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Date:   Thu, 28 Jan 2021 10:01:13 +0100
From:   Oleksij Rempel <o.rempel@pengutronix.de>
To:     William Breathitt Gray <vilhelm.gray@gmail.com>
Cc:     jic23@kernel.org, kamel.bouhara@bootlin.com, gwendal@chromium.org,
        a.fatoum@pengutronix.de, david@lechnology.com,
        linux-iio@vger.kernel.org, patrick.havelange@essensium.com,
        alexandre.belloni@bootlin.com, mcoquelin.stm32@gmail.com,
        linux-kernel@vger.kernel.org,
        Dan Carpenter <dan.carpenter@oracle.com>,
        kernel@pengutronix.de, fabrice.gasnier@st.com,
        syednwaris@gmail.com, linux-stm32@st-md-mailman.stormreply.com,
        linux-arm-kernel@lists.infradead.org, alexandre.torgue@st.com
Subject: Re: [PATCH v7 3/5] counter: Add character device interface
Message-ID: <20210128090113.GA8734@pengutronix.de>
References: <cover.1608935587.git.vilhelm.gray@gmail.com>
 <57bc509273bf288d74835e6ebdaebf27b4991888.1608935587.git.vilhelm.gray@gmail.com>
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Hello William,


On Fri, Dec 25, 2020 at 07:15:36PM -0500, William Breathitt Gray wrote:
> This patch introduces a character device interface for the Counter
> subsystem. Device data is exposed through standard character device read
> operations. Device data is gathered when a Counter event is pushed by
> the respective Counter device driver. Configuration is handled via ioctl
> operations on the respective Counter character device node.
> 
> Cc: David Lechner <david@lechnology.com>
> Cc: Gwendal Grignou <gwendal@chromium.org>
> Cc: Dan Carpenter <dan.carpenter@oracle.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray@gmail.com>
> ---
...
> +struct counter_event {
> +	__aligned_u64 timestamp;
> +	__aligned_u64 value;
> +	struct counter_watch watch;
> +	__u8 errno;

This variable clashed in user space, as soon as you include errno.h,
with the libc's "magic" definition of errno. What about "err" instead.
I'm not sure it an __u8 is the proper type, IIRC usually it's an int.

Regards,
Oleksij
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