Why did you put a Fixes; tag in the subject?
Please provide a proper subject and put the Fixes: tag next to the
Signed-off-by: one below.
On Mon, Aug 26, 2024 at 11:07 AM Yanhao Dong <570260087@xxxxxx> wrote:
>
> From: ysay <ysaydong@xxxxxxxxx>
>
> When guest_halt_poll_allow_shrink=N,setting guest_halt_poll_ns
> from a large value to 0 does not reset the CPU polling time,
> despite guest_halt_poll_ns being intended as a mandatory maximum
> time limit.
>
> The problem was situated in the adjust_poll_limit() within
> drivers/cpuidle/governors/haltpoll.c:79.
>
> Specifically, when guest_halt_poll_allow_shrink was set to N,
> resetting guest_halt_poll_ns to zero did not lead to executing any
> section of code that adjusts dev->poll_limit_ns.
>
> The issue has been resolved by relocating the check and assignment for
> dev->poll_limit_ns outside of the conditional block.
> This ensures that every modification to guest_halt_poll_ns
> properly influences the CPU polling time.
>
> Signed-off-by: ysay <ysaydong@xxxxxxxxx>
> ---
> drivers/cpuidle/governors/haltpoll.c | 14 +++++++-------
> 1 file changed, 7 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/cpuidle/governors/haltpoll.c b/drivers/cpuidle/governors/haltpoll.c
> index 663b7f164..99c6260d7 100644
> --- a/drivers/cpuidle/governors/haltpoll.c
> +++ b/drivers/cpuidle/governors/haltpoll.c
> @@ -78,26 +78,22 @@ static int haltpoll_select(struct cpuidle_driver *drv,
>
> static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns)
> {
> - unsigned int val;
> + unsigned int val = dev->poll_limit_ns;
>
> /* Grow cpu_halt_poll_us if
> * cpu_halt_poll_us < block_ns < guest_halt_poll_us
> */
> if (block_ns > dev->poll_limit_ns && block_ns <= guest_halt_poll_ns) {
> - val = dev->poll_limit_ns * guest_halt_poll_grow;
> + val *= guest_halt_poll_grow;
>
> if (val < guest_halt_poll_grow_start)
> val = guest_halt_poll_grow_start;
> - if (val > guest_halt_poll_ns)
> - val = guest_halt_poll_ns;
>
> trace_guest_halt_poll_ns_grow(val, dev->poll_limit_ns);
> - dev->poll_limit_ns = val;
> } else if (block_ns > guest_halt_poll_ns &&
> guest_halt_poll_allow_shrink) {
> unsigned int shrink = guest_halt_poll_shrink;
>
> - val = dev->poll_limit_ns;
> if (shrink == 0) {
> val = 0;
> } else {
> @@ -108,8 +104,12 @@ static void adjust_poll_limit(struct cpuidle_device *dev, u64 block_ns)
> }
>
> trace_guest_halt_poll_ns_shrink(val, dev->poll_limit_ns);
> - dev->poll_limit_ns = val;
> }
> +
> + if (val > guest_halt_poll_ns)
> + val = guest_halt_poll_ns;
> +
> + dev->poll_limit_ns = val;
> }
>
> /**
> --
> 2.43.5
>
>
