This should be squashed into the relevant later patches that start to
use this.
Signed-off-by: Daniel Vetter <daniel.vetter at ffwll.ch>
---
drivers/gpu/drm/drm_crtc.c | 4 +-
drivers/gpu/drm/drm_modeset_lock.c | 72 ++++++++++++++++++++++++------------
drivers/gpu/drm/i915/intel_display.c | 3 +-
include/drm/drm_modeset_lock.h | 41 +++++++++++++++++++-
include/uapi/drm/drm_mode.h | 3 ++
5 files changed, 95 insertions(+), 28 deletions(-)
diff --git a/drivers/gpu/drm/drm_crtc.c b/drivers/gpu/drm/drm_crtc.c
index 9e826aa5fc5c..cf622f6de07c 100644
--- a/drivers/gpu/drm/drm_crtc.c
+++ b/drivers/gpu/drm/drm_crtc.c
@@ -39,7 +39,6 @@
#include <drm/drm_fourcc.h>
#include <drm/drm_modeset_lock.h>
-#include "drm_crtc_internal.h"
/**
* drm_modeset_lock_all - take all modeset locks
@@ -61,7 +60,7 @@ void drm_modeset_lock_all(struct drm_device *dev)
mutex_lock(&config->mutex);
- drm_modeset_acquire_init(ctx);
+ drm_modeset_acquire_init(ctx, false, false);
retry:
ret = drm_modeset_lock(&config->connection_mutex, ctx);
@@ -106,6 +105,7 @@ void drm_modeset_unlock_all(struct drm_device *dev)
config->acquire_ctx = NULL;
drm_modeset_drop_locks(ctx);
+ ww_acquire_fini(&ctx->ww_ctx);
drm_modeset_acquire_fini(ctx);
kfree(ctx);
diff --git a/drivers/gpu/drm/drm_modeset_lock.c
b/drivers/gpu/drm/drm_modeset_lock.c
index 81607ccebd89..6580d6ce8f63 100644
--- a/drivers/gpu/drm/drm_modeset_lock.c
+++ b/drivers/gpu/drm/drm_modeset_lock.c
@@ -26,21 +26,32 @@
#include <drm/drm_modeset_lock.h>
-void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx)
+void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
+ bool nolock, bool nonblock)
{
ww_acquire_init(&ctx->ww_ctx, &crtc_ww_class);
INIT_LIST_HEAD(&ctx->locked);
+ mutex_init(&ctx->mutex);
+ ctx->nolock = nolock;
+ ctx->nonblock = nonblock;
}
EXPORT_SYMBOL(drm_modeset_acquire_init);
void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx)
{
- ww_acquire_fini(&ctx->ww_ctx);
+ WARN_ON(ctx->contended);
+ /*
+ * NOTE: it is intentional that ww_acquire_fini() is not called
+ * here.. due to the way lock handover works in drm_atomic
+ */
+ mutex_destroy(&ctx->mutex);
}
EXPORT_SYMBOL(drm_modeset_acquire_fini);
void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx)
{
+ WARN_ON(ctx->contended);
+ mutex_lock(&ctx->mutex);
while (!list_empty(&ctx->locked)) {
struct drm_modeset_lock *lock;
@@ -49,31 +60,45 @@ void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx
*ctx)
drm_modeset_unlock(lock);
}
+ mutex_unlock(&ctx->mutex);
}
EXPORT_SYMBOL(drm_modeset_drop_locks);
static int modeset_lock(struct drm_modeset_lock *lock,
- struct drm_modeset_acquire_ctx *ctx,
- bool interruptible)
+ struct drm_modeset_acquire_ctx *ctx,
+ bool interruptible, bool slow)
{
int ret;
+ if (ctx->nolock)
+ return 0;
+
+ WARN_ON(ctx->frozen); /* all locks should be held by now! */
+ WARN_ON(ctx->contended);
+
+retry:
if (interruptible) {
ret = ww_mutex_lock_interruptible(&lock->mutex, &ctx->ww_ctx);
+ } else if (slow) {
+ ww_mutex_lock_slow(&lock->mutex, &ctx->ww_ctx);
+ ret = 0;
} else {
ret = ww_mutex_lock(&lock->mutex, &ctx->ww_ctx);
}
-
- if (ret == 0) {
+ if (!ret) {
+ if (lock->atomic_pending) {
+ /* some other pending update with dropped locks */
+ ww_mutex_unlock(&lock->mutex);
+ if (ctx->nonblock)
+ return -EBUSY;
+ wait_event(lock->event, !lock->atomic_pending);
+ goto retry;
+ }
+ lock->atomic_pending = true;
+ WARN_ON(!list_empty(&lock->head));
list_add(&lock->head, &ctx->locked);
} else if (ret == -EALREADY) {
- /*
- * We already hold the lock. This is only fine if it's the lock
- * we've contended on.
- */
- WARN_ON(ctx->contended != lock);
- ctx->contended = NULL;
-
+ /* we already hold the lock.. this is fine */
ret = 0;
} else if (ret == -EDEADLK) {
ctx->contended = lock;
@@ -84,19 +109,18 @@ static int modeset_lock(struct drm_modeset_lock *lock,
void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx)
{
- drm_modeset_drop_locks(ctx);
+ struct drm_modeset_lock *contended = ctx->contended;
- ww_mutex_lock_slow(&ctx->contended->mutex, ctx);
-}
-EXPORT_SYMBOL(drm_modeset_backoff);
+ ctx->contended = NULL;
+
+ if (WARN_ON(!contended))
+ return;
-void drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx)
-{
drm_modeset_drop_locks(ctx);
- ww_mutex_lock_slow(&ctx->contended->mutex, ctx);
+ modeset_lock(contended, ctx, false, true);
}
-EXPORT_SYMBOL(drm_modeset_backoff_interruptible);
+EXPORT_SYMBOL(drm_modeset_backoff);
/**
* drm_modeset_lock - take modeset lock
@@ -112,7 +136,7 @@ int drm_modeset_lock(struct drm_modeset_lock *lock,
struct drm_modeset_acquire_ctx *ctx)
{
if (ctx)
- return modeset_lock(lock, ctx, false);
+ return modeset_lock(lock, ctx, false, false);
ww_mutex_lock(&lock->mutex, NULL);
return 0;
@@ -123,7 +147,7 @@ int drm_modeset_lock_interruptible(struct drm_modeset_lock
*lock,
struct drm_modeset_acquire_ctx *ctx)
{
if (ctx)
- return modeset_lock(lock, ctx, true);
+ return modeset_lock(lock, ctx, true, false);
return ww_mutex_lock_interruptible(&lock->mutex, NULL);
}
@@ -136,7 +160,9 @@ EXPORT_SYMBOL(drm_modeset_lock_interruptible);
void drm_modeset_unlock(struct drm_modeset_lock *lock)
{
list_del_init(&lock->head);
+ lock->atomic_pending = false;
ww_mutex_unlock(&lock->mutex);
+ wake_up_all(&lock->event);
}
EXPORT_SYMBOL(drm_modeset_unlock);
diff --git a/drivers/gpu/drm/i915/intel_display.c
b/drivers/gpu/drm/i915/intel_display.c
index 9d12e3e15dfa..ba6cbbbfe596 100644
--- a/drivers/gpu/drm/i915/intel_display.c
+++ b/drivers/gpu/drm/i915/intel_display.c
@@ -7990,7 +7990,7 @@ bool intel_get_load_detect_pipe(struct drm_connector
*connector,
connector->base.id, drm_get_connector_name(connector),
encoder->base.id, drm_get_encoder_name(encoder));
- drm_modeset_acquire_init(ctx);
+ drm_modeset_acquire_init(ctx, false, false);
retry:
ret = drm_modeset_lock(&config->connection_mutex, ctx);
@@ -8103,6 +8103,7 @@ fail_unlock:
}
drm_modeset_drop_locks(ctx);
+ ww_acquire_fini(&ctx->ww_ctx);
drm_modeset_acquire_fini(ctx);
return false;
diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
index e67fb815b610..2630da3ef1b4 100644
--- a/include/drm/drm_modeset_lock.h
+++ b/include/drm/drm_modeset_lock.h
@@ -32,6 +32,15 @@ struct drm_modeset_acquire_ctx {
struct ww_acquire_ctx ww_ctx;
+ bool nolock : 1;
+ bool nonblock : 1;
+
+ /* just for debugging, the context is 'frozen' in drm_atomic_check()
+ * to catch anyone who might be trying to acquire a lock after it is
+ * too late.
+ */
+ bool frozen : 1;
+
/* contended lock: if a lock is contended you should only call
* drm_modeset_backoff() which drops locks and slow-locks the
* contended lock.
@@ -40,6 +49,16 @@ struct drm_modeset_acquire_ctx {
/* list of 'struct drm_modeset_lock': */
struct list_head locked;
+
+ /* currently simply for protecting against 'locked' list manipulation
+ * between original thread calling atomic->end() and driver thread
+ * calling back drm_atomic_commit_unlocked().
+ *
+ * Other spots are sufficiently synchronized by virtue of holding
+ * the lock's ww_mutex. But during the lock/resource hand-over to the
+ * driver thread (drop_locks()/grab_locks()), we cannot rely on this.
+ */
+ struct mutex mutex;
};
/**
@@ -59,24 +78,42 @@ struct drm_modeset_lock {
struct ww_mutex mutex;
/**
+ * Are we busy (pending asynchronous/NONBLOCK update)? Any further
+ * asynchronous update will return -EBUSY if it also needs to acquire
+ * this lock. While a synchronous update will block until the pending
+ * async update completes.
+ *
+ * Drivers must ensure the update is completed before sending vblank
+ * event to userspace. Typically this just means don't send event
+ * before drm_atomic_commit_unlocked() returns.
+ */
+ bool atomic_pending;
+
+ /**
* Resources that are locked as part of an atomic update are added
* to a list (so we know what to unlock at the end).
*/
struct list_head head;
+
+ /**
+ * For waiting on atomic_pending locks, if not a NONBLOCK operation.
+ */
+ wait_queue_head_t event;
};
extern struct ww_class crtc_ww_class;
-void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx);
+void drm_modeset_acquire_init(struct drm_modeset_acquire_ctx *ctx,
+ bool nolock, bool nonblock);
void drm_modeset_acquire_fini(struct drm_modeset_acquire_ctx *ctx);
void drm_modeset_drop_locks(struct drm_modeset_acquire_ctx *ctx);
void drm_modeset_backoff(struct drm_modeset_acquire_ctx *ctx);
-void drm_modeset_backoff_interruptible(struct drm_modeset_acquire_ctx *ctx);
static inline void drm_modeset_lock_init(struct drm_modeset_lock *lock)
{
ww_mutex_init(&lock->mutex, &crtc_ww_class);
INIT_LIST_HEAD(&lock->head);
+ init_waitqueue_head(&lock->event);
}
static inline void drm_modeset_lock_fini(struct drm_modeset_lock *lock)
diff --git a/include/uapi/drm/drm_mode.h b/include/uapi/drm/drm_mode.h
index ded505ede145..6421edcd27a8 100644
--- a/include/uapi/drm/drm_mode.h
+++ b/include/uapi/drm/drm_mode.h
@@ -511,4 +511,7 @@ struct drm_mode_destroy_dumb {
uint32_t handle;
};
+#define DRM_MODE_ATOMIC_NONBLOCK 0x0200
+#define DRM_MODE_ATOMIC_NOLOCK 0x8000 /* only used internally */
+
#endif
--
1.9.2
