Re: [RFC PATCH] char-fe: implement qemu_chr_fe_backend_name

On 10/8/26 17:35, Alex Bennée wrote:
> A number of chardev users where calling qemu_chr_fe_get_driver() which
> is discouraged as it blocks backend hotswap. As the pattern is common
> and need for the string is transitory add a helper and keep
> qemu_chr_fe_get_driver() for those that really need the funkiness of
> poking around the backend setup.
> 
> Signed-off-by: Alex Bennée <[email protected]>
> Suggested-by: Peter Maydell <[email protected]>
> ---
>   include/chardev/char-fe.h       | 13 ++++++++++++-
>   backends/cryptodev-vhost-user.c |  8 +-------
>   backends/rng-egd.c              |  8 +-------
>   backends/vhost-user.c           |  8 +-------
>   hw/char/imx_serial.c            |  4 ++--
>   5 files changed, 17 insertions(+), 24 deletions(-)
> 
> diff --git a/include/chardev/char-fe.h b/include/chardev/char-fe.h
> index 5f8a6df17dc..13218d04c8d 100644
> --- a/include/chardev/char-fe.h
> +++ b/include/chardev/char-fe.h
> @@ -52,7 +52,8 @@ void qemu_chr_fe_deinit(CharFrontend *c, bool del);
>    * associated Chardev.
>    * Note: avoid this function as the driver should never be accessed directly,
>    *       especially by the frontends that support chardevice hotswap.
> - *       Consider qemu_chr_fe_backend_connected() to check for driver existence
> + *       Consider qemu_chr_fe_backend_connected() to check for driver
> + *       existence or qemu_chr_fe_backend_name() if you need the name.
>    */
>   Chardev *qemu_chr_fe_get_driver(CharFrontend *c);
>   
> @@ -70,6 +71,16 @@ bool qemu_chr_fe_backend_connected(CharFrontend *c);
>    */
>   bool qemu_chr_fe_backend_open(CharFrontend *c);
>   
> +/**
> +  * qemu_chr_fe_backend_name:
> +  *
> +  * Returns: caller freeable string or NULL
> +  */
> +static inline char * qemu_chr_fe_backend_name(CharFrontend *c)
> +{
> +    return (c->chr && c->chr->label) ? g_strdup(c->chr->label) : NULL;
> +}

This looks like a safe setter for the "chardev" ObjectProperty.
Maybe we could go one step further and unify adding a
object_class_property_add_chardev() helper?