From: Lyude Paul <lyude@redhat.com>
To: stable@vger.kernel.org
Cc: "Christian König" <christian.koenig@amd.com>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org,
linaro-mm-sig@lists.linaro.org, linux-kernel@vger.kernel.org
Subject: [PATCH 2/4] dma-buf: make reservation_object_copy_fences rcu save
Date: Thu, 30 Nov 2017 19:23:04 -0500 [thread overview]
Message-ID: <20171201002311.28098-3-lyude@redhat.com> (raw)
In-Reply-To: <20171201002311.28098-1-lyude@redhat.com>
From: Christian König <christian.koenig@amd.com>
Stop requiring that the src reservation object is locked for this operation.
commit 39e16ba16c147e662bf9fbcee9a99d70d420382f upstream
Acked-by: Chunming Zhou <david1.zhou@amd.com>
Signed-off-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/1504551766-5093-1-git-send-email-deathsimple@vodafone.de
Signed-off-by: Lyude Paul <lyude@redhat.com>
---
drivers/dma-buf/reservation.c | 56 ++++++++++++++++++++++++++++++++-----------
1 file changed, 42 insertions(+), 14 deletions(-)
diff --git a/drivers/dma-buf/reservation.c b/drivers/dma-buf/reservation.c
index dec3a815455d..b44d9d7db347 100644
--- a/drivers/dma-buf/reservation.c
+++ b/drivers/dma-buf/reservation.c
@@ -266,8 +266,7 @@ EXPORT_SYMBOL(reservation_object_add_excl_fence);
* @dst: the destination reservation object
* @src: the source reservation object
*
-* Copy all fences from src to dst. Both src->lock as well as dst-lock must be
-* held.
+* Copy all fences from src to dst. dst-lock must be held.
*/
int reservation_object_copy_fences(struct reservation_object *dst,
struct reservation_object *src)
@@ -277,33 +276,62 @@ int reservation_object_copy_fences(struct reservation_object *dst,
size_t size;
unsigned i;
- src_list = reservation_object_get_list(src);
+ rcu_read_lock();
+ src_list = rcu_dereference(src->fence);
+retry:
if (src_list) {
- size = offsetof(typeof(*src_list),
- shared[src_list->shared_count]);
+ unsigned shared_count = src_list->shared_count;
+
+ size = offsetof(typeof(*src_list), shared[shared_count]);
+ rcu_read_unlock();
+
dst_list = kmalloc(size, GFP_KERNEL);
if (!dst_list)
return -ENOMEM;
- dst_list->shared_count = src_list->shared_count;
- dst_list->shared_max = src_list->shared_count;
- for (i = 0; i < src_list->shared_count; ++i)
- dst_list->shared[i] =
- dma_fence_get(src_list->shared[i]);
+ rcu_read_lock();
+ src_list = rcu_dereference(src->fence);
+ if (!src_list || src_list->shared_count > shared_count) {
+ kfree(dst_list);
+ goto retry;
+ }
+
+ dst_list->shared_count = 0;
+ dst_list->shared_max = shared_count;
+ for (i = 0; i < src_list->shared_count; ++i) {
+ struct dma_fence *fence;
+
+ fence = rcu_dereference(src_list->shared[i]);
+ if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
+ &fence->flags))
+ continue;
+
+ if (!dma_fence_get_rcu(fence)) {
+ kfree(dst_list);
+ src_list = rcu_dereference(src->fence);
+ goto retry;
+ }
+
+ if (dma_fence_is_signaled(fence)) {
+ dma_fence_put(fence);
+ continue;
+ }
+
+ dst_list->shared[dst_list->shared_count++] = fence;
+ }
} else {
dst_list = NULL;
}
+ new = dma_fence_get_rcu_safe(&src->fence_excl);
+ rcu_read_unlock();
+
kfree(dst->staged);
dst->staged = NULL;
src_list = reservation_object_get_list(dst);
-
old = reservation_object_get_excl(dst);
- new = reservation_object_get_excl(src);
-
- dma_fence_get(new);
preempt_disable();
write_seqcount_begin(&dst->seq);
--
2.14.3
next prev parent reply other threads:[~2017-12-01 0:24 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-12-01 0:23 [PATCH 0/4] Backported amdgpu ttm deadlock fixes for 4.14 Lyude Paul
2017-12-01 0:23 ` Lyude Paul [this message]
2017-12-01 8:27 ` Christian König
2017-12-04 11:45 ` Greg KH
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