[PATCH 08/17] linux/compat.h: Add wait_event_timeout macro

[Heinrich Schuchardt <xypron.glpk@gmx.de>]

On 7/1/20 6:29 PM, Anastasiia Lukianenko wrote:
> From: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
>
> Add  wait_event_timeout - sleep until a condition gets true or a
> timeout elapses.
>
> This is a stripped version of the same from Linux kernel with the
> following u-boot specific modifications:
> - no wait queues supported
> - use u-boot timer to detect timeouts
> - check for Ctrl-C pressed during wait
>
> Signed-off-by: Oleksandr Andrushchenko <oleksandr_andrushchenko@epam.com>
> Signed-off-by: Anastasiia Lukianenko <anastasiia_lukianenko@epam.com>
> ---
>  include/linux/compat.h | 45 ++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 45 insertions(+)
>
> diff --git a/include/linux/compat.h b/include/linux/compat.h
> index 712eeaef4e..5375b7d3b8 100644
> --- a/include/linux/compat.h
> +++ b/include/linux/compat.h
> @@ -1,12 +1,20 @@
>  #ifndef _LINUX_COMPAT_H_
>  #define _LINUX_COMPAT_H_
>
> +#include <console.h>
>  #include <log.h>
>  #include <malloc.h>
> +
> +#include <asm/processor.h>
> +
>  #include <linux/types.h>
>  #include <linux/err.h>
>  #include <linux/kernel.h>
>
> +#ifdef CONFIG_XEN
> +#include <xen/events.h>
> +#endif
> +
>  struct unused {};
>  typedef struct unused unused_t;
>
> @@ -122,6 +130,43 @@ static inline void kmem_cache_destroy(struct kmem_cache *cachep)
>  #define add_wait_queue(...)	do { } while (0)
>  #define remove_wait_queue(...)	do { } while (0)
>
> +#ifndef CONFIG_XEN
> +#define eventchn_poll()
> +#endif
> +
> +#define __wait_event_timeout(condition, timeout, ret)		\
> +({								\
> +	ulong __ret = ret; /* explicit shadow */		\
> +	ulong start = get_timer(0);				\
> +	for (;;) {						\
> +		eventchn_poll();				\
> +		if (condition) {				\
> +			__ret = 1;				\
> +			break;					\
> +	}							\
> +	if ((get_timer(start) > timeout) || ctrlc()) {		\
> +		__ret = 0;					\
> +		break;						\
> +	}							\
> +	cpu_relax();						\
> +	}							\
> +	__ret;							\
> +})
> +
> +/*
> + * 0 if the @condition evaluated to %false after the @timeout elapsed,
> + * 1 if the @condition evaluated to %true
> + */

Please, document all arguments. Use Sphinx style as in

https://www.kernel.org/doc/html/latest/doc-guide/kernel-doc.html#function-documentation.

Best regards

Heinrich.

> +#define wait_event_timeout(wq_head, condition, timeout)			\
> +({									\
> +	ulong __ret;							\
> +	if (condition)							\
> +		__ret = 1;						\
> +	else								\
> +		__ret = __wait_event_timeout(condition, timeout, __ret);\
> +	__ret;								\
> +})
> +
>  #define KERNEL_VERSION(a,b,c)	(((a) << 16) + ((b) << 8) + (c))
>
>  /* This is also defined in ARMv8's mmu.h */
>