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SubjectRe: [PATCH v5 1/5] soc: qcom: rpmh-rsc: Correctly ignore CPU_CLUSTER_PM notifications
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Hi,

On 4/24/2020 10:16 PM, Douglas Anderson wrote:
> Our switch statement doesn't have entries for CPU_CLUSTER_PM_ENTER,
> CPU_CLUSTER_PM_ENTER_FAILED, and CPU_CLUSTER_PM_EXIT and doesn't have
> a default. This means that we'll try to do a flush in those cases but
> we won't necessarily be the last CPU down. That's not so ideal since
> our (lack of) locking assumes we're on the last CPU.
>
> Luckily this isn't as big a problem as you'd think since (at least on
> the SoC I tested) we don't get these notifications except on full
> system suspend. ...and on full system suspend we get them on the last
> CPU down. That means that the worst problem we hit is flushing twice.
> Still, it's good to make it correct.
>
> Fixes: 985427f997b6 ("soc: qcom: rpmh: Invoke rpmh_flush() for dirty caches")
> Reported-by: Stephen Boyd <swboyd@chromium.org>
> Signed-off-by: Douglas Anderson <dianders@chromium.org>
> Reviewed-by: Maulik Shah <mkshah@codeaurora.org>
> Reviewed-by: Stephen Boyd <swboyd@chromium.org>
> ---
>
> Changes in v5:
> - Corrently => Correctly
>
> Changes in v4:
> - ("...Corrently ignore CPU_CLUSTER_PM notifications") split out for v4.
>
> Changes in v3: None
> Changes in v2: None
>
> drivers/soc/qcom/rpmh-rsc.c | 2 ++
> 1 file changed, 2 insertions(+)
>
> diff --git a/drivers/soc/qcom/rpmh-rsc.c b/drivers/soc/qcom/rpmh-rsc.c
> index a9e15699f55f..3571a99fc839 100644
> --- a/drivers/soc/qcom/rpmh-rsc.c
> +++ b/drivers/soc/qcom/rpmh-rsc.c
> @@ -806,6 +806,8 @@ static int rpmh_rsc_cpu_pm_callback(struct notifier_block *nfb,
> case CPU_PM_EXIT:
> cpumask_clear_cpu(smp_processor_id(), &drv->cpus_entered_pm);
> goto exit;
> + default:
> + return NOTIFY_DONE;

I noticed a bug here,

Either need to unlock and return here.

+ default:
+               ret = NOTIFY_DONE;
+ goto exit;

Or

If you move this patch at the end of series, it should will work fine as is.
Since in patch 5 of this series,  pm_lock is removed, so return
NOTIFY_DONE; do not any unlock.

When i pulled in only first two changes in this series i got spinlock
recursion during suspend-resume.
Back when i pull in entire series for validation, the issue do not come
because last patch removes pm_lock.

Thanks,
Maulik
> }
>
> ret = rpmh_rsc_ctrlr_is_busy(drv);

--
QUALCOMM INDIA, on behalf of Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by The Linux Foundation

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