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
v5 (Daniel Vetter): - Rename from _rcu to _unlocked since it doesn't leak RCU details to the caller - Fix docs - Use ERR_PTR for error handling rather than an output dma_fence**
v5 (Jason Ekstrand): - Drop the extra fence param and leave that to a separate patch
v6 (Jason Ekstrand): - Rename to dma_resv_get_singleton to match the new naming convention for dma_resv helpers which work without taking a lock.
Signed-off-by: Jason Ekstrand jason@jlekstrand.net Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch Cc: Christian König christian.koenig@amd.com Cc: Maarten Lankhorst maarten.lankhorst@linux.intel.com --- drivers/dma-buf/dma-resv.c | 91 ++++++++++++++++++++++++++++++++++++++ include/linux/dma-resv.h | 1 + 2 files changed, 92 insertions(+)
diff --git a/drivers/dma-buf/dma-resv.c b/drivers/dma-buf/dma-resv.c index f26c71747d43a..1b26aa7e5d81c 100644 --- a/drivers/dma-buf/dma-resv.c +++ b/drivers/dma-buf/dma-resv.c @@ -34,6 +34,8 @@ */
#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> @@ -50,6 +52,10 @@ * write-side updates. */
+#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);
@@ -495,6 +501,91 @@ int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl, } EXPORT_SYMBOL_GPL(dma_resv_get_fences);
+/** + * dma_resv_get_singleton - get a single fence for the dma_resv object + * @obj: the reservation object + * + * 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 + * The singleton dma_fence on success or an ERR_PTR on failure + */ +struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj) +{ + struct dma_fence *result, **resv_fences, *fence, *chain, **fences; + struct dma_fence_array *array; + unsigned int num_resv_fences, num_fences; + unsigned int err, i, j; + + err = dma_resv_get_fences(obj, NULL, &num_resv_fences, &resv_fences); + if (err) + return ERR_PTR(err); + + if (num_resv_fences == 0) + return NULL; + + num_fences = 0; + result = NULL; + + 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 (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 = ERR_PTR(-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 (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 = ERR_PTR(-ENOMEM); + while (num_fences--) + dma_fence_put(fences[num_fences]); + kfree(fences); + } + +put_resv_fences: + while (num_resv_fences--) + dma_fence_put(resv_fences[num_resv_fences]); + kfree(resv_fences); + + return result; +} +EXPORT_SYMBOL_GPL(dma_resv_get_singleton); + /** * dma_resv_wait_timeout - 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 562b885cf9c3d..d60982975a786 100644 --- a/include/linux/dma-resv.h +++ b/include/linux/dma-resv.h @@ -275,6 +275,7 @@ void dma_resv_add_excl_fence(struct dma_resv *obj, struct dma_fence *fence); int dma_resv_get_fences(struct dma_resv *obj, struct dma_fence **pfence_excl, unsigned *pshared_count, struct dma_fence ***pshared); int dma_resv_copy_fences(struct dma_resv *dst, struct dma_resv *src); +struct dma_fence *dma_resv_get_singleton(struct dma_resv *obj); long dma_resv_wait_timeout(struct dma_resv *obj, bool wait_all, bool intr, unsigned long timeout); bool dma_resv_test_signaled(struct dma_resv *obj, bool test_all);