Add a helper function to get a single fence representing all fences in a dma_resv object.
This fence is either the only one in the object or all not signaled fences of the object in a flatted out dma_fence_array.
v2 (Jason Ekstrand): - Take reference of fences both for creating the dma_fence_array and in the case where we return one fence. - Handle the case where dma_resv_get_list() returns NULL
v3 (Jason Ekstrand): - Add an _rcu suffix because it is read-only - Rewrite to use dma_resv_get_fences_rcu so it's RCU-safe - Add an EXPORT_SYMBOL_GPL declaration - Re-author the patch to Jason since very little is left of Christian König's original patch - Remove the extra fence argument
v4 (Jason Ekstrand): - Restore the extra fence argument
Signed-off-by: Jason Ekstrand jason@jlekstrand.net
get_singleton --- drivers/dma-buf/dma-resv.c | 122 +++++++++++++++++++++++++++++++++++++ include/linux/dma-resv.h | 3 + 2 files changed, 125 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index 6ddbeb5dfbf65..25995fc15c370 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -33,6 +33,8 @@ */
#include <linux/dma-resv.h> +#include <linux/dma-fence-chain.h> +#include <linux/dma-fence-array.h> #include <linux/export.h> #include <linux/mm.h> #include <linux/sched/mm.h> @@ -49,6 +51,19 @@ * write-side updates. */
+/** + * dma_fence_deep_dive_for_each - deep dive into the fence containers + * @fence: resulting fence + * @chain: variable for a dma_fence_chain + * @index: index into a dma_fence_array + * @head: starting point + * + * Helper to deep dive into the fence containers for flattening them. + */ +#define dma_fence_deep_dive_for_each(fence, chain, index, head) \ + dma_fence_chain_for_each(chain, head) \ + dma_fence_array_for_each(fence, index, chain) + DEFINE_WD_CLASS(reservation_ww_class); EXPORT_SYMBOL(reservation_ww_class);
@@ -517,6 +532,113 @@ int dma_resv_get_fences_rcu(struct dma_resv *obj, } EXPORT_SYMBOL_GPL(dma_resv_get_fences_rcu);
+/** + * dma_resv_get_singleton - get a single fence for the dma_resv object + * @obj: the reservation object + * @extra: extra fence to add to the resulting array + * @result: resulting dma_fence + * + * Get a single fence representing all unsignaled fences in the dma_resv object + * plus the given extra fence. If we got only one fence return a new + * reference to that, otherwise return a dma_fence_array object. + * + * RETURNS + * Returns -NOMEM if allocations fail, zero otherwise. + */ +int dma_resv_get_singleton_rcu(struct dma_resv *obj, struct dma_fence *extra, + struct dma_fence **result) +{ + struct dma_fence **resv_fences, *fence, *chain, **fences; + struct dma_fence_array *array; + unsigned int num_resv_fences, num_fences; + unsigned int ret, i, j; + + ret = dma_resv_get_fences_rcu(obj, NULL, &num_resv_fences, &resv_fences); + if (ret) + return ret; + + num_fences = 0; + *result = NULL; + + if (num_resv_fences == 0 && !extra) + return 0; + + for (i = 0; i < num_resv_fences; ++i) { + dma_fence_deep_dive_for_each(fence, chain, j, resv_fences[i]) { + if (dma_fence_is_signaled(fence)) + continue; + + *result = fence; + ++num_fences; + } + } + + if (extra) { + dma_fence_deep_dive_for_each(fence, chain, j, extra) { + if (dma_fence_is_signaled(fence)) + continue; + + *result = fence; + ++num_fences; + } + } + + if (num_fences <= 1) { + *result = dma_fence_get(*result); + goto put_resv_fences; + } + + fences = kmalloc_array(num_fences, sizeof(struct dma_fence*), + GFP_KERNEL); + if (!fences) { + *result = NULL; + ret = -ENOMEM; + goto put_resv_fences; + } + + num_fences = 0; + for (i = 0; i < num_resv_fences; ++i) { + dma_fence_deep_dive_for_each(fence, chain, j, resv_fences[i]) { + if (!dma_fence_is_signaled(fence)) + fences[num_fences++] = dma_fence_get(fence); + } + } + + if (extra) { + dma_fence_deep_dive_for_each(fence, chain, j, extra) { + if (dma_fence_is_signaled(fence)) + fences[num_fences++] = dma_fence_get(fence); + } + } + + if (num_fences <= 1) { + *result = num_fences ? fences[0] : NULL; + kfree(fences); + goto put_resv_fences; + } + + array = dma_fence_array_create(num_fences, fences, + dma_fence_context_alloc(1), + 1, false); + if (array) { + *result = &array->base; + } else { + *result = NULL; + while (num_fences--) + dma_fence_put(fences[num_fences]); + kfree(fences); + ret = -ENOMEM; + } + +put_resv_fences: + while (num_resv_fences--) + dma_fence_put(resv_fences[num_resv_fences]); + kfree(resv_fences); + + return ret; +} +EXPORT_SYMBOL_GPL(dma_resv_get_singleton_rcu); + /** * dma_resv_wait_timeout_rcu - Wait on reservation's objects * shared and/or exclusive fences. diff --git a/include/linux/dma-resv.h b/include/linux/dma-resv.h index d44a77e8a7e34..d49ca263e78b4 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -285,6 +285,9 @@ int dma_resv_get_fences_rcu(struct dma_resv *obj,
int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src);
+int dma_resv_get_singleton_rcu(struct dma_resv *obj, struct dma_fence *extra, + struct dma_fence **result); + long dma_resv_wait_timeout_rcu(struct dma_resv *obj, bool wait_all, bool intr, unsigned long timeout);