[PATCH 2/6] dma-buf: Add dma_resv_get_singleton (v6)
Christian König
christian.koenig at amd.com
Fri Jun 11 07:11:27 UTC 2021
Am 10.06.21 um 23:09 schrieb Jason Ekstrand:
> 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 at jlekstrand.net>
> Reviewed-by: Daniel Vetter <daniel.vetter at ffwll.ch>
Reviewed-by: Christian König <christian.koenig at amd.com>
> Cc: Christian König <christian.koenig at amd.com>
> Cc: Maarten Lankhorst <maarten.lankhorst at 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);
More information about the dri-devel
mailing list