linux-kernel - Re: [PATCH 1/3] mailbox: Add ability for clients to abort data in channel

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Date:   Wed, 16 Jan 2019 10:22:38 -0600
From:   Jassi Brar <jassisinghbrar@...il.com>
To:     CK Hu <ck.hu@...iatek.com>
Cc:     Matthias Brugger <matthias.bgg@...il.com>,
        Houlong Wei <houlong.wei@...iatek.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org, srv_heupstream@...iatek.com
Subject: Re: [PATCH 1/3] mailbox: Add ability for clients to abort data in channel

On Tue, Jan 15, 2019 at 11:07 PM CK Hu <ck.hu@...iatek.com> wrote:
>
> This patch supplies a new framework API, mbox_abort_channel(), and
> a new controller interface, abort_data().
>
> For some client's application, it need to clean up the data in channel
> but keep the channel so it could send data to channel later.
>
> Signed-off-by: CK Hu <ck.hu@...iatek.com>
> ---
>  drivers/mailbox/mailbox.c          | 23 +++++++++++++++++++++++
>  include/linux/mailbox_client.h     |  1 +
>  include/linux/mailbox_controller.h |  4 ++++
>  3 files changed, 28 insertions(+)
>
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> index c6a7d4582dc6..281647162c76 100644
> --- a/drivers/mailbox/mailbox.c
> +++ b/drivers/mailbox/mailbox.c
> @@ -428,6 +428,29 @@ struct mbox_chan *mbox_request_channel_byname(struct mbox_client *cl,
>  }
>  EXPORT_SYMBOL_GPL(mbox_request_channel_byname);
>
> +/**
> + * mbox_abort_channel - The client abort all data in a mailbox
> + *                     channel by this call.
> + * @chan: The mailbox channel to be aborted.
> + */
> +void mbox_abort_channel(struct mbox_chan *chan)
> +{
> +       unsigned long flags;
> +
> +       if (!chan || !chan->cl)
> +               return;
> +
> +       if (chan->mbox->ops->abort_data)
> +               chan->mbox->ops->abort_data(chan);
> +
> +       /* The queued TX requests are simply aborted, no callbacks are made */
> +       spin_lock_irqsave(&chan->lock, flags);
> +       chan->cl = NULL;
> +       chan->active_req = NULL;
> +       spin_unlock_irqrestore(&chan->lock, flags);
> +}
>
Why not just release and then request channel again ?
mbox_abort_channel() is just a copy of mbox_free_channel() and if the
abort can sleep, that is more reason to just do that.