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
13int __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(rpm: &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(lock: &wf->mutex, SINGLE_DEPTH_NESTING);
26
27 if (!atomic_read(v: &wf->count)) {
28 INTEL_WAKEREF_BUG_ON(wf->wakeref);
29 wf->wakeref = wakeref;
30 wakeref = 0;
31
32 ret = wf->ops->get(wf);
33 if (ret) {
34 wakeref = xchg(&wf->wakeref, 0);
35 wake_up_var(var: &wf->wakeref);
36 goto unlock;
37 }
38
39 smp_mb__before_atomic(); /* release wf->count */
40 }
41
42 atomic_inc(v: &wf->count);
43 INTEL_WAKEREF_BUG_ON(atomic_read(&wf->count) <= 0);
44
45unlock:
46 mutex_unlock(lock: &wf->mutex);
47 if (unlikely(wakeref))
48 intel_runtime_pm_put(rpm: &wf->i915->runtime_pm, wref: wakeref);
49
50 return ret;
51}
52
53static void ____intel_wakeref_put_last(struct intel_wakeref *wf)
54{
55 intel_wakeref_t wakeref = 0;
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, 0);
65 wake_up_var(var: &wf->wakeref);
66 }
67
68unlock:
69 mutex_unlock(lock: &wf->mutex);
70 if (wakeref)
71 intel_runtime_pm_put(rpm: &wf->i915->runtime_pm, wref: wakeref);
72}
73
74void __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(lock: &wf->mutex)) {
80 mod_delayed_work(wq: wf->i915->unordered_wq, dwork: &wf->work,
81 FIELD_GET(INTEL_WAKEREF_PUT_DELAY, flags));
82 return;
83 }
84
85 ____intel_wakeref_put_last(wf);
86}
87
88static 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(v: &wf->count, a: -1, u: 1))
93 return;
94
95 mutex_lock(&wf->mutex);
96 ____intel_wakeref_put_last(wf);
97}
98
99void __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(lock: &wf->mutex, name: "wakeref.mutex", key: &key->mutex);
109 atomic_set(v: &wf->count, i: 0);
110 wf->wakeref = 0;
111
112 INIT_DELAYED_WORK(&wf->work, __intel_wakeref_put_work);
113 lockdep_init_map(lock: &wf->work.work.lockdep_map,
114 name: "wakeref.work", key: &key->work, subclass: 0);
115
116#if IS_ENABLED(CONFIG_DRM_I915_DEBUG_WAKEREF)
117 ref_tracker_dir_init(dir: &wf->debug, INTEL_REFTRACK_DEAD_COUNT, name);
118#endif
119}
120
121int 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
136static 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(r: &wf->count, lock: &wf->lock, flags: &flags))
143 return;
144
145 wakeref = fetch_and_zero(&wf->wakeref);
146 spin_unlock_irqrestore(lock: &wf->lock, flags);
147
148 intel_runtime_pm_put(rpm: &wf->i915->runtime_pm, wref: wakeref);
149}
150
151void 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(r: &wf->count, n: 0);
157 wf->wakeref = 0;
158 wf->i915 = i915;
159}
160
161void 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(timer: &wf->timer))
167 wakeref_auto_timeout(t: &wf->timer);
168 return;
169 }
170
171 /* Our mission is that we only extend an already active wakeref */
172 assert_rpm_wakelock_held(rpm: &wf->i915->runtime_pm);
173
174 if (!refcount_inc_not_zero(r: &wf->count)) {
175 spin_lock_irqsave(&wf->lock, flags);
176 if (!refcount_inc_not_zero(r: &wf->count)) {
177 INTEL_WAKEREF_BUG_ON(wf->wakeref);
178 wf->wakeref =
179 intel_runtime_pm_get_if_in_use(rpm: &wf->i915->runtime_pm);
180 refcount_set(r: &wf->count, n: 1);
181 }
182 spin_unlock_irqrestore(lock: &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(timer: &wf->timer, expires: jiffies + timeout))
191 wakeref_auto_timeout(t: &wf->timer);
192}
193
194void intel_wakeref_auto_fini(struct intel_wakeref_auto *wf)
195{
196 intel_wakeref_auto(wf, timeout: 0);
197 INTEL_WAKEREF_BUG_ON(wf->wakeref);
198}
199
200void 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(size: buf_size, GFP_NOWAIT);
208 if (!buf)
209 return;
210
211 count = ref_tracker_dir_snprint(dir, buf, size: 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, f: "%.*s", (int)(se - sb + 1), sb);
218 if (!*se)
219 break;
220 }
221 if (count >= buf_size)
222 drm_printf(p, f: "\n...dropped %zd extra bytes of leak report.\n",
223 count + 1 - buf_size);
224free:
225 kfree(objp: buf);
226}
227

source code of linux/drivers/gpu/drm/i915/intel_wakeref.c