Add a new container for fences which internally uses dma_fence_array's to store the fences.
Signed-off-by: Christian König christian.koenig@amd.com --- drivers/dma-buf/dma-resv.c | 221 +++++++++++++++++++++++++++++++++++++ include/linux/dma-resv.h | 49 ++++++++ 2 files changed, 270 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index d3a9a3bb15f0..83033b3e8521 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -33,6 +33,7 @@ */
#include <linux/dma-resv.h> +#include <linux/dma-fence-array.h> #include <linux/export.h>
/** @@ -55,6 +56,226 @@ EXPORT_SYMBOL(reservation_seqcount_class); const char reservation_seqcount_string[] = "reservation_seqcount"; EXPORT_SYMBOL(reservation_seqcount_string);
+static void dma_resv_fences_init(struct dma_resv_fences *fences) +{ + RCU_INIT_POINTER(fences->fence, NULL); + fences->staged = NULL; +} + +static void dma_resv_fences_fini(struct dma_resv_fences *fences) +{ + /* + * This object should be dead and all references must have + * been released to it, so no need to be protected with rcu. + */ + dma_fence_put(rcu_dereference_protected(fences->fence, true)); + dma_fence_array_free(fences->staged); +} + +/** + * dma_resv_fences_reserve - allocate fence slots + * @fences: fences object where we need slots + * @num_fences: number of fence slots we need + * + * Make sure that we have at least @num_fences + all the existing ones free + * slots in the staged dma_fence_array. + * + * Returns -ENOMEM on allocation failure, 0 otherwise. + */ +int dma_resv_fences_reserve(struct dma_resv *obj, + struct dma_resv_fences *fences, + unsigned int num_fences) +{ + struct dma_fence *fence = dma_resv_fences_deref(obj, fences); + struct dma_fence_array *staged, *array; + unsigned int i; + + array = fences->staged; + if (!array) + array = to_dma_fence_array(fence); + + if (array) + num_fences += array->num_fences; + else if (fence) + num_fences += 1; + + staged = fences->staged; + if (staged && dma_fence_array_max_fences(staged) >= num_fences) + return 0; + + staged = dma_fence_array_alloc(num_fences, NULL); + if (!staged) + return -ENOMEM; + + /* Copy over all fences from the old object */ + if (array) { + for (i = 0; i < array->num_fences; ++i) { + struct dma_fence *f = array->fences[i]; + + staged->fences[i] = dma_fence_get(f); + } + staged->num_fences = array->num_fences; + + } else if (fence) { + staged->fences[0] = dma_fence_get(fence); + staged->num_fences = 1; + + } else { + staged->num_fences = 0; + } + + dma_fence_array_free(fences->staged); + fences->staged = staged; + + return 0; +} +EXPORT_SYMBOL(dma_resv_fences_reserve); + +/** + * dma_resv_fences_assign - set the singleton fence + * @fences: fences object where to set the fence + * @fence: singleton fence for the object + * + * Internal helper to assign the signleton fence without grapping a reference. + * If the old fence is a dma_fence_array try to recycle it. + */ +static void dma_resv_fences_assign(struct dma_resv *obj, + struct dma_resv_fences *fences, + struct dma_fence *fence) +{ + struct dma_fence_array *array, *staged; + unsigned int num_fences, i; + struct dma_fence *old; + + old = dma_resv_fences_deref(obj, fences); + rcu_assign_pointer(fences->fence, fence); + + dma_fence_array_free(fences->staged); + fences->staged = NULL; + + /* Try to recycle the old fence array */ + staged = to_dma_fence_array(old); + if (!staged) + goto drop_old; + + array = to_dma_fence_array(fence); + if (array) + num_fences = array->num_fences; + else + num_fences = fence ? 1 : 0; + + if (dma_fence_array_max_fences(staged) < num_fences) + goto drop_old; + + /* Try to drop the last reference */ + if (!dma_fence_array_recycle(staged)) + return; + + /* Make sure the staged array has the latest fences */ + if (array) { + for (i = 0; i < array->num_fences; ++i) { + struct dma_fence *f = array->fences[i]; + + if (f == staged->fences[i]) + continue; + + dma_fence_put(staged->fences[i]); + staged->fences[i] = dma_fence_get(f); + } + for (;i < staged->num_fences; ++i) + dma_fence_put(staged->fences[i]); + staged->num_fences = array->num_fences; + + } else if (fence) { + for (i = 0; i < staged->num_fences; ++i) + dma_fence_put(staged->fences[i]); + staged->fences[0] = dma_fence_get(fence); + staged->num_fences = 1; + } else { + for (i = 0; i < staged->num_fences; ++i) + dma_fence_put(staged->fences[i]); + staged->num_fences = 0; + } + + fences->staged = staged; + return; + +drop_old: + dma_fence_put(old); +} + +/** + * dma_resv_fences_set - set the singleton fence + * @fences: fences object where to set the fence + * @fence: singleton fence for the object + * + * Grabs a reference to the new fence and replaces the current singleton fence + * with a new one. If the old fence is a dma_fence_array try to recycle it. + */ +void dma_resv_fences_set(struct dma_resv *obj, + struct dma_resv_fences *fences, + struct dma_fence *fence) +{ + dma_fence_get(fence); + dma_resv_fences_assign(obj, fences, fence); +} +EXPORT_SYMBOL(dma_resv_fences_set); + +/** + * dma_resv_fences_add - add a fence to the staged fence_array + * @fences: fences object where to add the fence to + * @fence: fence to add + * + * Add a new fence to the staged fence_array. + */ +void dma_resv_fences_add(struct dma_resv_fences *fences, + struct dma_fence *fence) +{ + struct dma_fence_array *staged = fences->staged; + struct dma_fence *old; + unsigned int i; + +#ifndef CONFIG_DEBUG_MUTEXES + for (i = 0; i < staged->num_fences; ++i) { + old = staged->fences[i]; + + if (old->context == fence->context || + dma_fence_is_signaled(old)) { + dma_fence_put(old); + goto replace; + } + } +#endif + + BUG_ON(staged->num_fences >= dma_fence_array_max_fences(staged)); + i = staged->num_fences++; + +replace: + staged->fences[i] = dma_fence_get(fence); +} +EXPORT_SYMBOL(dma_resv_fences_add); + +/** + * dma_resv_fences_commit - commit the staged dma_fence_array + * @fences: fences object where the commit should happen + * + * Commit the fences staged in the dma_fence_array and make them visible to + * other threads. + */ +void dma_resv_fences_commit(struct dma_resv *obj, + struct dma_resv_fences *fences) +{ + struct dma_fence_array *staged = fences->staged; + + if (!staged || !staged->num_fences) + return; + + fences->staged = NULL; + dma_fence_array_init(staged, dma_fence_context_alloc(1), 1, false); + dma_resv_fences_assign(obj, fences, &staged->base); +} +EXPORT_SYMBOL(dma_resv_fences_commit); + /** * dma_resv_list_alloc - allocate fence list * @shared_max: number of fences we need space for diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h index 03b0f95682b0..c70f13fa6789 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -45,10 +45,33 @@ #include <linux/seqlock.h> #include <linux/rcupdate.h>
+struct dma_resv; + extern struct ww_class reservation_ww_class; extern struct lock_class_key reservation_seqcount_class; extern const char reservation_seqcount_string[];
+/** + * struct dma_resv_fences - fences inside a reservation object + * @fence: the current RCU protected singleton fence + * @staged: optional staged dma_fence_array to replace @fence + */ +struct dma_resv_fences { + struct dma_fence __rcu *fence; + struct dma_fence_array *staged; +}; + +int dma_resv_fences_reserve(struct dma_resv *obj, + struct dma_resv_fences *fences, + unsigned int num_fences); +void dma_resv_fences_set(struct dma_resv *obj, + struct dma_resv_fences *fences, + struct dma_fence *fence); +void dma_resv_fences_add(struct dma_resv_fences *fences, + struct dma_fence *fence); +void dma_resv_fences_commit(struct dma_resv *obj, + struct dma_resv_fences *fences); + /** * struct dma_resv_list - a list of shared fences * @rcu: for internal use @@ -80,6 +103,32 @@ struct dma_resv { #define dma_resv_held(obj) lockdep_is_held(&(obj)->lock.base) #define dma_resv_assert_held(obj) lockdep_assert_held(&(obj)->lock.base)
+/** + * dma_resv_fences_deref - get singleton fence + * @obj: the reservation object + * @fences: the fences object + * + * Returns the singleton fence from a resv_fences object. + */ +static inline struct dma_fence * +dma_resv_fences_deref(struct dma_resv *obj, struct dma_resv_fences *fences) +{ + return rcu_dereference_protected(fences->fence, + dma_resv_held(obj)); +} + +/** + * dma_resv_fences_get_rcu - RCU get single fence + * @fences: fences structure where we need to get a reference for + * + * Get a reference to the single fence representing the synchronization. + */ +static inline struct dma_fence * +dma_resv_fences_get_rcu(struct dma_resv_fences *fences) +{ + return dma_fence_get_rcu_safe(&fences->fence); +} + /** * dma_resv_get_list - get the reservation object's * shared fence list, with update-side lock held