linux-kernel - Re: [PATCH v2 01/19] mailbox: Add device-managed registration functions

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Date:   Tue, 18 Dec 2018 16:04:45 +0000
From:   Sudeep Holla <sudeep.holla@....com>
To:     Thierry Reding <thierry.reding@...il.com>
Cc:     Jassi Brar <jassisinghbrar@...il.com>,
        linux-kernel@...r.kernel.org, Andy Gospodarek <gospo@...adcom.com>,
        Anup Patel <anup.patel@...adcom.com>,
        Bjorn Andersson <bjorn.andersson@...aro.org>,
        Caesar Wang <wxt@...k-chips.com>, CK Hu <ck.hu@...iatek.com>,
        Dong Aisheng <aisheng.dong@....com>, Duc Dang <dhdang@....com>,
        Eric Anholt <eric@...olt.net>,
        Fabien Dessenne <fabien.dessenne@...com>,
        Feng Kan <fkan@....com>,
        Florian Fainelli <f.fainelli@...il.com>,
        Georgi Djakov <georgi.djakov@...aro.org>,
        Houlong Wei <houlong.wei@...iatek.com>,
        HS Liao <hs.liao@...iatek.com>,
        Jon Mason <jon.mason@...adcom.com>,
        Kaihua Zhong <zhongkaihua@...wei.com>,
        Kevin Wangtao <kevin.wangtao@...ilicon.com>,
        Lee Jones <lee.jones@...aro.org>, Leo Yan <leo.yan@...aro.org>,
        Ley Foon Tan <lftan@...era.com>,
        Ludovic Barre <ludovic.barre@...com>,
        Neil Armstrong <narmstrong@...libre.com>,
        Nishanth Menon <nm@...com>,
        Oleksij Rempel <o.rempel@...gutronix.de>,
        Ray Jui <ray.jui@...adcom.com>,
        Rob Rice <rob.rice@...adcom.com>,
        Ruyi Wang <wangruyi@...wei.com>,
        Scott Branden <scott.branden@...adcom.com>,
        Sibi Sankar <sibis@...eaurora.org>,
        Stefan Wahren <stefan.wahren@...e.com>,
        Steve Lin <steven.lin1@...adcom.com>,
        Suman Anna <s-anna@...com>, Tony Lindgren <tony@...mide.com>,
        Vikram Prakash <vikram.prakash@...adcom.com>,
        Vladimir Zapolskiy <vz@...ia.com>,
        Sudeep Holla <sudeep.holla@....com>
Subject: Re: [PATCH v2 01/19] mailbox: Add device-managed registration
 functions

On Mon, Dec 17, 2018 at 04:01:59PM +0100, Thierry Reding wrote:
> From: Thierry Reding <treding@...dia.com>
> 
> Add device-managed equivalents of the mbox_controller_register() and
> mbox_controller_unregister() functions that can be used to have the
> devres infrastructure automatically unregister mailbox controllers on
> driver probe failure or driver removal. This can help remove a lot of
> boiler plate code from drivers.
> 
> Signed-off-by: Thierry Reding <treding@...dia.com>
> ---
>  drivers/mailbox/mailbox.c          | 70 ++++++++++++++++++++++++++++++
>  include/linux/mailbox_controller.h |  5 +++
>  2 files changed, 75 insertions(+)
> 
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> index 674b35f402f5..eb781e2b19cb 100644
> --- a/drivers/mailbox/mailbox.c
> +++ b/drivers/mailbox/mailbox.c
> @@ -515,3 +515,73 @@ void mbox_controller_unregister(struct mbox_controller *mbox)
>  	mutex_unlock(&con_mutex);
>  }
>  EXPORT_SYMBOL_GPL(mbox_controller_unregister);
> +
> +static void __devm_mbox_controller_unregister(struct device *dev, void *res)
> +{
> +	struct mbox_controller *mbox = res;
> +
> +	mbox_controller_unregister(mbox);

This looks wrong to me. See below for details.

[...]

> +int devm_mbox_controller_register(struct device *dev,
> +				  struct mbox_controller *mbox)
> +{
> +	struct mbox_controller **ptr;
> +	int err;
> +
> +	ptr = devres_alloc(__devm_mbox_controller_unregister, sizeof(*ptr),
> +			   GFP_KERNEL);

devres_alloc returns devres->data as ptr above

> +	if (!ptr)
> +		return -ENOMEM;
> +
> +	err = mbox_controller_register(mbox);
> +	if (err < 0) {
> +		devres_free(ptr);
> +		return err;
> +	}
> +
> +	devres_add(dev, ptr);
> +	*ptr = mbox;

And ...release is called with devres->data so we need *ptr
in devm_mbox_controller_unregister and not ptr itself something like:

	struct mbox_controller **mbox = res;
	mbox_controller_unregister(*mbox);

With above fixed:

Reviewed-by: Sudeep Holla <sudeep.holla@....com>

--
Regards,
Sudeep