On Wed, 08 Mar 2023, Jerry Zhang wrote:
> The expiry time field is mean to be expressed in seconds since boot.
Correct.
> The get_expiry() function parses a relative time value in seconds.
Incorrect. It parses and absoulte wall-clock time.
NeilBrown
> In order to get the absolute time of seconds since boot that the given
> message will expire, the right thing is to add seconds_since_boot()
> to the given relative value.
>
> Previously this logic was subtracting boot.tv_sec from the relative
> value, which was causing some confusing behavior. The return type of
> time64_t could possibly underflow if time since boot is greater than
> the passed in relative argument. Also several checks in nfs code compare
> the return value to 0 to indicate failure, and this could spuriously
> be tripped if seconds since boot happened to match the argument.
>
> Fixes: c5b29f885afe ("sunrpc: use seconds since boot in expiry cache")
> Signed-off-by: Jerry Zhang <Jerry@xxxxxxxxxx>
> ---
> include/linux/sunrpc/cache.h | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> diff --git a/include/linux/sunrpc/cache.h b/include/linux/sunrpc/cache.h
> index ec5a555df96f..b96b1319c93d 100644
> --- a/include/linux/sunrpc/cache.h
> +++ b/include/linux/sunrpc/cache.h
> @@ -301,16 +301,14 @@ static inline int get_time(char **bpp, time64_t *time)
> }
>
> static inline time64_t get_expiry(char **bpp)
> {
> time64_t rv;
> - struct timespec64 boot;
>
> if (get_time(bpp, &rv))
> return 0;
> if (rv < 0)
> return 0;
> - getboottime64(&boot);
> - return rv - boot.tv_sec;
> + return rv + seconds_since_boot();
> }
>
> #endif /* _LINUX_SUNRPC_CACHE_H_ */
> --
> 2.37.3
>
>
