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drm: Implement drm_modeset_lock_all_ctx() 

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()
v5: do not take the dev->mode_config.connection_mutex in
    drm_atomic_legacy_backoff() since drm_modeset_lock_all_ctx()
    already keeps it, enhance kerneldoc for drm_modeset_lock_all_ctx()
    (Daniel Vetter)

Signed-off-by: Thierry Reding <treding@nvidia.com>
Link: http://patchwork.freedesktop.org/patch/msgid/1449075005-13937-1-git-send-email-thierry.reding@gmail.com
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
This commit is contained in:
Thierry Reding 2015-12-02 17:50:03 +01:00 committed by Daniel Vetter
parent 737292a3c0
commit 06eaae4638
3 changed files with 63 additions and 37 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
drivers/gpu/drm/drm_atomic.c
View File

@ -1188,12 +1188,7 @@ void drm_atomic_legacy_backoff(struct drm_atomic_state *state)
retry:
drm_modeset_backoff(state->acquire_ctx);
ret = drm_modeset_lock(&state->dev->mode_config.connection_mutex,
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;
}

89
drivers/gpu/drm/drm_modeset_lock.c
View File

@ -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 drop all modeset locks taken by drm_modeset_lock_all.
* This function drops all modeset locks taken by a previous call to the
* drm_modeset_lock_all() function.
*
* 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 +442,34 @@ 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.
*
* Unlike drm_modeset_lock_all(), it doesn't take the dev->mode_config.mutex
* since that lock isn't required for modeset state changes. Callers which
* need to grab that lock too need to do so outside of the acquire context
* @ctx.
*
* Locks acquired with this function should be released by calling the
* drm_modeset_drop_locks() function on @ctx.
*
* 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 +485,4 @@ 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);

4
include/drm/drm_modeset_lock.h
View File

@ -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_ */