linux-kernel - Re: [PATCH v3 15/18] xen/pvcalls: implement the ioworker functions

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Message-ID: <51e3bbad-d5f2-a3b9-b038-4535cd58ea2a@suse.com>
Date:   Tue, 13 Jun 2017 09:51:39 +0200
From:   Juergen Gross <jgross@...e.com>
To:     Stefano Stabellini <sstabellini@...nel.org>,
        xen-devel@...ts.xen.org
Cc:     linux-kernel@...r.kernel.org, boris.ostrovsky@...cle.com,
        Stefano Stabellini <stefano@...reto.com>
Subject: Re: [PATCH v3 15/18] xen/pvcalls: implement the ioworker functions

On 02/06/17 21:31, Stefano Stabellini wrote:
> We have one ioworker per socket. Each ioworker goes through the list of
> outstanding read/write requests. Once all requests have been dealt with,
> it returns.
> 
> We use one atomic counter per socket for "read" operations and one
> for "write" operations to keep track of the reads/writes to do.
> 
> We also use one atomic counter ("io") per ioworker to keep track of how
> many outstanding requests we have in total assigned to the ioworker. The
> ioworker finishes when there are none.
> 
> Signed-off-by: Stefano Stabellini <stefano@...reto.com>
> CC: boris.ostrovsky@...cle.com
> CC: jgross@...e.com
> ---
>  drivers/xen/pvcalls-back.c | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/drivers/xen/pvcalls-back.c b/drivers/xen/pvcalls-back.c
> index 6afe7a0..0283d49 100644
> --- a/drivers/xen/pvcalls-back.c
> +++ b/drivers/xen/pvcalls-back.c
> @@ -99,8 +99,35 @@ static int pvcalls_back_release_active(struct xenbus_device *dev,
>  				       struct pvcalls_fedata *priv,
>  				       struct sock_mapping *map);
>  
> +static void pvcalls_conn_back_read(unsigned long opaque)

Why not void *opaque? You could drop the cast below then.


Juergen

> +{
> +}
> +
> +static int pvcalls_conn_back_write(struct sock_mapping *map)
> +{
> +	return 0;
> +}
> +
>  static void pvcalls_back_ioworker(struct work_struct *work)
>  {
> +	struct pvcalls_ioworker *ioworker = container_of(work,
> +		struct pvcalls_ioworker, register_work);
> +	struct sock_mapping *map = container_of(ioworker, struct sock_mapping,
> +		ioworker);
> +
> +	while (atomic_read(&map->io) > 0) {
> +		if (atomic_read(&map->release) > 0) {
> +			atomic_set(&map->release, 0);
> +			return;
> +		}
> +
> +		if (atomic_read(&map->read) > 0)
> +			pvcalls_conn_back_read((unsigned long)map);
> +		if (atomic_read(&map->write) > 0)
> +			pvcalls_conn_back_write(map);
> +
> +		atomic_dec(&map->io);
> +	}
>  }
>  
>  static int pvcalls_back_socket(struct xenbus_device *dev,
>