linux-kernel - Re: [PATCH] uio: add uio_event

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Date:	Wed, 14 Aug 2013 11:34:57 -0700
From:	Greg KH <gregkh@...uxfoundation.org>
To:	Xiaolong Ye <yexl@...vell.com>
Cc:	hjk@...sjkoch.de, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] uio: add uio_event_sync interface

On Wed, Aug 14, 2013 at 08:30:23PM +0800, Xiaolong Ye wrote:
> This interface is called to sync listener->event_count and device
> event count in multi-instances case.
> 
> Change-Id: Ibb1e4888ce55b4993394b61e4bcd6dce8b8291f0

What is this for?  (hint, it should never be in a kernel patch...)

> Signed-off-by: Xiaolong Ye <yexl@...vell.com>
> ---
>  drivers/uio/uio.c          |   12 ++++++++++++
>  include/linux/uio_driver.h |    1 +
>  2 files changed, 13 insertions(+)
> 
> diff --git a/drivers/uio/uio.c b/drivers/uio/uio.c
> index ba47563..95d559f 100644
> --- a/drivers/uio/uio.c
> +++ b/drivers/uio/uio.c
> @@ -408,6 +408,18 @@ void uio_event_notify(struct uio_info *info)
>  EXPORT_SYMBOL_GPL(uio_event_notify);
>  
>  /**
> + * uio_event_sync - sync listener's event count with UIO device
> + * @listener: uio_listener structure
> + */
> +void uio_event_sync(struct uio_listener *listener)
> +{
> +	struct uio_device *idev = listener->dev;
> +
> +	listener->event_count = atomic_read(&idev->event);

What prevents that count from changing right after you call this
function?

> +}
> +EXPORT_SYMBOL_GPL(uio_event_sync);

You are exporting a symbol, yet never using it, which means I can't
accept this patch, sorry.

greg k-h
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