151fd371bSRob Clark /*
251fd371bSRob Clark * Copyright (C) 2014 Red Hat
351fd371bSRob Clark * Author: Rob Clark <robdclark@gmail.com>
451fd371bSRob Clark *
551fd371bSRob Clark * Permission is hereby granted, free of charge, to any person obtaining a
651fd371bSRob Clark * copy of this software and associated documentation files (the "Software"),
751fd371bSRob Clark * to deal in the Software without restriction, including without limitation
851fd371bSRob Clark * the rights to use, copy, modify, merge, publish, distribute, sublicense,
951fd371bSRob Clark * and/or sell copies of the Software, and to permit persons to whom the
1051fd371bSRob Clark * Software is furnished to do so, subject to the following conditions:
1151fd371bSRob Clark *
1251fd371bSRob Clark * The above copyright notice and this permission notice shall be included in
1351fd371bSRob Clark * all copies or substantial portions of the Software.
1451fd371bSRob Clark *
1551fd371bSRob Clark * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
1651fd371bSRob Clark * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
1751fd371bSRob Clark * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
1851fd371bSRob Clark * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
1951fd371bSRob Clark * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
2051fd371bSRob Clark * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
2151fd371bSRob Clark * OTHER DEALINGS IN THE SOFTWARE.
2251fd371bSRob Clark */
2351fd371bSRob Clark
24b962a120SRob Clark #include <drm/drm_atomic.h>
2551fd371bSRob Clark #include <drm/drm_crtc.h>
260500c04eSSam Ravnborg #include <drm/drm_device.h>
2751fd371bSRob Clark #include <drm/drm_modeset_lock.h>
28cd06ab2fSJani Nikula #include <drm/drm_print.h>
2951fd371bSRob Clark
3051fd371bSRob Clark /**
3151fd371bSRob Clark * DOC: kms locking
3251fd371bSRob Clark *
3351fd371bSRob Clark * As KMS moves toward more fine grained locking, and atomic ioctl where
3451fd371bSRob Clark * userspace can indirectly control locking order, it becomes necessary
350645de5aSDaniel Vetter * to use &ww_mutex and acquire-contexts to avoid deadlocks. But because
3651fd371bSRob Clark * the locking is more distributed around the driver code, we want a bit
3751fd371bSRob Clark * of extra utility/tracking out of our acquire-ctx. This is provided
38d574528aSDaniel Vetter * by &struct drm_modeset_lock and &struct drm_modeset_acquire_ctx.
3951fd371bSRob Clark *
40387b1468SMauro Carvalho Chehab * For basic principles of &ww_mutex, see: Documentation/locking/ww-mutex-design.rst
4151fd371bSRob Clark *
42da5335b8SDaniel Vetter * The basic usage pattern is to::
4351fd371bSRob Clark *
446f8bcc74SMaarten Lankhorst * drm_modeset_acquire_init(ctx, DRM_MODESET_ACQUIRE_INTERRUPTIBLE)
4551fd371bSRob Clark * retry:
4651fd371bSRob Clark * foreach (lock in random_ordered_set_of_locks) {
476f8bcc74SMaarten Lankhorst * ret = drm_modeset_lock(lock, ctx)
4851fd371bSRob Clark * if (ret == -EDEADLK) {
496f8bcc74SMaarten Lankhorst * ret = drm_modeset_backoff(ctx);
506f8bcc74SMaarten Lankhorst * if (!ret)
5151fd371bSRob Clark * goto retry;
5251fd371bSRob Clark * }
536f8bcc74SMaarten Lankhorst * if (ret)
546f8bcc74SMaarten Lankhorst * goto out;
5551fd371bSRob Clark * }
5651fd371bSRob Clark * ... do stuff ...
576f8bcc74SMaarten Lankhorst * out:
586f8bcc74SMaarten Lankhorst * drm_modeset_drop_locks(ctx);
596f8bcc74SMaarten Lankhorst * drm_modeset_acquire_fini(ctx);
600645de5aSDaniel Vetter *
61b7ea04d2SSean Paul * For convenience this control flow is implemented in
62b7ea04d2SSean Paul * DRM_MODESET_LOCK_ALL_BEGIN() and DRM_MODESET_LOCK_ALL_END() for the case
63b7ea04d2SSean Paul * where all modeset locks need to be taken through drm_modeset_lock_all_ctx().
64b7ea04d2SSean Paul *
65fc2157b6SLiviu Dudau * If all that is needed is a single modeset lock, then the &struct
66fc2157b6SLiviu Dudau * drm_modeset_acquire_ctx is not needed and the locking can be simplified
676f8bcc74SMaarten Lankhorst * by passing a NULL instead of ctx in the drm_modeset_lock() call or
686f8bcc74SMaarten Lankhorst * calling drm_modeset_lock_single_interruptible(). To unlock afterwards
696f8bcc74SMaarten Lankhorst * call drm_modeset_unlock().
70fc2157b6SLiviu Dudau *
71fc2157b6SLiviu Dudau * On top of these per-object locks using &ww_mutex there's also an overall
72d574528aSDaniel Vetter * &drm_mode_config.mutex, for protecting everything else. Mostly this means
730645de5aSDaniel Vetter * probe state of connectors, and preventing hotplug add/removal of connectors.
740645de5aSDaniel Vetter *
750645de5aSDaniel Vetter * Finally there's a bunch of dedicated locks to protect drm core internal
760645de5aSDaniel Vetter * lists and lookup data structures.
7751fd371bSRob Clark */
7851fd371bSRob Clark
7935cf0350SRob Clark static DEFINE_WW_CLASS(crtc_ww_class);
8035cf0350SRob Clark
81cd06ab2fSJani Nikula #if IS_ENABLED(CONFIG_DRM_DEBUG_MODESET_LOCK)
__drm_stack_depot_save(void)82bcae3af2SStephen Rothwell static noinline depot_stack_handle_t __drm_stack_depot_save(void)
83cd06ab2fSJani Nikula {
84cd06ab2fSJani Nikula unsigned long entries[8];
85cd06ab2fSJani Nikula unsigned int n;
86cd06ab2fSJani Nikula
87cd06ab2fSJani Nikula n = stack_trace_save(entries, ARRAY_SIZE(entries), 1);
88cd06ab2fSJani Nikula
89cd06ab2fSJani Nikula return stack_depot_save(entries, n, GFP_NOWAIT | __GFP_NOWARN);
90cd06ab2fSJani Nikula }
91cd06ab2fSJani Nikula
__drm_stack_depot_print(depot_stack_handle_t stack_depot)92bcae3af2SStephen Rothwell static void __drm_stack_depot_print(depot_stack_handle_t stack_depot)
93cd06ab2fSJani Nikula {
94cd06ab2fSJani Nikula struct drm_printer p = drm_debug_printer("drm_modeset_lock");
95cd06ab2fSJani Nikula unsigned long *entries;
96cd06ab2fSJani Nikula unsigned int nr_entries;
97cd06ab2fSJani Nikula char *buf;
98cd06ab2fSJani Nikula
99cd06ab2fSJani Nikula buf = kmalloc(PAGE_SIZE, GFP_NOWAIT | __GFP_NOWARN);
100cd06ab2fSJani Nikula if (!buf)
101cd06ab2fSJani Nikula return;
102cd06ab2fSJani Nikula
103cd06ab2fSJani Nikula nr_entries = stack_depot_fetch(stack_depot, &entries);
104cd06ab2fSJani Nikula stack_trace_snprint(buf, PAGE_SIZE, entries, nr_entries, 2);
105cd06ab2fSJani Nikula
106cd06ab2fSJani Nikula drm_printf(&p, "attempting to lock a contended lock without backoff:\n%s", buf);
107cd06ab2fSJani Nikula
108cd06ab2fSJani Nikula kfree(buf);
109cd06ab2fSJani Nikula }
110*2dba5eb1SVlastimil Babka
__drm_stack_depot_init(void)111*2dba5eb1SVlastimil Babka static void __drm_stack_depot_init(void)
112*2dba5eb1SVlastimil Babka {
113*2dba5eb1SVlastimil Babka stack_depot_init();
114*2dba5eb1SVlastimil Babka }
115cd06ab2fSJani Nikula #else /* CONFIG_DRM_DEBUG_MODESET_LOCK */
__drm_stack_depot_save(void)116bcae3af2SStephen Rothwell static depot_stack_handle_t __drm_stack_depot_save(void)
117cd06ab2fSJani Nikula {
118cd06ab2fSJani Nikula return 0;
119cd06ab2fSJani Nikula }
__drm_stack_depot_print(depot_stack_handle_t stack_depot)120bcae3af2SStephen Rothwell static void __drm_stack_depot_print(depot_stack_handle_t stack_depot)
121cd06ab2fSJani Nikula {
122cd06ab2fSJani Nikula }
__drm_stack_depot_init(void)123*2dba5eb1SVlastimil Babka static void __drm_stack_depot_init(void)
124*2dba5eb1SVlastimil Babka {
125*2dba5eb1SVlastimil Babka }
126cd06ab2fSJani Nikula #endif /* CONFIG_DRM_DEBUG_MODESET_LOCK */
127cd06ab2fSJani Nikula
12851fd371bSRob Clark /**
129bf9e37baSDaniel Vetter * drm_modeset_lock_all - take all modeset locks
13006eaae46SThierry Reding * @dev: DRM device
131a6a8bb84SDaniel Vetter *
132bf9e37baSDaniel Vetter * This function takes all modeset locks, suitable where a more fine-grained
13306eaae46SThierry Reding * scheme isn't (yet) implemented. Locks must be dropped by calling the
13406eaae46SThierry Reding * drm_modeset_unlock_all() function.
13506eaae46SThierry Reding *
13606eaae46SThierry Reding * This function is deprecated. It allocates a lock acquisition context and
137d574528aSDaniel Vetter * stores it in &drm_device.mode_config. This facilitate conversion of
13806eaae46SThierry Reding * existing code because it removes the need to manually deal with the
13906eaae46SThierry Reding * acquisition context, but it is also brittle because the context is global
14006eaae46SThierry Reding * and care must be taken not to nest calls. New code should use the
14106eaae46SThierry Reding * drm_modeset_lock_all_ctx() function and pass in the context explicitly.
142a6a8bb84SDaniel Vetter */
drm_modeset_lock_all(struct drm_device * dev)143bf9e37baSDaniel Vetter void drm_modeset_lock_all(struct drm_device *dev)
144a6a8bb84SDaniel Vetter {
145a6a8bb84SDaniel Vetter struct drm_mode_config *config = &dev->mode_config;
146a6a8bb84SDaniel Vetter struct drm_modeset_acquire_ctx *ctx;
147a6a8bb84SDaniel Vetter int ret;
148a6a8bb84SDaniel Vetter
149d18d1a5aSChris Wilson ctx = kzalloc(sizeof(*ctx), GFP_KERNEL | __GFP_NOFAIL);
150bf9e37baSDaniel Vetter if (WARN_ON(!ctx))
151bf9e37baSDaniel Vetter return;
152a6a8bb84SDaniel Vetter
153a6a8bb84SDaniel Vetter mutex_lock(&config->mutex);
154a6a8bb84SDaniel Vetter
155a6a8bb84SDaniel Vetter drm_modeset_acquire_init(ctx, 0);
156a6a8bb84SDaniel Vetter
157a6a8bb84SDaniel Vetter retry:
15806eaae46SThierry Reding ret = drm_modeset_lock_all_ctx(dev, ctx);
15906eaae46SThierry Reding if (ret < 0) {
160a6a8bb84SDaniel Vetter if (ret == -EDEADLK) {
161a6a8bb84SDaniel Vetter drm_modeset_backoff(ctx);
162a6a8bb84SDaniel Vetter goto retry;
163a6a8bb84SDaniel Vetter }
164cb597bb3SDaniel Vetter
16506eaae46SThierry Reding drm_modeset_acquire_fini(ctx);
166ed181703SOleg Drokin kfree(ctx);
16706eaae46SThierry Reding return;
16806eaae46SThierry Reding }
1695fcdc9d9SMaarten Lankhorst ww_acquire_done(&ctx->ww_ctx);
17006eaae46SThierry Reding
17106eaae46SThierry Reding WARN_ON(config->acquire_ctx);
17206eaae46SThierry Reding
17306eaae46SThierry Reding /*
17406eaae46SThierry Reding * We hold the locks now, so it is safe to stash the acquisition
17506eaae46SThierry Reding * context for drm_modeset_unlock_all().
17606eaae46SThierry Reding */
17706eaae46SThierry Reding config->acquire_ctx = ctx;
17806eaae46SThierry Reding
17906eaae46SThierry Reding drm_warn_on_modeset_not_all_locked(dev);
180a6a8bb84SDaniel Vetter }
181a6a8bb84SDaniel Vetter EXPORT_SYMBOL(drm_modeset_lock_all);
182a6a8bb84SDaniel Vetter
183a6a8bb84SDaniel Vetter /**
184a6a8bb84SDaniel Vetter * drm_modeset_unlock_all - drop all modeset locks
18506eaae46SThierry Reding * @dev: DRM device
186a6a8bb84SDaniel Vetter *
18706eaae46SThierry Reding * This function drops all modeset locks taken by a previous call to the
18806eaae46SThierry Reding * drm_modeset_lock_all() function.
18906eaae46SThierry Reding *
19006eaae46SThierry Reding * This function is deprecated. It uses the lock acquisition context stored
191d574528aSDaniel Vetter * in &drm_device.mode_config. This facilitates conversion of existing
19206eaae46SThierry Reding * code because it removes the need to manually deal with the acquisition
19306eaae46SThierry Reding * context, but it is also brittle because the context is global and care must
19406eaae46SThierry Reding * be taken not to nest calls. New code should pass the acquisition context
19506eaae46SThierry Reding * directly to the drm_modeset_drop_locks() function.
196a6a8bb84SDaniel Vetter */
drm_modeset_unlock_all(struct drm_device * dev)197a6a8bb84SDaniel Vetter void drm_modeset_unlock_all(struct drm_device *dev)
198a6a8bb84SDaniel Vetter {
199a6a8bb84SDaniel Vetter struct drm_mode_config *config = &dev->mode_config;
200a6a8bb84SDaniel Vetter struct drm_modeset_acquire_ctx *ctx = config->acquire_ctx;
201a6a8bb84SDaniel Vetter
202a6a8bb84SDaniel Vetter if (WARN_ON(!ctx))
203a6a8bb84SDaniel Vetter return;
204a6a8bb84SDaniel Vetter
205a6a8bb84SDaniel Vetter config->acquire_ctx = NULL;
206a6a8bb84SDaniel Vetter drm_modeset_drop_locks(ctx);
207a6a8bb84SDaniel Vetter drm_modeset_acquire_fini(ctx);
208a6a8bb84SDaniel Vetter
209a6a8bb84SDaniel Vetter kfree(ctx);
210a6a8bb84SDaniel Vetter
211a6a8bb84SDaniel Vetter mutex_unlock(&dev->mode_config.mutex);
212a6a8bb84SDaniel Vetter }
213a6a8bb84SDaniel Vetter EXPORT_SYMBOL(drm_modeset_unlock_all);
214a6a8bb84SDaniel Vetter
215d059f652SDaniel Vetter /**
216a6a8bb84SDaniel Vetter * drm_warn_on_modeset_not_all_locked - check that all modeset locks are locked
217a6a8bb84SDaniel Vetter * @dev: device
218a6a8bb84SDaniel Vetter *
219a6a8bb84SDaniel Vetter * Useful as a debug assert.
220a6a8bb84SDaniel Vetter */
drm_warn_on_modeset_not_all_locked(struct drm_device * dev)221a6a8bb84SDaniel Vetter void drm_warn_on_modeset_not_all_locked(struct drm_device *dev)
222a6a8bb84SDaniel Vetter {
223a6a8bb84SDaniel Vetter struct drm_crtc *crtc;
224a6a8bb84SDaniel Vetter
225a6a8bb84SDaniel Vetter /* Locking is currently fubar in the panic handler. */
226a6a8bb84SDaniel Vetter if (oops_in_progress)
227a6a8bb84SDaniel Vetter return;
228a6a8bb84SDaniel Vetter
229e4f62546SDaniel Vetter drm_for_each_crtc(crtc, dev)
230a6a8bb84SDaniel Vetter WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
231a6a8bb84SDaniel Vetter
232a6a8bb84SDaniel Vetter WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
233a6a8bb84SDaniel Vetter WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
234a6a8bb84SDaniel Vetter }
235a6a8bb84SDaniel Vetter EXPORT_SYMBOL(drm_warn_on_modeset_not_all_locked);
236a6a8bb84SDaniel Vetter
237a6a8bb84SDaniel Vetter /**
23851fd371bSRob Clark * drm_modeset_acquire_init - initialize acquire context
23951fd371bSRob Clark * @ctx: the acquire context
2406f8bcc74SMaarten Lankhorst * @flags: 0 or %DRM_MODESET_ACQUIRE_INTERRUPTIBLE
2416f8bcc74SMaarten Lankhorst *
2426f8bcc74SMaarten Lankhorst * When passing %DRM_MODESET_ACQUIRE_INTERRUPTIBLE to @flags,
2436f8bcc74SMaarten Lankhorst * all calls to drm_modeset_lock() will perform an interruptible
2446f8bcc74SMaarten Lankhorst * wait.
24551fd371bSRob Clark */
drm_modeset_acquire_init(struct drm_modeset_acquire_ctx * ctx,uint32_t flags)24651fd371bSRob Clark void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
24751fd371bSRob Clark uint32_t flags)
24851fd371bSRob Clark {
249fb54918aSRob Clark memset(ctx, 0, sizeof(*ctx));
25051fd371bSRob Clark ww_acquire_init(&ctx->ww_ctx, &crtc_ww_class);
25151fd371bSRob Clark INIT_LIST_HEAD(&ctx->locked);
2526f8bcc74SMaarten Lankhorst
2536f8bcc74SMaarten Lankhorst if (flags & DRM_MODESET_ACQUIRE_INTERRUPTIBLE)
2546f8bcc74SMaarten Lankhorst ctx->interruptible = true;
25551fd371bSRob Clark }
25651fd371bSRob Clark EXPORT_SYMBOL(drm_modeset_acquire_init);
25751fd371bSRob Clark
25851fd371bSRob Clark /**
25951fd371bSRob Clark * drm_modeset_acquire_fini - cleanup acquire context
26051fd371bSRob Clark * @ctx: the acquire context
26151fd371bSRob Clark */
drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx * ctx)26251fd371bSRob Clark void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx)
26351fd371bSRob Clark {
26451fd371bSRob Clark ww_acquire_fini(&ctx->ww_ctx);
26551fd371bSRob Clark }
26651fd371bSRob Clark EXPORT_SYMBOL(drm_modeset_acquire_fini);
26751fd371bSRob Clark
26851fd371bSRob Clark /**
26951fd371bSRob Clark * drm_modeset_drop_locks - drop all locks
27051fd371bSRob Clark * @ctx: the acquire context
27151fd371bSRob Clark *
27251fd371bSRob Clark * Drop all locks currently held against this acquire context.
27351fd371bSRob Clark */
drm_modeset_drop_locks(struct drm_modeset_acquire_ctx * ctx)27451fd371bSRob Clark void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx)
27551fd371bSRob Clark {
276cd06ab2fSJani Nikula if (WARN_ON(ctx->contended))
277bcae3af2SStephen Rothwell __drm_stack_depot_print(ctx->stack_depot);
278cd06ab2fSJani Nikula
27951fd371bSRob Clark while (!list_empty(&ctx->locked)) {
28051fd371bSRob Clark struct drm_modeset_lock *lock;
28151fd371bSRob Clark
28251fd371bSRob Clark lock = list_first_entry(&ctx->locked,
28351fd371bSRob Clark struct drm_modeset_lock, head);
28451fd371bSRob Clark
28551fd371bSRob Clark drm_modeset_unlock(lock);
28651fd371bSRob Clark }
28751fd371bSRob Clark }
28851fd371bSRob Clark EXPORT_SYMBOL(drm_modeset_drop_locks);
28951fd371bSRob Clark
modeset_lock(struct drm_modeset_lock * lock,struct drm_modeset_acquire_ctx * ctx,bool interruptible,bool slow)29051fd371bSRob Clark static inline int modeset_lock(struct drm_modeset_lock *lock,
29151fd371bSRob Clark struct drm_modeset_acquire_ctx *ctx,
29251fd371bSRob Clark bool interruptible, bool slow)
29351fd371bSRob Clark {
29451fd371bSRob Clark int ret;
29551fd371bSRob Clark
296cd06ab2fSJani Nikula if (WARN_ON(ctx->contended))
297bcae3af2SStephen Rothwell __drm_stack_depot_print(ctx->stack_depot);
29851fd371bSRob Clark
299cb597bb3SDaniel Vetter if (ctx->trylock_only) {
300825926d8SMaarten Lankhorst lockdep_assert_held(&ctx->ww_ctx);
301825926d8SMaarten Lankhorst
30212235da8SMaarten Lankhorst if (!ww_mutex_trylock(&lock->mutex, NULL))
303cb597bb3SDaniel Vetter return -EBUSY;
304cb597bb3SDaniel Vetter else
305cb597bb3SDaniel Vetter return 0;
306cb597bb3SDaniel Vetter } else if (interruptible && slow) {
30751fd371bSRob Clark ret = ww_mutex_lock_slow_interruptible(&lock->mutex, &ctx->ww_ctx);
30851fd371bSRob Clark } else if (interruptible) {
30951fd371bSRob Clark ret = ww_mutex_lock_interruptible(&lock->mutex, &ctx->ww_ctx);
31051fd371bSRob Clark } else if (slow) {
31151fd371bSRob Clark ww_mutex_lock_slow(&lock->mutex, &ctx->ww_ctx);
31251fd371bSRob Clark ret = 0;
31351fd371bSRob Clark } else {
31451fd371bSRob Clark ret = ww_mutex_lock(&lock->mutex, &ctx->ww_ctx);
31551fd371bSRob Clark }
31651fd371bSRob Clark if (!ret) {
31751fd371bSRob Clark WARN_ON(!list_empty(&lock->head));
31851fd371bSRob Clark list_add(&lock->head, &ctx->locked);
31951fd371bSRob Clark } else if (ret == -EALREADY) {
32051fd371bSRob Clark /* we already hold the lock.. this is fine. For atomic
32151fd371bSRob Clark * we will need to be able to drm_modeset_lock() things
32251fd371bSRob Clark * without having to keep track of what is already locked
32351fd371bSRob Clark * or not.
32451fd371bSRob Clark */
32551fd371bSRob Clark ret = 0;
32651fd371bSRob Clark } else if (ret == -EDEADLK) {
32751fd371bSRob Clark ctx->contended = lock;
328bcae3af2SStephen Rothwell ctx->stack_depot = __drm_stack_depot_save();
32951fd371bSRob Clark }
33051fd371bSRob Clark
33151fd371bSRob Clark return ret;
33251fd371bSRob Clark }
33351fd371bSRob Clark
3346f8bcc74SMaarten Lankhorst /**
3356f8bcc74SMaarten Lankhorst * drm_modeset_backoff - deadlock avoidance backoff
3366f8bcc74SMaarten Lankhorst * @ctx: the acquire context
3376f8bcc74SMaarten Lankhorst *
3386f8bcc74SMaarten Lankhorst * If deadlock is detected (ie. drm_modeset_lock() returns -EDEADLK),
3396f8bcc74SMaarten Lankhorst * you must call this function to drop all currently held locks and
3406f8bcc74SMaarten Lankhorst * block until the contended lock becomes available.
3416f8bcc74SMaarten Lankhorst *
3426f8bcc74SMaarten Lankhorst * This function returns 0 on success, or -ERESTARTSYS if this context
3436f8bcc74SMaarten Lankhorst * is initialized with %DRM_MODESET_ACQUIRE_INTERRUPTIBLE and the
3446f8bcc74SMaarten Lankhorst * wait has been interrupted.
3456f8bcc74SMaarten Lankhorst */
drm_modeset_backoff(struct drm_modeset_acquire_ctx * ctx)3466f8bcc74SMaarten Lankhorst int drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx)
34751fd371bSRob Clark {
34851fd371bSRob Clark struct drm_modeset_lock *contended = ctx->contended;
34951fd371bSRob Clark
35051fd371bSRob Clark ctx->contended = NULL;
351cd06ab2fSJani Nikula ctx->stack_depot = 0;
35251fd371bSRob Clark
35351fd371bSRob Clark if (WARN_ON(!contended))
35451fd371bSRob Clark return 0;
35551fd371bSRob Clark
35651fd371bSRob Clark drm_modeset_drop_locks(ctx);
35751fd371bSRob Clark
3586f8bcc74SMaarten Lankhorst return modeset_lock(contended, ctx, ctx->interruptible, true);
35951fd371bSRob Clark }
36051fd371bSRob Clark EXPORT_SYMBOL(drm_modeset_backoff);
36151fd371bSRob Clark
36251fd371bSRob Clark /**
36335cf0350SRob Clark * drm_modeset_lock_init - initialize lock
36435cf0350SRob Clark * @lock: lock to init
36535cf0350SRob Clark */
drm_modeset_lock_init(struct drm_modeset_lock * lock)36635cf0350SRob Clark void drm_modeset_lock_init(struct drm_modeset_lock *lock)
36735cf0350SRob Clark {
36835cf0350SRob Clark ww_mutex_init(&lock->mutex, &crtc_ww_class);
36935cf0350SRob Clark INIT_LIST_HEAD(&lock->head);
370*2dba5eb1SVlastimil Babka __drm_stack_depot_init();
37135cf0350SRob Clark }
37235cf0350SRob Clark EXPORT_SYMBOL(drm_modeset_lock_init);
37335cf0350SRob Clark
37435cf0350SRob Clark /**
37551fd371bSRob Clark * drm_modeset_lock - take modeset lock
37651fd371bSRob Clark * @lock: lock to take
37751fd371bSRob Clark * @ctx: acquire ctx
37851fd371bSRob Clark *
379fc2157b6SLiviu Dudau * If @ctx is not NULL, then its ww acquire context is used and the
38051fd371bSRob Clark * lock will be tracked by the context and can be released by calling
38151fd371bSRob Clark * drm_modeset_drop_locks(). If -EDEADLK is returned, this means a
38251fd371bSRob Clark * deadlock scenario has been detected and it is an error to attempt
38351fd371bSRob Clark * to take any more locks without first calling drm_modeset_backoff().
384fc2157b6SLiviu Dudau *
3856f8bcc74SMaarten Lankhorst * If the @ctx is not NULL and initialized with
3866f8bcc74SMaarten Lankhorst * %DRM_MODESET_ACQUIRE_INTERRUPTIBLE, this function will fail with
3876f8bcc74SMaarten Lankhorst * -ERESTARTSYS when interrupted.
3886f8bcc74SMaarten Lankhorst *
389fc2157b6SLiviu Dudau * If @ctx is NULL then the function call behaves like a normal,
3906f8bcc74SMaarten Lankhorst * uninterruptible non-nesting mutex_lock() call.
39151fd371bSRob Clark */
drm_modeset_lock(struct drm_modeset_lock * lock,struct drm_modeset_acquire_ctx * ctx)39251fd371bSRob Clark int drm_modeset_lock(struct drm_modeset_lock *lock,
39351fd371bSRob Clark struct drm_modeset_acquire_ctx *ctx)
39451fd371bSRob Clark {
39551fd371bSRob Clark if (ctx)
3966f8bcc74SMaarten Lankhorst return modeset_lock(lock, ctx, ctx->interruptible, false);
39751fd371bSRob Clark
39851fd371bSRob Clark ww_mutex_lock(&lock->mutex, NULL);
39951fd371bSRob Clark return 0;
40051fd371bSRob Clark }
40151fd371bSRob Clark EXPORT_SYMBOL(drm_modeset_lock);
40251fd371bSRob Clark
40351fd371bSRob Clark /**
4046f8bcc74SMaarten Lankhorst * drm_modeset_lock_single_interruptible - take a single modeset lock
40551fd371bSRob Clark * @lock: lock to take
40651fd371bSRob Clark *
4076f8bcc74SMaarten Lankhorst * This function behaves as drm_modeset_lock() with a NULL context,
4086f8bcc74SMaarten Lankhorst * but performs interruptible waits.
4096f8bcc74SMaarten Lankhorst *
4106f8bcc74SMaarten Lankhorst * This function returns 0 on success, or -ERESTARTSYS when interrupted.
41151fd371bSRob Clark */
drm_modeset_lock_single_interruptible(struct drm_modeset_lock * lock)4126f8bcc74SMaarten Lankhorst int drm_modeset_lock_single_interruptible(struct drm_modeset_lock *lock)
41351fd371bSRob Clark {
41451fd371bSRob Clark return ww_mutex_lock_interruptible(&lock->mutex, NULL);
41551fd371bSRob Clark }
4166f8bcc74SMaarten Lankhorst EXPORT_SYMBOL(drm_modeset_lock_single_interruptible);
41751fd371bSRob Clark
41851fd371bSRob Clark /**
41951fd371bSRob Clark * drm_modeset_unlock - drop modeset lock
42051fd371bSRob Clark * @lock: lock to release
42151fd371bSRob Clark */
drm_modeset_unlock(struct drm_modeset_lock * lock)42251fd371bSRob Clark void drm_modeset_unlock(struct drm_modeset_lock *lock)
42351fd371bSRob Clark {
42451fd371bSRob Clark list_del_init(&lock->head);
42551fd371bSRob Clark ww_mutex_unlock(&lock->mutex);
42651fd371bSRob Clark }
42751fd371bSRob Clark EXPORT_SYMBOL(drm_modeset_unlock);
42851fd371bSRob Clark
42906eaae46SThierry Reding /**
43006eaae46SThierry Reding * drm_modeset_lock_all_ctx - take all modeset locks
43106eaae46SThierry Reding * @dev: DRM device
43206eaae46SThierry Reding * @ctx: lock acquisition context
43306eaae46SThierry Reding *
43406eaae46SThierry Reding * This function takes all modeset locks, suitable where a more fine-grained
43506eaae46SThierry Reding * scheme isn't (yet) implemented.
43606eaae46SThierry Reding *
437d574528aSDaniel Vetter * Unlike drm_modeset_lock_all(), it doesn't take the &drm_mode_config.mutex
43806eaae46SThierry Reding * since that lock isn't required for modeset state changes. Callers which
43906eaae46SThierry Reding * need to grab that lock too need to do so outside of the acquire context
44006eaae46SThierry Reding * @ctx.
44106eaae46SThierry Reding *
44206eaae46SThierry Reding * Locks acquired with this function should be released by calling the
44306eaae46SThierry Reding * drm_modeset_drop_locks() function on @ctx.
44406eaae46SThierry Reding *
445b7ea04d2SSean Paul * See also: DRM_MODESET_LOCK_ALL_BEGIN() and DRM_MODESET_LOCK_ALL_END()
446b7ea04d2SSean Paul *
44706eaae46SThierry Reding * Returns: 0 on success or a negative error-code on failure.
44806eaae46SThierry Reding */
drm_modeset_lock_all_ctx(struct drm_device * dev,struct drm_modeset_acquire_ctx * ctx)44906eaae46SThierry Reding int drm_modeset_lock_all_ctx(struct drm_device *dev,
45051fd371bSRob Clark struct drm_modeset_acquire_ctx *ctx)
45151fd371bSRob Clark {
452b962a120SRob Clark struct drm_private_obj *privobj;
45351fd371bSRob Clark struct drm_crtc *crtc;
4544d02e2deSDaniel Vetter struct drm_plane *plane;
45506eaae46SThierry Reding int ret;
45606eaae46SThierry Reding
45706eaae46SThierry Reding ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
45806eaae46SThierry Reding if (ret)
45906eaae46SThierry Reding return ret;
46051fd371bSRob Clark
461e4f62546SDaniel Vetter drm_for_each_crtc(crtc, dev) {
46251fd371bSRob Clark ret = drm_modeset_lock(&crtc->mutex, ctx);
46351fd371bSRob Clark if (ret)
46451fd371bSRob Clark return ret;
46551fd371bSRob Clark }
46651fd371bSRob Clark
467e4f62546SDaniel Vetter drm_for_each_plane(plane, dev) {
4684d02e2deSDaniel Vetter ret = drm_modeset_lock(&plane->mutex, ctx);
4694d02e2deSDaniel Vetter if (ret)
4704d02e2deSDaniel Vetter return ret;
4714d02e2deSDaniel Vetter }
4724d02e2deSDaniel Vetter
473b962a120SRob Clark drm_for_each_privobj(privobj, dev) {
474b962a120SRob Clark ret = drm_modeset_lock(&privobj->lock, ctx);
475b962a120SRob Clark if (ret)
476b962a120SRob Clark return ret;
477b962a120SRob Clark }
478b962a120SRob Clark
47951fd371bSRob Clark return 0;
48051fd371bSRob Clark }
48106eaae46SThierry Reding EXPORT_SYMBOL(drm_modeset_lock_all_ctx);
482