Signed-off-by: Christian König <ckoe...@able.fritz.box>
---
drivers/dma-buf/dma-fence.c | 59 +++++++++++++++++++++++++++----------
include/linux/dma-fence.h | 9 ++++--
2 files changed, 51 insertions(+), 17 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c
index 3f78c56b58dc..2bce620eacac 100644
--- a/drivers/dma-buf/dma-fence.c
+++ b/drivers/dma-buf/dma-fence.c
@@ -345,33 +345,23 @@ void __dma_fence_might_wait(void)
}
#endif
-
/**
- * dma_fence_signal_timestamp_locked - signal completion of a fence
+ * dma_fence_signal_internal - internal signal completion of a fence
* @fence: the fence to signal
* @timestamp: fence signal timestamp in kernel's CLOCK_MONOTONIC time domain
*
- * Signal completion for software callbacks on a fence, this will unblock
- * dma_fence_wait() calls and run all the callbacks added with
- * dma_fence_add_callback(). Can be called multiple times, but since a fence
- * can only go from the unsignaled to the signaled state and not back, it will
- * only be effective the first time. Set the timestamp provided as the fence
- * signal timestamp.
- *
- * Unlike dma_fence_signal_timestamp(), this function must be called with
- * &dma_fence.lock held.
+ * Internal signal the dma_fence without error checking. Should *NEVER* be used
+ * by drivers or external code directly.
*
* Returns 0 on success and a negative error value when @fence has been
* signalled already.
*/
-int dma_fence_signal_timestamp_locked(struct dma_fence *fence,
- ktime_t timestamp)
+int dma_fence_signal_internal(struct dma_fence *fence, ktime_t timestamp)
{
struct dma_fence_cb *cur, *tmp;
struct list_head cb_list;
lockdep_assert_held(fence->lock);
-
if (unlikely(test_and_set_bit(DMA_FENCE_FLAG_SIGNALED_BIT,
&fence->flags)))
return -EINVAL;
@@ -390,7 +380,46 @@ int dma_fence_signal_timestamp_locked(struct dma_fence
*fence,
return 0;
}
-EXPORT_SYMBOL(dma_fence_signal_timestamp_locked);
+EXPORT_SYMBOL(dma_fence_signal_internal);
+
+/**
+ * dma_fence_signal_timestamp_locked - signal completion of a fence
+ * @fence: the fence to signal
+ * @timestamp: fence signal timestamp in kernel's CLOCK_MONOTONIC time domain
+ *
+ * Signal completion for software callbacks on a fence, this will unblock
+ * dma_fence_wait() calls and run all the callbacks added with
+ * dma_fence_add_callback(). Can be called multiple times, but since a fence
+ * can only go from the unsignaled to the signaled state and not back, it will
+ * only be effective the first time. Set the timestamp provided as the fence
+ * signal timestamp.
+ *
+ * Unlike dma_fence_signal_timestamp(), this function must be called with
+ * &dma_fence.lock held.
+ *
+ * Returns 0 on success and a negative error value when @fence has been
+ * signalled already.
+ */
+int dma_fence_signal_timestamp_locked(struct dma_fence *fence,
+ ktime_t timestamp)
+{
+ /*
+ * We have the re-occurring problem that people try to invent a
+ * DMA-fences implementation which signals fences based on an userspace
+ * IOCTL.
+ *
+ * This is well known as source of hard to track down crashes and is
+ * documented to be an invalid approach. The problem is that it seems
+ * to work during initial testing and only long term tests points out
+ * why this can never work correctly.
+ *
+ * So give at least a warning when people try to signal a fence from
+ * task context and not from interrupts or a work item. This check is
+ * certainly not perfect but better than nothing.
+ */
+ WARN_ON_ONCE(!in_interrupt() && !current_work());
+ return dma_fence_signal_internal(fence, timestamp);
+}
/**
* dma_fence_signal_timestamp - signal completion of a fence
diff --git a/include/linux/dma-fence.h b/include/linux/dma-fence.h
index 64639e104110..8dbcd66989b8 100644
--- a/include/linux/dma-fence.h
+++ b/include/linux/dma-fence.h
@@ -369,6 +369,7 @@ int dma_fence_signal_locked(struct dma_fence *fence);
int dma_fence_signal_timestamp(struct dma_fence *fence, ktime_t timestamp);
int dma_fence_signal_timestamp_locked(struct dma_fence *fence,
ktime_t timestamp);
+int dma_fence_signal_internal(struct dma_fence *fence, ktime_t timestamp);
signed long dma_fence_default_wait(struct dma_fence *fence,
bool intr, signed long timeout);
int dma_fence_add_callback(struct dma_fence *fence,
@@ -422,7 +423,7 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
return true;
if (fence->ops->signaled && fence->ops->signaled(fence)) {
- dma_fence_signal_locked(fence);
+ dma_fence_signal_internal(fence, ktime_get());
return true;
}
@@ -448,11 +449,15 @@ dma_fence_is_signaled_locked(struct dma_fence *fence)
static inline bool
dma_fence_is_signaled(struct dma_fence *fence)
{
+ unsigned long flags;
+
if (test_bit(DMA_FENCE_FLAG_SIGNALED_BIT, &fence->flags))
return true;
if (fence->ops->signaled && fence->ops->signaled(fence)) {
- dma_fence_signal(fence);
+ spin_lock_irqsave(fence->lock, flags);
+ dma_fence_signal_internal(fence, ktime_get());
+ spin_unlock_irqrestore(fence->lock, flags);
return true;
}
