Re: [PATCH 2/9] block-copy: add missing coroutine_fn annotations

[Kevin Wolf]

Am 03.11.2022 um 17:56 hat Paolo Bonzini geschrieben:
> On 11/3/22 14:41, Emanuele Giuseppe Esposito wrote:
> > block_copy_reset_unallocated and block_copy_is_cluster_allocated are
> > only called by backup_run, a corotuine_fn itself.

s/corotuine_fn/coroutine_fn/

> > 
> > Same applies to block_copy_block_status, called by
> > block_copy_dirty_clusters.
> > 
> > Therefore mark them as coroutine too.
> > 
> > Signed-off-by: Emanuele Giuseppe Esposito <eesposit@redhat.com>
> 
> They don't need to be coroutine_fn.  coroutine_fn is needed if you call
> another coroutine_fn, but not if you _are only called_ by coroutine_fn.
> There is nothing in these functions that needs them to be called from a
> coroutine.
> 
> The only exception is qemu_coroutine_yield(), which is the only leaf
> coroutine_fn.

I think it can make sense to have coroutine_fn as a documentation for
things that are only ever called in a coroutine even if they could
theoretically also work outside of coroutine context.

Otherwise, when we want to introduce a coroutine_fn call somewhere, it's
not only less obvious that it's even possible to do, but we'll have to
add potentially many additional coroutine_fn annotations in the whole
call chain in an otherwise unrelated patch.

Kevin