Re: [PATCH V5 03/13] iothread: tracking iothread users with holder name

[Stefan Hajnoczi <stefanha@redhat.com>]

[-- Attachment #1: Type: text/plain, Size: 2398 bytes --]

On Thu, Mar 05, 2026 at 10:24:49PM +0800, Zhang Chen wrote:
> Introduce iothread_get_aio_context() with a 'holder' argument and its
> counterpart iothread_put_aio_context().
> 
> Previously, users of an IOThread's AioContext did not explicitly
> record their identity, making it difficult to debug which devices or
> subsystems were pinning an IOThread.
> 
> This patch enhances the reference counting mechanism by:
> 1. Automatically incrementing the object reference count when a context
>    is retrieved.
> 2. Tracking holders by name using iothread_ref() and iothread_unref().
> 
> In iothread_instance_finalize(), we now retrieve the source name from
> the GMainContext to correctly unref the initial internal holder.
> 
> Signed-off-by: Zhang Chen <zhangckid@gmail.com>
> ---
>  include/system/iothread.h |  3 ++-
>  iothread.c                | 28 ++++++++++++++++++++++++++--
>  2 files changed, 28 insertions(+), 3 deletions(-)
> 
> diff --git a/include/system/iothread.h b/include/system/iothread.h
> index 21a76bd70d..595abeefbe 100644
> --- a/include/system/iothread.h
> +++ b/include/system/iothread.h
> @@ -47,7 +47,8 @@ DECLARE_INSTANCE_CHECKER(IOThread, IOTHREAD,
>  
>  char *iothread_get_id(IOThread *iothread);
>  IOThread *iothread_by_id(const char *id);
> -AioContext *iothread_get_aio_context(IOThread *iothread);
> +AioContext *iothread_get_aio_context(IOThread *iothread, const char *holder);

This commit breaks all iothread_get_aio_context() callers because they
are not yet converted. The build will fail here.

Every commit must build and pass the tests. This is necessary so that
git-bisect(1) works and it also makes backporting patches much easier
when there are no implicit dependencies between commits.

Please structure this patch series in a way that keeps the build and
tests passing. One way to do this is to give the new API a different
name like:

  AioContext *iothread_get_aio_context(IOThread *iothread);
+ AioContext *iothread_ref_and_get_aio_context(IOThread *iothread, const char *holder);

That name also makes clear that a reference will be taken on the
IOThread. You could then require callers to call iothread_unref()
directly instead of iothread_put_aio_context().

One of the last commits in the patch series could remove the old
iothread_get_aio_context() after everything has been converted.

[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 488 bytes --]