linux-kernel - Re: [char-misc-next RESEND] mei: bus: enable non-blocking RX

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Date:   Tue, 6 Dec 2016 11:05:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     Tomas Winkler <tomas.winkler@...el.com>
Cc:     Alexander Usyskin <alexander.usyskin@...el.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [char-misc-next RESEND] mei: bus: enable non-blocking RX

On Sat, Dec 03, 2016 at 12:15:25AM +0200, Tomas Winkler wrote:
> From: Alexander Usyskin <alexander.usyskin@...el.com>
> 
> Enable non-blocking receive for drivers on mei bus, this allows checking
> for data availability by mei client drivers. This is most effective for
> fixed address clients, that lacks flow control.
> 
> This function adds new API function mei_cldev_recv_nonblock(), it
> retuns -EGAIN if function will block.
> 
> Signed-off-by: Alexander Usyskin <alexander.usyskin@...el.com>
> Signed-off-by: Tomas Winkler <tomas.winkler@...el.com>
> ---
>  drivers/misc/mei/bus-fixup.c |  4 ++--
>  drivers/misc/mei/bus.c       | 31 +++++++++++++++++++++++++++++--
>  drivers/misc/mei/mei_dev.h   |  7 ++++++-
>  include/linux/mei_cl_bus.h   |  6 ++++--
>  4 files changed, 41 insertions(+), 7 deletions(-)
> 
> diff --git a/drivers/misc/mei/bus-fixup.c b/drivers/misc/mei/bus-fixup.c
> index 7f2cef9011ae..18e05ca7584f 100644
> --- a/drivers/misc/mei/bus-fixup.c
> +++ b/drivers/misc/mei/bus-fixup.c
> @@ -141,7 +141,7 @@ static int mei_osver(struct mei_cl_device *cldev)
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = __mei_cl_recv(cldev->cl, buf, length);
> +	ret = __mei_cl_recv(cldev->cl, buf, length, 0);
>  	if (ret < 0)
>  		return ret;
>  
> @@ -272,7 +272,7 @@ static int mei_nfc_if_version(struct mei_cl *cl,
>  		return -ENOMEM;
>  
>  	ret = 0;
> -	bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length);
> +	bytes_recv = __mei_cl_recv(cl, (u8 *)reply, if_version_length, 0);

I still don't like this, as here are two examples of you having to
somehow mentally keep track of the "mode" of what is going on.

But it's your code, you have to maintain it, not me, good luck!

greg k-h