[PATCH v2 3/7] kfence: Extend kfences for listening on DMA fences

[Chris Wilson]

dma-buf provides an interfaces for receiving notifications from DMA
hardware, and for implicitly tracking fences used for rendering into
dma-buf. We want to be able to use these event sources along with kfence
for easy collection and combining with other events.

Signed-off-by: Chris Wilson 
Cc: Sumit Semwal 
Cc: Shuah Khan 
Cc: Tejun Heo 
Cc: Daniel Vetter 
Cc: Andrew Morton 
Cc: Ingo Molnar 
Cc: Kees Cook 
Cc: Thomas Gleixner 
Cc: "Paul E. McKenney" 
Cc: Dan Williams 
Cc: Andrey Ryabinin 
Cc: Davidlohr Bueso 
Cc: Nikolay Aleksandrov 
Cc: "David S. Miller" 
Cc: "Peter Zijlstra (Intel)" 
Cc: Rasmus Villemoes 
Cc: Andy Shevchenko 
Cc: Dmitry Vyukov 
Cc: Alexander Potapenko 
Cc: linux-kernel@vger.kernel.org
Cc: linux-me...@vger.kernel.org
Cc: dri-de...@lists.freedesktop.org
Cc: linaro-mm-...@lists.linaro.org
---
 drivers/dma-buf/fence.c   | 58 +++
 drivers/dma-buf/reservation.c | 48 +++
 include/linux/fence.h |  6 +
 include/linux/kfence.h|  2 ++
 include/linux/reservation.h   |  7 ++
 kernel/kfence.c   |  8 ++
 6 files changed, 129 insertions(+)

diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c
index 7b05dbe9b296..3f06b3b1b4cc 100644
--- a/drivers/dma-buf/fence.c
+++ b/drivers/dma-buf/fence.c
@@ -22,6 +22,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #define CREATE_TRACE_POINTS
 #include 
@@ -530,3 +531,60 @@ fence_init(struct fence *fence, const struct fence_ops 
*ops,
trace_fence_init(fence);
 }
 EXPORT_SYMBOL(fence_init);
+
+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_complete(cb->fence);
+   kfence_put(cb->fence);
+   kfree(cb);
+}
+
+/**
+ * kfence_await_dma_fence - 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_await_dma_fence(struct kfence *fence, struct fence *dma, gfp_t gfp)
+{
+   struct dma_fence_cb *cb;
+   int ret;
+
+   if (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_await(fence);
+
+   ret = fence_add_callback(dma, >base, dma_kfence_wake);
+   if (ret == 0) {
+   ret = 1;
+   } else {
+   dma_kfence_wake(dma, >base);
+   if (ret == -ENOENT) /* fence already signaled */
+   ret = 0;
+   }
+
+   return ret;
+}
+EXPORT_SYMBOL_GPL(kfence_await_dma_fence);
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 9566a62ad8e3..138b792af0c3 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -543,3 +543,51 @@ unlock_retry:
goto retry;
 }
 EXPORT_SYMBOL_GPL(reservation_object_test_signaled_rcu);
+
+/**
+ * kfence_add_reservation - set the fence to wait upon a reservation_object
+ * @fence: this kfence
+ * @resv: target reservation_object (collection of DMA fences) to wait upon
+ * @write: Wait for read or read/write access
+ * @gfp: the allowed allocation type
+ *
+ * kfence_add_reservation() causes the @fence to wait upon completion of the
+ * reservation object (a collection of DMA fences), either for read access
+ * or for read/write access.
+ *
+ * Returns 1 if the @fence was successfully to the waitqueues of @resv, 0
+ * if @resev was already signaled (and so not added), or a negative error code.
+ */
+int kfence_await_reservation(struct kfence *fence,
+struct reservation_object *resv,
+bool write,
+gfp_t gfp)
+{
+   struct fence *excl, **shared;
+   unsigned int count, i;
+   int ret;
+
+   ret = reservation_object_get_fences_rcu(resv, , , );
+   if (ret)
+   return ret;
+
+   if (write) {
+ 

[PATCH v2 3/7] kfence: Extend kfences for listening on DMA fences

[Chris Wilson]

dma-buf provides an interfaces for receiving notifications from DMA
hardware, and for implicitly tracking fences used for rendering into
dma-buf. We want to be able to use these event sources along with kfence
for easy collection and combining with other events.

Signed-off-by: Chris Wilson 
Cc: Sumit Semwal 
Cc: Shuah Khan 
Cc: Tejun Heo 
Cc: Daniel Vetter 
Cc: Andrew Morton 
Cc: Ingo Molnar 
Cc: Kees Cook 
Cc: Thomas Gleixner 
Cc: "Paul E. McKenney" 
Cc: Dan Williams 
Cc: Andrey Ryabinin 
Cc: Davidlohr Bueso 
Cc: Nikolay Aleksandrov 
Cc: "David S. Miller" 
Cc: "Peter Zijlstra (Intel)" 
Cc: Rasmus Villemoes 
Cc: Andy Shevchenko 
Cc: Dmitry Vyukov 
Cc: Alexander Potapenko 
Cc: linux-kernel@vger.kernel.org
Cc: linux-me...@vger.kernel.org
Cc: dri-de...@lists.freedesktop.org
Cc: linaro-mm-...@lists.linaro.org
---
 drivers/dma-buf/fence.c   | 58 +++
 drivers/dma-buf/reservation.c | 48 +++
 include/linux/fence.h |  6 +
 include/linux/kfence.h|  2 ++
 include/linux/reservation.h   |  7 ++
 kernel/kfence.c   |  8 ++
 6 files changed, 129 insertions(+)

diff --git a/drivers/dma-buf/fence.c b/drivers/dma-buf/fence.c
index 7b05dbe9b296..3f06b3b1b4cc 100644
--- a/drivers/dma-buf/fence.c
+++ b/drivers/dma-buf/fence.c
@@ -22,6 +22,7 @@
 #include 
 #include 
 #include 
+#include 
 
 #define CREATE_TRACE_POINTS
 #include 
@@ -530,3 +531,60 @@ fence_init(struct fence *fence, const struct fence_ops 
*ops,
trace_fence_init(fence);
 }
 EXPORT_SYMBOL(fence_init);
+
+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_complete(cb->fence);
+   kfence_put(cb->fence);
+   kfree(cb);
+}
+
+/**
+ * kfence_await_dma_fence - 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_await_dma_fence(struct kfence *fence, struct fence *dma, gfp_t gfp)
+{
+   struct dma_fence_cb *cb;
+   int ret;
+
+   if (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_await(fence);
+
+   ret = fence_add_callback(dma, >base, dma_kfence_wake);
+   if (ret == 0) {
+   ret = 1;
+   } else {
+   dma_kfence_wake(dma, >base);
+   if (ret == -ENOENT) /* fence already signaled */
+   ret = 0;
+   }
+
+   return ret;
+}
+EXPORT_SYMBOL_GPL(kfence_await_dma_fence);
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index 9566a62ad8e3..138b792af0c3 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -543,3 +543,51 @@ unlock_retry:
goto retry;
 }
 EXPORT_SYMBOL_GPL(reservation_object_test_signaled_rcu);
+
+/**
+ * kfence_add_reservation - set the fence to wait upon a reservation_object
+ * @fence: this kfence
+ * @resv: target reservation_object (collection of DMA fences) to wait upon
+ * @write: Wait for read or read/write access
+ * @gfp: the allowed allocation type
+ *
+ * kfence_add_reservation() causes the @fence to wait upon completion of the
+ * reservation object (a collection of DMA fences), either for read access
+ * or for read/write access.
+ *
+ * Returns 1 if the @fence was successfully to the waitqueues of @resv, 0
+ * if @resev was already signaled (and so not added), or a negative error code.
+ */
+int kfence_await_reservation(struct kfence *fence,
+struct reservation_object *resv,
+bool write,
+gfp_t gfp)
+{
+   struct fence *excl, **shared;
+   unsigned int count, i;
+   int ret;
+
+   ret = reservation_object_get_fences_rcu(resv, , , );
+   if (ret)
+   return ret;
+
+   if (write) {
+   for (i = 0; i < count; i++) {
+   ret |= kfence_await_dma_fence(fence, shared[i], gfp);
+   if (ret < 0)
+   goto out;
+   }
+   }
+
+   if (excl)
+   ret |= kfence_await_dma_fence(fence, excl, gfp);
+
+out:
+   fence_put(excl);
+   for (i = 0; i < count; i++)
+   fence_put(shared[i]);
+   kfree(shared);
+
+   return ret;
+}