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Regard whitespace Rev 5270 → Rev 5271

/drivers/video/drm/drm_modeset_lock.c
35,7 → 35,7
* of extra utility/tracking out of our acquire-ctx. This is provided
* by drm_modeset_lock / drm_modeset_acquire_ctx.
*
* For basic principles of ww_mutex, see: Documentation/ww-mutex-design.txt
* For basic principles of ww_mutex, see: Documentation/locking/ww-mutex-design.txt
*
* The basic usage pattern is to:
*
57,6 → 57,230
 
 
/**
* __drm_modeset_lock_all - internal helper to grab all modeset locks
* @dev: DRM device
* @trylock: trylock mode for atomic contexts
*
* This is a special version of drm_modeset_lock_all() which can also be used in
* atomic contexts. Then @trylock must be set to true.
*
* Returns:
* 0 on success or negative error code on failure.
*/
int __drm_modeset_lock_all(struct drm_device *dev,
bool trylock)
{
struct drm_mode_config *config = &dev->mode_config;
struct drm_modeset_acquire_ctx *ctx;
int ret;
 
ctx = kzalloc(sizeof(*ctx),
trylock ? GFP_ATOMIC : GFP_KERNEL);
if (!ctx)
return -ENOMEM;
 
if (trylock) {
if (!mutex_trylock(&config->mutex))
return -EBUSY;
} else {
mutex_lock(&config->mutex);
}
 
drm_modeset_acquire_init(ctx, 0);
ctx->trylock_only = trylock;
 
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;
 
WARN_ON(config->acquire_ctx);
 
/* now we hold the locks, so now that it is safe, stash the
* ctx for drm_modeset_unlock_all():
*/
config->acquire_ctx = ctx;
 
drm_warn_on_modeset_not_all_locked(dev);
 
return 0;
 
fail:
if (ret == -EDEADLK) {
drm_modeset_backoff(ctx);
goto retry;
}
 
return ret;
}
EXPORT_SYMBOL(__drm_modeset_lock_all);
 
/**
* drm_modeset_lock_all - take all modeset locks
* @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.
*/
void drm_modeset_lock_all(struct drm_device *dev)
{
WARN_ON(__drm_modeset_lock_all(dev, false) != 0);
}
EXPORT_SYMBOL(drm_modeset_lock_all);
 
/**
* drm_modeset_unlock_all - drop all modeset locks
* @dev: device
*
* This function drop all modeset locks taken by drm_modeset_lock_all.
*/
void drm_modeset_unlock_all(struct drm_device *dev)
{
struct drm_mode_config *config = &dev->mode_config;
struct drm_modeset_acquire_ctx *ctx = config->acquire_ctx;
 
if (WARN_ON(!ctx))
return;
 
config->acquire_ctx = NULL;
drm_modeset_drop_locks(ctx);
drm_modeset_acquire_fini(ctx);
 
kfree(ctx);
 
mutex_unlock(&dev->mode_config.mutex);
}
EXPORT_SYMBOL(drm_modeset_unlock_all);
 
/**
* drm_modeset_lock_crtc - lock crtc with hidden acquire ctx for a plane update
* @crtc: DRM CRTC
* @plane: DRM plane to be updated on @crtc
*
* This function locks the given crtc and plane (which should be either the
* primary or cursor plane) using a hidden acquire context. This is necessary so
* that drivers internally using the atomic interfaces can grab further locks
* with the lock acquire context.
*
* Note that @plane can be NULL, e.g. when the cursor support hasn't yet been
* converted to universal planes yet.
*/
void drm_modeset_lock_crtc(struct drm_crtc *crtc,
struct drm_plane *plane)
{
struct drm_modeset_acquire_ctx *ctx;
int ret;
 
ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
if (WARN_ON(!ctx))
return;
 
drm_modeset_acquire_init(ctx, 0);
 
retry:
ret = drm_modeset_lock(&crtc->mutex, ctx);
if (ret)
goto fail;
 
if (plane) {
ret = drm_modeset_lock(&plane->mutex, ctx);
if (ret)
goto fail;
 
if (plane->crtc) {
ret = drm_modeset_lock(&plane->crtc->mutex, ctx);
if (ret)
goto fail;
}
}
 
WARN_ON(crtc->acquire_ctx);
 
/* now we hold the locks, so now that it is safe, stash the
* ctx for drm_modeset_unlock_crtc():
*/
crtc->acquire_ctx = ctx;
 
return;
 
fail:
if (ret == -EDEADLK) {
drm_modeset_backoff(ctx);
goto retry;
}
}
EXPORT_SYMBOL(drm_modeset_lock_crtc);
 
/**
* drm_modeset_legacy_acquire_ctx - find acquire ctx for legacy ioctls
* @crtc: drm crtc
*
* Legacy ioctl operations like cursor updates or page flips only have per-crtc
* locking, and store the acquire ctx in the corresponding crtc. All other
* legacy operations take all locks and use a global acquire context. This
* function grabs the right one.
*/
struct drm_modeset_acquire_ctx *
drm_modeset_legacy_acquire_ctx(struct drm_crtc *crtc)
{
if (crtc->acquire_ctx)
return crtc->acquire_ctx;
 
WARN_ON(!crtc->dev->mode_config.acquire_ctx);
 
return crtc->dev->mode_config.acquire_ctx;
}
EXPORT_SYMBOL(drm_modeset_legacy_acquire_ctx);
 
/**
* drm_modeset_unlock_crtc - drop crtc lock
* @crtc: drm crtc
*
* This drops the crtc lock acquire with drm_modeset_lock_crtc() and all other
* locks acquired through the hidden context.
*/
void drm_modeset_unlock_crtc(struct drm_crtc *crtc)
{
struct drm_modeset_acquire_ctx *ctx = crtc->acquire_ctx;
 
if (WARN_ON(!ctx))
return;
 
crtc->acquire_ctx = NULL;
drm_modeset_drop_locks(ctx);
drm_modeset_acquire_fini(ctx);
 
kfree(ctx);
}
EXPORT_SYMBOL(drm_modeset_unlock_crtc);
 
/**
* drm_warn_on_modeset_not_all_locked - check that all modeset locks are locked
* @dev: device
*
* Useful as a debug assert.
*/
void drm_warn_on_modeset_not_all_locked(struct drm_device *dev)
{
struct drm_crtc *crtc;
 
/* Locking is currently fubar in the panic handler. */
// if (oops_in_progress)
// return;
 
list_for_each_entry(crtc, &dev->mode_config.crtc_list, head)
WARN_ON(!drm_modeset_is_locked(&crtc->mutex));
 
WARN_ON(!drm_modeset_is_locked(&dev->mode_config.connection_mutex));
WARN_ON(!mutex_is_locked(&dev->mode_config.mutex));
}
EXPORT_SYMBOL(drm_warn_on_modeset_not_all_locked);
 
/**
* drm_modeset_acquire_init - initialize acquire context
* @ctx: the acquire context
* @flags: for future
108,7 → 332,12
 
WARN_ON(ctx->contended);
 
if (interruptible && slow) {
if (ctx->trylock_only) {
if (!ww_mutex_trylock(&lock->mutex))
return -EBUSY;
else
return 0;
} else if (interruptible && slow) {
ret = ww_mutex_lock_slow_interruptible(&lock->mutex, &ctx->ww_ctx);
} else if (interruptible) {
ret = ww_mutex_lock_interruptible(&lock->mutex, &ctx->ww_ctx);
226,15 → 455,14
}
EXPORT_SYMBOL(drm_modeset_unlock);
 
/* Temporary.. until we have sufficiently fine grained locking, there
* are a couple scenarios where it is convenient to grab all crtc locks.
* It is planned to remove this:
*/
/* 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)
{
struct drm_mode_config *config = &dev->mode_config;
struct drm_crtc *crtc;
struct drm_plane *plane;
int ret = 0;
 
list_for_each_entry(crtc, &config->crtc_list, head) {
243,6 → 471,12
return ret;
}
 
list_for_each_entry(plane, &config->plane_list, head) {
ret = drm_modeset_lock(&plane->mutex, ctx);
if (ret)
return ret;
}
 
return 0;
}
EXPORT_SYMBOL(drm_modeset_lock_all_crtcs);