Re: [PATCH v2] fix overflow in idle exit_latency

[AngeloGioacchino Del Regno]

Il 19/12/23 04:14, Bo Ye ha scritto:
> From: C Cheng <C.Cheng@xxxxxxxxxxxx>
>
> In detail:
>
> In C language, when you perform a multiplication operation, if
> both operands are of int type, the multiplication operation is
> performed on the int type, and then the result is converted to
> the target type. This means that if the product of int type
> multiplication exceeds the range that int type can represent,
>   an overflow will occur even if you store the result in a
> variable of int64_t type.
>
> For a multiplication of two int values, it is better to use
> mul_u32_u32() rather than s->exit_latency_ns = s->exit_latency *
> NSEC_PER_USEC to avoid potential overflow happenning.
>
> Signed-off-by: C Cheng <C.Cheng@xxxxxxxxxxxx>
> Signed-off-by: Bo Ye <bo.ye@xxxxxxxxxxxx>

Reviewed-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@xxxxxxxxxxxxx>