Re: [PATCH 3/3] coroutine-lock: qemu_co_queue_restart_all is a coroutine-only qemu_co_enter_all

[Eric Blake <eblake@redhat.com>]

On Wed, Apr 27, 2022 at 03:08:30PM +0200, Paolo Bonzini wrote:
> qemu_co_queue_restart_all is basically the same as qemu_co_enter_all
> but without a QemuLockable argument.  That's perfectly fine, but only as
> long as the function is marked coroutine_fn.  If used outside coroutine
> context, qemu_co_queue_wait will attempt to take the lock and that
> is just broken: if you are calling qemu_co_queue_restart_all outside
> coroutine context, the lock is going to be a QemuMutex which cannot be
> taken twice by the same thread.
> 
> The patch adds the marker to qemu_co_queue_restart_all and to its sole
> non-coroutine_fn caller; it then reimplements the function in terms of
> qemu_co_enter_all_impl, to remove duplicated code and to clarify that the
> latter also works in coroutine context.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
> ---
>  block/io.c                 |  2 +-
>  include/qemu/coroutine.h   |  7 ++++---
>  util/qemu-coroutine-lock.c | 21 ++++++---------------
>  3 files changed, 11 insertions(+), 19 deletions(-)
>

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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