10 #include "intel_wakeref.h"
  11 #include "i915_drv.h"
  12
  13 int __intel_wakeref_get_first(struct intel_wakeref *wf)
  14 {
  15         intel_wakeref_t wakeref;
  16         int ret = 0;
  17
  18         wakeref = intel_runtime_pm_get(&wf->i915->runtime_pm);
  19         /*
  20          * Treat get/put as different subclasses, as we may need to run
  21          * the put callback from under the shrinker and do not want to
  22          * cross-contanimate that callback with any extra work performed
  23          * upon acquiring the wakeref.
  24          */
  25         mutex_lock_nested(&wf->mutex, SINGLE_DEPTH_NESTING);
  26
  27         if (!atomic_read(&wf->count)) {
  28                 INTEL_WAKEREF_BUG_ON(wf->wakeref);
  29                 wf->wakeref = wakeref;
  30                 wakeref = NULL;
  31
  32                 ret = wf->ops->get(wf);
  33                 if (ret) {
  34                         wakeref = xchg(&wf->wakeref, NULL);
  35                         wake_up_var(&wf->wakeref);
  36                         goto unlock;
  37                 }
  38
  39                 smp_mb__before_atomic(); /* release wf->count */
  40         }
  41
  42         atomic_inc(&wf->count);
  43         INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
  44
  45 unlock:
  46         mutex_unlock(&wf->mutex);
  47         if (unlikely(wakeref))
  48                 intel_runtime_pm_put(&wf->i915->runtime_pm, wakeref);
  49
  50         return ret;
  51 }
  52
  53 static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
  54 {
  55         intel_wakeref_t wakeref = NULL;
  56
  57         INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
  58         if (unlikely(!atomic_dec_and_test(&wf->count)))
  59                 goto unlock;
  60
  61         /* ops->put() must reschedule its own release on error/deferral */
  62         if (likely(!wf->ops->put(wf))) {
  63                 INTEL_WAKEREF_BUG_ON(!wf->wakeref);
  64                 wakeref = xchg(&wf->wakeref, NULL);
  65                 wake_up_var(&wf->wakeref);
  66         }
  67
  68 unlock:
  69         mutex_unlock(&wf->mutex);
  70         if (wakeref)
  71                 intel_runtime_pm_put(&wf->i915->runtime_pm, wakeref);
  72 }
  73
  74 void __intel_wakeref_put_last(struct intel_wakeref *wf, unsigned long flags)
  75 {
  76         INTEL_WAKEREF_BUG_ON(delayed_work_pending(&wf->work));
  77
  78         /* Assume we are not in process context and so cannot sleep. */
  79         if (flags & INTEL_WAKEREF_PUT_ASYNC || !mutex_trylock(&wf->mutex)) {
  80                 mod_delayed_work(wf->i915->unordered_wq, &wf->work,
  81                                  FIELD_GET(INTEL_WAKEREF_PUT_DELAY, flags));
  82                 return;
  83         }
  84
  85         ____intel_wakeref_put_last(wf);
  86 }
  87
  88 static void __intel_wakeref_put_work(struct work_struct *wrk)
  89 {
  90         struct intel_wakeref *wf = container_of(wrk, typeof(*wf), work.work);
  91
  92         if (atomic_add_unless(&wf->count, -1, 1))
  93                 return;
  94
  95         mutex_lock(&wf->mutex);
  96         ____intel_wakeref_put_last(wf);
  97 }
  98
  99 void __intel_wakeref_init(struct intel_wakeref *wf,
 100                           struct drm_i915_private *i915,
 101                           const struct intel_wakeref_ops *ops,
 102                           struct intel_wakeref_lockclass *key,
 103                           const char *name)
 104 {
 105         wf->i915 = i915;
 106         wf->ops = ops;
 107
 108         __mutex_init(&wf->mutex, "wakeref.mutex", &key->mutex);
 109         atomic_set(&wf->count, 0);
 110         wf->wakeref = NULL;
 111
 112         INIT_DELAYED_WORK(&wf->work, __intel_wakeref_put_work);
 113         lockdep_init_map(&wf->work.work.lockdep_map,
 114                          "wakeref.work", &key->work, 0);
 115
 116 #if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
 117         ref_tracker_dir_init(&wf->debug, INTEL_REFTRACK_DEAD_COUNT, name);
 118 #endif
 119 }
 120
 121 int intel_wakeref_wait_for_idle(struct intel_wakeref *wf)
 122 {
 123         int err;
 124
 125         might_sleep();
 126
 127         err = wait_var_event_killable(&wf->wakeref,
 128                                       !intel_wakeref_is_active(wf));
 129         if (err)
 130                 return err;
 131
 132         intel_wakeref_unlock_wait(wf);
 133         return 0;
 134 }
 135
 136 static void wakeref_auto_timeout(struct timer_list *t)
 137 {
 138         struct intel_wakeref_auto *wf = from_timer(wf, t, timer);
 139         intel_wakeref_t wakeref;
 140         unsigned long flags;
 141
 142         if (!refcount_dec_and_lock_irqsave(&wf->count, &wf->lock, &flags))
 143                 return;
 144
 145         wakeref = xchg(&wf->wakeref, NULL);
 146         spin_unlock_irqrestore(&wf->lock, flags);
 147
 148         intel_runtime_pm_put(&wf->i915->runtime_pm, wakeref);
 149 }
 150
 151 void intel_wakeref_auto_init(struct intel_wakeref_auto *wf,
 152                              struct drm_i915_private *i915)
 153 {
 154         spin_lock_init(&wf->lock);
 155         timer_setup(&wf->timer, wakeref_auto_timeout, 0);
 156         refcount_set(&wf->count, 0);
 157         wf->wakeref = NULL;
 158         wf->i915 = i915;
 159 }
 160
 161 void intel_wakeref_auto(struct intel_wakeref_auto *wf, unsigned long timeout)
 162 {
 163         unsigned long flags;
 164
 165         if (!timeout) {
 166                 if (del_timer_sync(&wf->timer))
 167                         wakeref_auto_timeout(&wf->timer);
 168                 return;
 169         }
 170
 171         /* Our mission is that we only extend an already active wakeref */
 172         assert_rpm_wakelock_held(&wf->i915->runtime_pm);
 173
 174         if (!refcount_inc_not_zero(&wf->count)) {
 175                 spin_lock_irqsave(&wf->lock, flags);
 176                 if (!refcount_inc_not_zero(&wf->count)) {
 177                         INTEL_WAKEREF_BUG_ON(wf->wakeref);
 178                         wf->wakeref =
 179                                 intel_runtime_pm_get_if_in_use(&wf->i915->runtime_pm);
 180                         refcount_set(&wf->count, 1);
 181                 }
 182                 spin_unlock_irqrestore(&wf->lock, flags);
 183         }
 184
 185         /*
 186          * If we extend a pending timer, we will only get a single timer
 187          * callback and so need to cancel the local inc by running the
 188          * elided callback to keep the wf->count balanced.
 189          */
 190         if (mod_timer(&wf->timer, jiffies + timeout))
 191                 wakeref_auto_timeout(&wf->timer);
 192 }
 193
 194 void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
 195 {
 196         intel_wakeref_auto(wf, 0);
 197         INTEL_WAKEREF_BUG_ON(wf->wakeref);
 198 }
 199
 200 void intel_ref_tracker_show(struct ref_tracker_dir *dir,
 201                             struct drm_printer *p)
 202 {
 203         const size_t buf_size = PAGE_SIZE;
 204         char *buf, *sb, *se;
 205         size_t count;
 206
 207         buf = kmalloc(buf_size, GFP_NOWAIT);
 208         if (!buf)
 209                 return;
 210
 211         count = ref_tracker_dir_snprint(dir, buf, buf_size);
 212         if (!count)
 213                 goto free;
 214         /* printk does not like big buffers, so we split it */
 215         for (sb = buf; *sb; sb = se + 1) {
 216                 se = strchrnul(sb, '\n');
 217                 drm_printf(p, "%.*s", (int)(se - sb + 1), sb);
 218                 if (!*se)
 219                         break;
 220         }
 221         if (count >= buf_size)
 222                 drm_printf(p, "\n...dropped %zd extra bytes of leak report.\n",
 223                            count + 1 - buf_size);
 224 free:
 225         kfree(buf);
 226 }