From: Thierry Reding <treding@xxxxxxxxxx>
This function is like drm_modeset_lock_all(), but it takes the lock
acquisition context as a parameter rather than storing it in the DRM
device's mode_config structure.
Implement drm_modeset_{,un}lock_all() in terms of the new function for
better code reuse, and add a note to the kerneldoc that new code should
use the new functions.
v2: improve kerneldoc
v4: rename drm_modeset_lock_all_crtcs() to drm_modeset_lock_all_ctx()
and take mode_config's .connection_mutex instead of .mutex lock to
avoid lock inversion (Daniel Vetter), use drm_modeset_drop_locks()
which is now the equivalent of drm_modeset_unlock_all_ctx()
Signed-off-by: Thierry Reding <treding@xxxxxxxxxx>
---
drivers/gpu/drm/drm_atomic.c | 3 +-
drivers/gpu/drm/drm_modeset_lock.c | 82 ++++++++++++++++++++++++--------------
include/drm/drm_modeset_lock.h | 4 +-
3 files changed, 56 insertions(+), 33 deletions(-)
diff --git a/drivers/gpu/drm/drm_atomic.c b/drivers/gpu/drm/drm_atomic.c
index 55b4debad79b..4cbe7c07231c 100644
--- a/drivers/gpu/drm/drm_atomic.c
+++ b/drivers/gpu/drm/drm_atomic.c
@@ -1192,8 +1192,7 @@ retry:
state->acquire_ctx);
if (ret)
goto retry;
- ret = drm_modeset_lock_all_crtcs(state->dev,
- state->acquire_ctx);
+ ret = drm_modeset_lock_all_ctx(state->dev, state->acquire_ctx);
if (ret)
goto retry;
}
diff --git a/drivers/gpu/drm/drm_modeset_lock.c b/drivers/gpu/drm/drm_modeset_lock.c
index 6675b1428410..341158c92027 100644
--- a/drivers/gpu/drm/drm_modeset_lock.c
+++ b/drivers/gpu/drm/drm_modeset_lock.c
@@ -57,11 +57,18 @@
/**
* drm_modeset_lock_all - take all modeset locks
- * @dev: drm device
+ * @dev: DRM device
*
* This function takes all modeset locks, suitable where a more fine-grained
- * scheme isn't (yet) implemented. Locks must be dropped with
- * drm_modeset_unlock_all.
+ * scheme isn't (yet) implemented. Locks must be dropped by calling the
+ * drm_modeset_unlock_all() function.
+ *
+ * This function is deprecated. It allocates a lock acquisition context and
+ * stores it in the DRM device's ->mode_config. This facilitate conversion of
+ * existing code because it removes the need to manually deal with the
+ * acquisition context, but it is also brittle because the context is global
+ * and care must be taken not to nest calls. New code should use the
+ * drm_modeset_lock_all_ctx() function and pass in the context explicitly.
*/
void drm_modeset_lock_all(struct drm_device *dev)
{
@@ -78,39 +85,43 @@ void drm_modeset_lock_all(struct drm_device *dev)
drm_modeset_acquire_init(ctx, 0);
retry:
- ret = drm_modeset_lock(&config->connection_mutex, ctx);
- if (ret)
- goto fail;
- ret = drm_modeset_lock_all_crtcs(dev, ctx);
- if (ret)
- goto fail;
+ ret = drm_modeset_lock_all_ctx(dev, ctx);
+ if (ret < 0) {
+ if (ret == -EDEADLK) {
+ drm_modeset_backoff(ctx);
+ goto retry;
+ }
+
+ drm_modeset_acquire_fini(ctx);
+ kfree(ctx);
+ return;
+ }
WARN_ON(config->acquire_ctx);
- /* now we hold the locks, so now that it is safe, stash the
- * ctx for drm_modeset_unlock_all():
+ /*
+ * We hold the locks now, so it is safe to stash the acquisition
+ * context for drm_modeset_unlock_all().
*/
config->acquire_ctx = ctx;
drm_warn_on_modeset_not_all_locked(dev);
-
- return;
-
-fail:
- if (ret == -EDEADLK) {
- drm_modeset_backoff(ctx);
- goto retry;
- }
-
- kfree(ctx);
}
EXPORT_SYMBOL(drm_modeset_lock_all);
/**
* drm_modeset_unlock_all - drop all modeset locks
- * @dev: device
+ * @dev: DRM device
+ *
+ * This function drops all modeset locks taken by a previous call to the
+ * drm_modeset_lock_all() function.
*
- * This function drop all modeset locks taken by drm_modeset_lock_all.
+ * This function is deprecated. It uses the lock acquisition context stored
+ * in the DRM device's ->mode_config. This facilitates conversion of existing
+ * code because it removes the need to manually deal with the acquisition
+ * context, but it is also brittle because the context is global and care must
+ * be taken not to nest calls. New code should pass the acquisition context
+ * directly to the drm_modeset_drop_locks() function.
*/
void drm_modeset_unlock_all(struct drm_device *dev)
{
@@ -431,14 +442,27 @@ void drm_modeset_unlock(struct drm_modeset_lock *lock)
}
EXPORT_SYMBOL(drm_modeset_unlock);
-/* In some legacy codepaths it's convenient to just grab all the crtc and plane
- * related locks. */
-int drm_modeset_lock_all_crtcs(struct drm_device *dev,
- struct drm_modeset_acquire_ctx *ctx)
+/**
+ * drm_modeset_lock_all_ctx - take all modeset locks
+ * @dev: DRM device
+ * @ctx: lock acquisition context
+ *
+ * This function takes all modeset locks, suitable where a more fine-grained
+ * scheme isn't (yet) implemented. Locks must be dropped by calling the
+ * drm_modeset_drop_locks() function.
+ *
+ * Returns: 0 on success or a negative error-code on failure.
+ */
+int drm_modeset_lock_all_ctx(struct drm_device *dev,
+ struct drm_modeset_acquire_ctx *ctx)
{
struct drm_crtc *crtc;
struct drm_plane *plane;
- int ret = 0;
+ int ret;
+
+ ret = drm_modeset_lock(&dev->mode_config.connection_mutex, ctx);
+ if (ret)
+ return ret;
drm_for_each_crtc(crtc, dev) {
ret = drm_modeset_lock(&crtc->mutex, ctx);
@@ -454,4 +478,4 @@ int drm_modeset_lock_all_crtcs(struct drm_device *dev,
return 0;
}
-EXPORT_SYMBOL(drm_modeset_lock_all_crtcs);
+EXPORT_SYMBOL(drm_modeset_lock_all_ctx);
diff --git a/include/drm/drm_modeset_lock.h b/include/drm/drm_modeset_lock.h
index 94938d89347c..c5576fbcb909 100644
--- a/include/drm/drm_modeset_lock.h
+++ b/include/drm/drm_modeset_lock.h
@@ -138,7 +138,7 @@ void drm_warn_on_modeset_not_all_locked(struct drm_device *dev);
struct drm_modeset_acquire_ctx *
drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc);
-int drm_modeset_lock_all_crtcs(struct drm_device *dev,
- struct drm_modeset_acquire_ctx *ctx);
+int drm_modeset_lock_all_ctx(struct drm_device *dev,
+ struct drm_modeset_acquire_ctx *ctx);
#endif /* DRM_MODESET_LOCK_H_ */
--
2.5.0
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