On Mon, May 24, 2021 at 03:04:35PM -0500, Jason Ekstrand wrote:
On Fri, May 21, 2021 at 12:48 PM Daniel Vetter daniel@ffwll.ch wrote:
On Thu, May 20, 2021 at 02:00:05PM -0500, Jason Ekstrand wrote:
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
Spurious thing here.
Fixed.
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)Since this is is just internal helper in the .c file we generally don't document it. Maybe small comment if you feel it's worth it.
Sure, I can write LESS documentation. :-P
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
Name doesn't match here.
Fixed.
- @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.
Kernel often encodes this in ERR_PTR so that you don't have to pass a pointer to store the result. Would feel more kerenl-y I think that way. So no result parameter, and on alloc failure you'd return
Done.
return ERR_PTR(-ENOMEM);
- */
+int dma_resv_get_singleton_rcu(struct dma_resv *obj, struct dma_fence *extra,
tbh the _rcu here is confusing. I think _unlocked is the better suffix, maybe we should rename dma_resv_get_fences_rcu too for consistency. The rcu-ness of the lookup isn't leaked to callers at all, so no point giving them a panic.
I can make that change. I'll also include a patch in the next re-send that renames all the _rcu helpers to _unlocked for consistency.
Maybe double-check with Christian König whether he's on board with this bikeshed, but the current _rcu postfix we have in some dma_resv functions really confuses me. -Daniel
--Jason
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);
With the nits addressed:
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
/**
- 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);
-- 2.31.1
-- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch