linux-kernel - Re: [PATCH V2 04/15] Drivers: hv: vmbus: Enhance the rescind callback functionality

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Message-ID: <20161206100857.GB32261@kroah.com>
Date:   Tue, 6 Dec 2016 11:08:57 +0100
From:   Greg KH <gregkh@...uxfoundation.org>
To:     kys@...rosoft.com
Cc:     linux-kernel@...r.kernel.org, devel@...uxdriverproject.org,
        olaf@...fle.de, apw@...onical.com, vkuznets@...hat.com,
        jasowang@...hat.com, leann.ogasawara@...onical.com
Subject: Re: [PATCH V2 04/15] Drivers: hv: vmbus: Enhance the rescind
 callback functionality

On Sat, Dec 03, 2016 at 12:34:31PM -0800, kys@...hange.microsoft.com wrote:
> From: K. Y. Srinivasan <kys@...rosoft.com>
> 
> Enhance the rescind callback functionality by permitting the passing of an opaque
> pointer. This functionality will be used by vmbus device drivers to implement
> rescind related cleanup more efficiently.

Eeek, why a void *?  Please make this a _real_ pointer.

> 
> Signed-off-by: K. Y. Srinivasan <kys@...rosoft.com>
> ---
>  drivers/hv/channel_mgmt.c |   11 +++++++----
>  include/linux/hyperv.h    |    7 ++++---
>  2 files changed, 11 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/hv/channel_mgmt.c b/drivers/hv/channel_mgmt.c
> index f9c5827..d83c1ac 100644
> --- a/drivers/hv/channel_mgmt.c
> +++ b/drivers/hv/channel_mgmt.c
> @@ -825,8 +825,10 @@ static void vmbus_onoffer_rescind(struct vmbus_channel_message_header *hdr)
>  
>  	if (channel->device_obj) {
>  		if (channel->chn_rescind_callback) {
> -			channel->chn_rescind_callback(channel);
> -			goto out;
> +			channel->chn_rescind_callback(channel,
> +						      channel->rescind_arg);
> +			if (is_hvsock_channel(channel))
> +				goto out;
>  		}
>  		/*
>  		 * We will have to unregister this device from the
> @@ -1215,9 +1217,10 @@ bool vmbus_are_subchannels_present(struct vmbus_channel *primary)
>  }
>  EXPORT_SYMBOL_GPL(vmbus_are_subchannels_present);
>  
> -void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel,
> -		void (*chn_rescind_cb)(struct vmbus_channel *))
> +void vmbus_set_chn_rescind_callback(struct vmbus_channel *channel, void *arg,
> +		void (*chn_rescind_cb)(struct vmbus_channel *, void *))
>  {
>  	channel->chn_rescind_callback = chn_rescind_cb;
> +	channel->rescind_arg = arg;
>  }
>  EXPORT_SYMBOL_GPL(vmbus_set_chn_rescind_callback);
> diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
> index 35053f9..a9a0ce4 100644
> --- a/include/linux/hyperv.h
> +++ b/include/linux/hyperv.h
> @@ -800,7 +800,8 @@ struct vmbus_channel {
>  	 * Channel rescind callback. Some channels (the hvsock ones), need to
>  	 * register a callback which is invoked in vmbus_onoffer_rescind().
>  	 */
> -	void (*chn_rescind_callback)(struct vmbus_channel *channel);
> +	void (*chn_rescind_callback)(struct vmbus_channel *channel, void *arg);
> +	void *rescind_arg;

Why does the channel have rescind_arg here?

Where do you use this functionality?

thanks,

greg k-h