diff options
Diffstat (limited to 'drivers/dma-buf/dma-resv.c')
| -rw-r--r-- | drivers/dma-buf/dma-resv.c | 142 |
1 files changed, 122 insertions, 20 deletions
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index b51416405e86..8c650b96357a 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -34,6 +34,7 @@ */ #include <linux/dma-resv.h> +#include <linux/dma-fence-array.h> #include <linux/export.h> #include <linux/mm.h> #include <linux/sched/mm.h> @@ -56,6 +57,12 @@ DEFINE_WD_CLASS(reservation_ww_class); EXPORT_SYMBOL(reservation_ww_class); +struct dma_resv_list { + struct rcu_head rcu; + u32 shared_count, shared_max; + struct dma_fence __rcu *shared[]; +}; + /** * dma_resv_list_alloc - allocate fence list * @shared_max: number of fences we need space for @@ -133,8 +140,19 @@ void dma_resv_fini(struct dma_resv *obj) } EXPORT_SYMBOL(dma_resv_fini); +static inline struct dma_fence * +dma_resv_excl_fence(struct dma_resv *obj) +{ + return rcu_dereference_check(obj->fence_excl, dma_resv_held(obj)); +} + +static inline struct dma_resv_list *dma_resv_shared_list(struct dma_resv *obj) +{ + return rcu_dereference_check(obj->fence, dma_resv_held(obj)); +} + /** - * dma_resv_reserve_shared - Reserve space to add shared fences to + * dma_resv_reserve_fences - Reserve space to add shared fences to * a dma_resv. * @obj: reservation object * @num_fences: number of fences we want to add @@ -149,7 +167,7 @@ EXPORT_SYMBOL(dma_resv_fini); * RETURNS * Zero for success, or -errno */ -int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences) +int dma_resv_reserve_fences(struct dma_resv *obj, unsigned int num_fences) { struct dma_resv_list *old, *new; unsigned int i, j, k, max; @@ -212,7 +230,7 @@ int dma_resv_reserve_shared(struct dma_resv *obj, unsigned int num_fences) return 0; } -EXPORT_SYMBOL(dma_resv_reserve_shared); +EXPORT_SYMBOL(dma_resv_reserve_fences); #ifdef CONFIG_DEBUG_MUTEXES /** @@ -220,7 +238,7 @@ EXPORT_SYMBOL(dma_resv_reserve_shared); * @obj: the dma_resv object to reset * * Reset the number of pre-reserved shared slots to test that drivers do - * correct slot allocation using dma_resv_reserve_shared(). See also + * correct slot allocation using dma_resv_reserve_fences(). See also * &dma_resv_list.shared_max. */ void dma_resv_reset_shared_max(struct dma_resv *obj) @@ -242,7 +260,7 @@ EXPORT_SYMBOL(dma_resv_reset_shared_max); * @fence: the shared fence to add * * Add a fence to a shared slot, @obj must be locked with dma_resv_lock(), and - * dma_resv_reserve_shared() has been called. + * dma_resv_reserve_fences() has been called. * * See also &dma_resv.fence for a discussion of the semantics. */ @@ -290,40 +308,71 @@ replace: EXPORT_SYMBOL(dma_resv_add_shared_fence); /** + * dma_resv_replace_fences - replace fences in the dma_resv obj + * @obj: the reservation object + * @context: the context of the fences to replace + * @replacement: the new fence to use instead + * + * Replace fences with a specified context with a new fence. Only valid if the + * operation represented by the original fence has no longer access to the + * resources represented by the dma_resv object when the new fence completes. + * + * And example for using this is replacing a preemption fence with a page table + * update fence which makes the resource inaccessible. + */ +void dma_resv_replace_fences(struct dma_resv *obj, uint64_t context, + struct dma_fence *replacement) +{ + struct dma_resv_list *list; + struct dma_fence *old; + unsigned int i; + + dma_resv_assert_held(obj); + + write_seqcount_begin(&obj->seq); + + old = dma_resv_excl_fence(obj); + if (old->context == context) { + RCU_INIT_POINTER(obj->fence_excl, dma_fence_get(replacement)); + dma_fence_put(old); + } + + list = dma_resv_shared_list(obj); + for (i = 0; list && i < list->shared_count; ++i) { + old = rcu_dereference_protected(list->shared[i], + dma_resv_held(obj)); + if (old->context != context) + continue; + + rcu_assign_pointer(list->shared[i], dma_fence_get(replacement)); + dma_fence_put(old); + } + + write_seqcount_end(&obj->seq); +} +EXPORT_SYMBOL(dma_resv_replace_fences); + +/** * dma_resv_add_excl_fence - Add an exclusive fence. * @obj: the reservation object * @fence: the exclusive fence to add * * Add a fence to the exclusive slot. @obj must be locked with dma_resv_lock(). - * Note that this function replaces all fences attached to @obj, see also - * &dma_resv.fence_excl for a discussion of the semantics. + * See also &dma_resv.fence_excl for a discussion of the semantics. */ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence) { struct dma_fence *old_fence = dma_resv_excl_fence(obj); - struct dma_resv_list *old; - u32 i = 0; dma_resv_assert_held(obj); - old = dma_resv_shared_list(obj); - if (old) - i = old->shared_count; - dma_fence_get(fence); write_seqcount_begin(&obj->seq); /* write_seqcount_begin provides the necessary memory barrier */ RCU_INIT_POINTER(obj->fence_excl, fence); - if (old) - old->shared_count = 0; write_seqcount_end(&obj->seq); - /* inplace update, no shared fences */ - while (i--) - dma_fence_put(rcu_dereference_protected(old->shared[i], - dma_resv_held(obj))); - dma_fence_put(old_fence); } EXPORT_SYMBOL(dma_resv_add_excl_fence); @@ -595,6 +644,59 @@ int dma_resv_get_fences(struct dma_resv *obj, bool write, EXPORT_SYMBOL_GPL(dma_resv_get_fences); /** + * dma_resv_get_singleton - Get a single fence for all the fences + * @obj: the reservation object + * @write: true if we should return all fences + * @fence: the resulting fence + * + * Get a single fence representing all the fences inside the resv object. + * Returns either 0 for success or -ENOMEM. + * + * Warning: This can't be used like this when adding the fence back to the resv + * object since that can lead to stack corruption when finalizing the + * dma_fence_array. + * + * Returns 0 on success and negative error values on failure. + */ +int dma_resv_get_singleton(struct dma_resv *obj, bool write, + struct dma_fence **fence) +{ + struct dma_fence_array *array; + struct dma_fence **fences; + unsigned count; + int r; + + r = dma_resv_get_fences(obj, write, &count, &fences); + if (r) + return r; + + if (count == 0) { + *fence = NULL; + return 0; + } + + if (count == 1) { + *fence = fences[0]; + kfree(fences); + return 0; + } + + array = dma_fence_array_create(count, fences, + dma_fence_context_alloc(1), + 1, false); + if (!array) { + while (count--) + dma_fence_put(fences[count]); + kfree(fences); + return -ENOMEM; + } + + *fence = &array->base; + return 0; +} +EXPORT_SYMBOL_GPL(dma_resv_get_singleton); + +/** * dma_resv_wait_timeout - Wait on reservation's objects * shared and/or exclusive fences. * @obj: the reservation object |