[LTP] [PATCH 1/2] Add TST_SPIN_TEST() macro

[Richard Palethorpe <rpalethorpe@suse.de>]

Hi,

Martin Doucha <mdoucha@suse.cz> writes:

> The TST_RETRY_FUNC() macro requires a single return value that'll be considered
> success. This cannot be used with system calls that e.g. return a new file
> descriptor because the success value is somewhat unpredictable.
>
> Add a new macro TST_SPIN_TEST that'll work mostly like TST_RETRY_FUNC(), except:
> - Any negative return value means failure, any non-negative return value means
>   success.
> - The loop will fall through on timeout instead of callid tst_brk(). TST_RET
>   and TST_ERR will be set to the values returned by the last FUNC call.
>
> Signed-off-by: Martin Doucha <mdoucha@suse.cz>
> ---
>  include/tst_common.h | 28 ++++++++++++++++++++++++++++
>  1 file changed, 28 insertions(+)
>
> diff --git a/include/tst_common.h b/include/tst_common.h
> index a0c06a3f7..72e00ca81 100644
> --- a/include/tst_common.h
> +++ b/include/tst_common.h
> @@ -55,6 +55,34 @@
>  	ERET;								\
>  })
>
> +/**
> + * TST_SPIN_TEST() - Repeatedly retry a function with an increasing delay.
> + * @FUNC - The function which will be retried
> + *
> + * Same as TST_RETRY_FUNC() but any non-negative return value is accepted
> + * as success and tst_brk() will not be called on timeout.
> + */
> +#define TST_SPIN_TEST(FUNC) \
> +	TST_SPIN_TEST_EXP_BACKOFF(FUNC, 1, -1)

Ah, so this is actually always exponential. Ignore my comment on other
patch.

> +
> +#define TST_SPIN_TEST_EXP_BACKOFF(FUNC, MAX_DELAY, GOOD_ERRNO)	\
> +({	unsigned int tst_delay_, tst_max_delay_;			\
> +	tst_delay_ = 1;							\
> +	tst_max_delay_ = tst_multiply_timeout(MAX_DELAY * 1000000);	\
> +	for (;;) {							\
> +		TEST(FUNC);						\
> +		if (TST_RET >= 0 || (GOOD_ERRNO >= 0 && TST_ERR == GOOD_ERRNO))	\
> +			break;						\
> +		if (tst_delay_ < tst_max_delay_) {			\
> +			usleep(tst_delay_);				\
> +			tst_delay_ *= 2;				\
> +		} else {						\
> +			break;						\
> +		}							\
> +	}								\
> +	TST_RET;							\
> +})
> +
>  #define TST_BRK_SUPPORTS_ONLY_TCONF_TBROK(condition) \
>  	do { ((void)sizeof(char[1 - 2 * !!(condition)])); } while (0)
>
> --
> 2.24.1


--
Thank you,
Richard.