[PATCH] dm: rtc: Avoid a race in the rtc_reset test

[Heinrich Schuchardt]

On 7/31/22 20:27, Simon Glass wrote:
> Since resetting the RTC on sandbox causes it to read the base time from
> the system, we cannot rely on this being unchanged since it was last read.
> Allow for a one-second delay.
>
> Fixes: https://source.denx.de/u-boot/u-boot/-/issues/4
> Reported-by: Bin Meng <bmeng.cn at gmail.com>
> Reported-by: Tom Rini <trini at konsulko.com>
> Suggested-by: Rasmus Villemoes <rasmus.villemoes at prevas.dk>
> Signed-off-by: Simon Glass <sjg at chromium.org>
> ---
>
>   test/dm/rtc.c | 11 ++++++++---
>   1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/test/dm/rtc.c b/test/dm/rtc.c
> index c7f9f8f0ce7..403bf5c640a 100644
> --- a/test/dm/rtc.c
> +++ b/test/dm/rtc.c
> @@ -245,16 +245,21 @@ static int dm_test_rtc_reset(struct unit_test_state *uts)
>   	ut_assertok(dm_rtc_get(dev, &now));
>
>   	ut_assertok(i2c_emul_find(dev, &emul));
> -	ut_assert(emul != NULL);
> +	ut_assertnonnull(emul);

This is an unrelated change. It would be preferable to describe it in
the commit message.

>
>   	old_base_time = sandbox_i2c_rtc_get_set_base_time(emul, 0);
>
>   	ut_asserteq(0, sandbox_i2c_rtc_get_set_base_time(emul, -1));
>
> -	/* Resetting the RTC should put he base time back to normal */
> +	/*
> +	 * Resetting the RTC should put the base time back to normal. Allow for
> +	 * a one-second adjustment in case the time flips over while this
> +	 * test process is pre-empted, since reset_time() in i2c_rtc_emul.c
> +	 * reads the time from the OS.
> +	 */
>   	ut_assertok(dm_rtc_reset(dev));
>   	base_time = sandbox_i2c_rtc_get_set_base_time(emul, -1);
> -	ut_asserteq(old_base_time, base_time);
> +	ut_assert(base_time - old_base_time <= 1);

If the operating system uses daylight saving time, this may still fail
(very rarely).

How about using gmtime() instead of localtime()? But that would be a
separate patch.

Reviewed-by: Heinrich Schuchardt <xypron.glpk at gmx.de>

>
>   	return 0;
>   }