On Wed, Jul 21, 2021 at 11:21:33AM +0200, Christian König wrote:
That the caller doesn't need to keep a reference is rather risky and not defensive at all.
Especially dma_buf_poll got that horrible wrong, so better remove that sentence and also clarify that the callback might be called in atomic or interrupt context.
Signed-off-by: Christian König christian.koenig@amd.com
I'm very vary of aspirational interface docs for cross-anything, it just means everyone does whatever they feel like. I think I get what you aim for here, but this needs more careful wording.
drivers/dma-buf/dma-fence.c | 13 +++++-------- 1 file changed, 5 insertions(+), 8 deletions(-)
diff --git a/drivers/dma-buf/dma-fence.c b/drivers/dma-buf/dma-fence.c index ce0f5eff575d..1e82ecd443fa 100644 --- a/drivers/dma-buf/dma-fence.c +++ b/drivers/dma-buf/dma-fence.c @@ -616,20 +616,17 @@ EXPORT_SYMBOL(dma_fence_enable_sw_signaling);
- @cb: the callback to register
- @func: the function to call
- Add a software callback to the fence. The caller should keep a reference to
- the fence.
Instead of your "The caller should" what about:
It is not required to hold rerence to @fence. But since the fence can disappear as soon as @cb has returned callers generally must hold their own reference to prevent issues.
With that or something similar that explains when we must do what and not vague "should" wording.
Reviewed-by: Daniel Vetter daniel.vetter@ffwll.ch
- @cb will be initialized by dma_fence_add_callback(), no initialization
- by the caller is required. Any number of callbacks can be registered
- to a fence, but a callback can only be registered to one fence at a time.
- Note that the callback can be called from an atomic context. If
- fence is already signaled, this function will return -ENOENT (and
- If fence is already signaled, this function will return -ENOENT (and
- *not* call the callback).
- Add a software callback to the fence. Same restrictions apply to
- refcount as it does to dma_fence_wait(), however the caller doesn't need to
- keep a refcount to fence afterward dma_fence_add_callback() has returned:
- when software access is enabled, the creator of the fence is required to keep
- the fence alive until after it signals with dma_fence_signal(). The callback
- itself can be called from irq context.
- Note that the callback can be called from an atomic context or irq context.
- Returns 0 in case of success, -ENOENT if the fence is already signaled
- and -EINVAL in case of error.
-- 2.25.1