[PATCH v7 3/5] counter: Add character device interface

[Oleksij Rempel]

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 at lechnology.com>
> Cc: Gwendal Grignou <gwendal at chromium.org>
> Cc: Dan Carpenter <dan.carpenter at oracle.com>
> Signed-off-by: William Breathitt Gray <vilhelm.gray at 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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