linux-kernel - Re: [PATCH] kdbus: Make kdbus_bus

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Message-ID: <CANq1E4SnYpxUJ3dDyCCYh=mXtE8kW8g_20xsUX-0W+CgNhNutg@mail.gmail.com>
Date:	Wed, 22 Apr 2015 14:01:05 +0200
From:	David Herrmann <dh.herrmann@...il.com>
To:	Tobias Klauser <tklauser@...tanz.ch>
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Daniel Mack <daniel@...que.org>,
	David Herrmann <dh.herrmann@...glemail.com>,
	Djalal Harouni <tixxdz@...ndz.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] kdbus: Make kdbus_bus_unref() return void

Hi

On Wed, Apr 22, 2015 at 1:50 PM, Tobias Klauser <tklauser@...tanz.ch> wrote:
> kdbus_bus_unref() always returns NULL and none of its callers use the
> return value, so make it return void.
>
> Signed-off-by: Tobias Klauser <tklauser@...tanz.ch>

All our destructors return NULL, which allows simple assignment during
destruction:
  foo->bus = kdbus_bus_unref(foo->bus);
And our destructors ignore NULL, so no reason to conditionalize the
call to unref(). This simplifies our error-paths a lot, and I'd like
to keep it that way.

I'd prefer to stay uniform across our code-base and keep returning
NULL. It's neither a fast-path, nor do return values require any
memory writes (usually register passing, iirc).

Thanks
David

> ---
>  ipc/kdbus/bus.c | 5 +----
>  ipc/kdbus/bus.h | 2 +-
>  2 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/ipc/kdbus/bus.c b/ipc/kdbus/bus.c
> index 9d0679e..dce7b08 100644
> --- a/ipc/kdbus/bus.c
> +++ b/ipc/kdbus/bus.c
> @@ -202,14 +202,11 @@ struct kdbus_bus *kdbus_bus_ref(struct kdbus_bus *bus)
>   *
>   * Release a reference. If the reference count drops to 0, the bus will be
>   * freed.
> - *
> - * Return: NULL
>   */
> -struct kdbus_bus *kdbus_bus_unref(struct kdbus_bus *bus)
> +void kdbus_bus_unref(struct kdbus_bus *bus)
>  {
>         if (bus)
>                 kdbus_node_unref(&bus->node);
> -       return NULL;
>  }
>
>  /**
> diff --git a/ipc/kdbus/bus.h b/ipc/kdbus/bus.h
> index 5bea5ef..266af60 100644
> --- a/ipc/kdbus/bus.h
> +++ b/ipc/kdbus/bus.h
> @@ -84,7 +84,7 @@ struct kdbus_bus {
>  };
>
>  struct kdbus_bus *kdbus_bus_ref(struct kdbus_bus *bus);
> -struct kdbus_bus *kdbus_bus_unref(struct kdbus_bus *bus);
> +void kdbus_bus_unref(struct kdbus_bus *bus);
>
>  struct kdbus_conn *kdbus_bus_find_conn_by_id(struct kdbus_bus *bus, u64 id);
>  void kdbus_bus_broadcast(struct kdbus_bus *bus,
> --
> 2.2.2
>
>
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