linux-kernel - Re: [PATCH V7 3/9] mailbox: Fix up error handling in mbox_request

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Message-ID: <553FB87B.8000509@ti.com>
Date:	Tue, 28 Apr 2015 11:42:35 -0500
From:	Suman Anna <s-anna@...com>
To:	Andrew Bresticker <abrestic@...omium.org>,
	Stephen Warren <swarren@...dotorg.org>,
	Thierry Reding <thierry.reding@...il.com>,
	Alexandre Courbot <gnurou@...il.com>
CC:	<linux-tegra@...r.kernel.org>, <linux-usb@...r.kernel.org>,
	<devicetree@...r.kernel.org>,
	<linux-arm-kernel@...ts.infradead.org>,
	<linux-kernel@...r.kernel.org>, Benson Leung <bleung@...omium.org>,
	Jassi Brar <jassisinghbrar@...il.com>
Subject: Re: [PATCH V7 3/9] mailbox: Fix up error handling in mbox_request_channel()

On 04/27/2015 05:37 PM, Andrew Bresticker wrote:
> From: Benson Leung <bleung@...omium.org>
> 
> mbox_request_channel() currently returns EBUSY in the event the controller
> is not present or if of_xlate() fails, but in neither case is EBUSY really
> appropriate.  Return EPROBE_DEFER if the controller is not yet present
> and change of_xlate() to return an ERR_PTR instead of NULL so that the
> error can be propagated back to the caller of mbox_request_channel().
> 
> Signed-off-by: Benson Leung <bleung@...omium.org>
> Signed-off-by: Andrew Bresticker <abrestic@...omium.org>
> Cc: Jassi Brar <jassisinghbrar@...il.com>
> Cc: Suman Anna <s-anna@...com>
> ---
> Changes from v6:
>  - Update omap-mailbox's xlate() to return error codes.
> No changes from v5.
> New for v5.
> ---
>  drivers/mailbox/mailbox.c      | 11 ++++++++---
>  drivers/mailbox/omap-mailbox.c |  6 +++---

For the OMAP mailbox portion,
Acked-by: Suman Anna <s-anna@...com>

>  2 files changed, 11 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/mailbox/mailbox.c b/drivers/mailbox/mailbox.c
> index 19b491d..c3c42d4 100644
> --- a/drivers/mailbox/mailbox.c
> +++ b/drivers/mailbox/mailbox.c
> @@ -318,7 +318,7 @@ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
>  		return ERR_PTR(-ENODEV);
>  	}
>  
> -	chan = NULL;
> +	chan = ERR_PTR(-EPROBE_DEFER);
>  	list_for_each_entry(mbox, &mbox_cons, node)
>  		if (mbox->dev->of_node == spec.np) {
>  			chan = mbox->of_xlate(mbox, &spec);
> @@ -327,7 +327,12 @@ struct mbox_chan *mbox_request_channel(struct mbox_client *cl, int index)
>  
>  	of_node_put(spec.np);
>  
> -	if (!chan || chan->cl || !try_module_get(mbox->dev->driver->owner)) {
> +	if (IS_ERR(chan)) {
> +		mutex_unlock(&con_mutex);
> +		return chan;
> +	}
> +
> +	if (chan->cl || !try_module_get(mbox->dev->driver->owner)) {
>  		dev_dbg(dev, "%s: mailbox not free\n", __func__);
>  		mutex_unlock(&con_mutex);
>  		return ERR_PTR(-EBUSY);
> @@ -390,7 +395,7 @@ of_mbox_index_xlate(struct mbox_controller *mbox,
>  	int ind = sp->args[0];
>  
>  	if (ind >= mbox->num_chans)
> -		return NULL;
> +		return ERR_PTR(-EINVAL);
>  
>  	return &mbox->chans[ind];
>  }
> diff --git a/drivers/mailbox/omap-mailbox.c b/drivers/mailbox/omap-mailbox.c
> index 0f332c1..e0df27b 100644
> --- a/drivers/mailbox/omap-mailbox.c
> +++ b/drivers/mailbox/omap-mailbox.c
> @@ -639,18 +639,18 @@ static struct mbox_chan *omap_mbox_of_xlate(struct mbox_controller *controller,
>  
>  	mdev = container_of(controller, struct omap_mbox_device, controller);
>  	if (WARN_ON(!mdev))
> -		return NULL;
> +		return ERR_PTR(-EINVAL);
>  
>  	node = of_find_node_by_phandle(phandle);
>  	if (!node) {
>  		pr_err("%s: could not find node phandle 0x%x\n",
>  		       __func__, phandle);
> -		return NULL;
> +		return ERR_PTR(-ENODEV);
>  	}
>  
>  	mbox = omap_mbox_device_find(mdev, node->name);
>  	of_node_put(node);
> -	return mbox ? mbox->chan : NULL;
> +	return mbox ? mbox->chan : ERR_PTR(-ENOENT);
>  }
>  
>  static int omap_mbox_probe(struct platform_device *pdev)
> 

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