[PATCH v7 03/11] server: Ensure async completion callback is called on synchronous failure.

[Zebediah Figura]

On 3/19/22 17:28, Jinoh Kang wrote:
> async_set_result() is the only way the async completion callback can be
> called.  If the async were a request async and the I/O failed even
> before it was marked as pending, async_handoff() simply discards the
> async without either calling async_set_result() or directly invoking the
> completion callback.  This leads to memory leak.
> 
> Fix this by calling the completion_callback on synchronous failure path
> if it was not already called, setting it to NULL afterwards.
> 
> Signed-off-by: Jinoh Kang <jinoh.kang.kr at gmail.com>
> ---

I'm going to nitpick this, because I think clarity is very important here.

The assumption that's currently made about completion callbacks is that 
they're only set if the async is actually queued, and that assumption 
holds for all of the places that currently use them.

That could be reasonably changed, I think (although I'm not sure it 
strictly needs to be—we could duplicate clearing events, I think either 
approach is reasonable) but it does mean that this description isn't 
really accurate.