dma-buf provides an interfaces for receiving notifications from DMA
hardware. kfence provides a useful interface for collecting such fences
and combining them with other events.
Signed-off-by: Chris Wilson <chris@xxxxxxxxxxxxxxxxxx>
Cc: Sumit Semwal <sumit.semwal@xxxxxxxxxx>
Cc: Shuah Khan <shuahkh@xxxxxxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: Daniel Vetter <daniel.vetter@xxxxxxxx>
Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Cc: Ingo Molnar <mingo@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>
Cc: Dan Williams <dan.j.williams@xxxxxxxxx>
Cc: Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx>
Cc: Davidlohr Bueso <dave@xxxxxxxxxxxx>
Cc: Nikolay Aleksandrov <nikolay@xxxxxxxxxxxxxxxxxxx>
Cc: "David S. Miller" <davem@xxxxxxxxxxxxx>
Cc: "Peter Zijlstra (Intel)" <peterz@xxxxxxxxxxxxx>
Cc: Rasmus Villemoes <linux@xxxxxxxxxxxxxxxxxx>
Cc: Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
Cc: Dmitry Vyukov <dvyukov@xxxxxxxxxx>
Cc: Alexander Potapenko <glider@xxxxxxxxxx>
Cc: linux-kernel@xxxxxxxxxxxxxxx
Cc: linux-media@xxxxxxxxxxxxxxx
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: linaro-mm-sig@xxxxxxxxxxxxxxxx
---
include/linux/kfence.h | 4 ++++
kernel/async.c | 63 ++++++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 65 insertions(+), 2 deletions(-)
diff --git a/include/linux/kfence.h b/include/linux/kfence.h
index 82096bfafaa1..d71f30c626ae 100644
--- a/include/linux/kfence.h
+++ b/include/linux/kfence.h
@@ -15,6 +15,7 @@
#include <linux/wait.h>
struct completion;
+struct fence;
struct kfence {
wait_queue_head_t wait;
@@ -29,6 +30,9 @@ extern int kfence_add(struct kfence *fence, struct kfence *after, gfp_t gfp);
extern int kfence_add_completion(struct kfence *fence,
struct completion *x,
gfp_t gfp);
+extern int kfence_add_dma(struct kfence *fence,
+ struct fence *dma,
+ gfp_t gfp);
extern void kfence_pending(struct kfence *fence);
extern void kfence_signal(struct kfence *fence);
extern void kfence_wait(struct kfence *fence);
diff --git a/kernel/async.c b/kernel/async.c
index db22b890711e..01552d23a916 100644
--- a/kernel/async.c
+++ b/kernel/async.c
@@ -50,6 +50,7 @@ asynchronous and synchronous parts of the kernel.
#include <linux/async.h>
#include <linux/atomic.h>
+#include <linux/fence.h>
#include <linux/kfence.h>
#include <linux/ktime.h>
#include <linux/export.h>
@@ -122,9 +123,10 @@ static atomic_t entry_count;
* allowing multiple pending / signals to be sent before the kfence is
* complete.
*
- * kfence_add() / kfence_add_completion()
+ * kfence_add() / kfence_add_completion() / kfence_add_dma()
*
- * sets the kfence to wait upon another fence, or completion respectively.
+ * sets the kfence to wait upon another fence, completion, or DMA fence
+ * respectively.
*
* Unlike completions, kfences are expected to live inside more complex graphs
* and form the basis for parallel execution of interdependent and so are
@@ -484,6 +486,63 @@ int kfence_add_completion(struct kfence *fence, struct completion *x, gfp_t gfp)
}
EXPORT_SYMBOL_GPL(kfence_add_completion);
+struct dma_fence_cb {
+ struct fence_cb base;
+ struct kfence *fence;
+};
+
+static void dma_kfence_wake(struct fence *dma, struct fence_cb *data)
+{
+ struct dma_fence_cb *cb = container_of(data, typeof(*cb), base);
+ kfence_signal(cb->fence);
+ kfence_put(cb->fence);
+ kfree(cb);
+}
+
+/**
+ * kfence_add_dma - set the fence to wait upon a DMA fence
+ * @fence: this kfence
+ * @dma: target DMA fence to wait upon
+ * @gfp: the allowed allocation type
+ *
+ * kfence_add_dma() causes the @fence to wait upon completion of a DMA fence.
+ *
+ * Returns 1 if the @fence was successfully to the waitqueue of @dma, 0
+ * if @dma was already signaled (and so not added), or a negative error code.
+ */
+int kfence_add_dma(struct kfence *fence, struct fence *dma, gfp_t gfp)
+{
+ struct dma_fence_cb *cb;
+ int ret;
+
+ if (!dma || fence_is_signaled(dma))
+ return 0;
+
+ cb = kmalloc(sizeof(*cb), gfp);
+ if (!cb) {
+ if (!gfpflags_allow_blocking(gfp))
+ return -ENOMEM;
+
+ return fence_wait(dma, false);
+ }
+
+ cb->fence = kfence_get(fence);
+ kfence_pending(fence);
+
+ ret = fence_add_callback(dma, &cb->base, dma_kfence_wake);
+ if (ret == 0) {
+ /* signal fence add and is pending */
+ ret = 1;
+ } else {
+ dma_kfence_wake(dma, &cb->base);
+ if (ret == -ENOENT) /* fence already signaled */
+ ret = 0;
+ }
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(kfence_add_dma);
+
static async_cookie_t lowest_in_progress(struct async_domain *domain)
{
struct list_head *pending;
--
2.8.1
--
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