[v2,0/4] cpufreq: qcom-hw: Fixes for cpu hotplug support

This patchseries aims at fixing and improving CPU hotplug support on
Qualcomm platforms. First three patches are the fixes for the LMH
support in the cpufreq driver. The last patch adds support for
lightweight offline() and online() callbacks which are used instead of
exit() and init() each time the CPU is put offline or back online.

Changes since v1:
- Update commit message for the first patch to describe why dropping
  affinity hint is required (before calling free_irq()),
- Fixed commit message for the second patch to include messages
  generated using the mainline kernel w/o additional patches,
- Changed third patch to use dev_warn_ratelimited(),
- Reworked last patch to move request_irq/free_irq to online()/offline()
  to make sure that the IRQ isn't left enabled after the CPU has been
  put offline.

Dmitry Baryshkov (4):
  cpufreq: qcom-hw: drop affinity hint before freeing the IRQ
  cpufreq: qcom-hw: fix the race between LMH worker and cpuhp
  cpufreq: qcom-hw: fix the opp entries refcounting
  cpufreq: qcom-hw: provide online/offline operations

 drivers/cpufreq/qcom-cpufreq-hw.c | 78 +++++++++++++++++++++++++------
 1 file changed, 64 insertions(+), 14 deletions(-)

Hi Dmitry,

On 3/10/22 12:39 AM, Dmitry Baryshkov wrote:
> Drop affinity hint before freeing the throttling IRQ to fix the
> following trace. One is not allowed to call free_irq() with an affinity
> hint in place (which was set by qcom_cpufreq_hw_lmh_init()).
> 
> [  185.114773] ------------[ cut here ]------------
> [  185.119517] WARNING: CPU: 7 PID: 43 at kernel/irq/manage.c:1887 free_irq+0x3a4/0x3dc
> [  185.127474] Modules linked in:
> [  185.130618] CPU: 7 PID: 43 Comm: cpuhp/7 Tainted: G S      W         5.17.0-rc6-00386-g67382a5b705d-dirty #690
> [  185.147125] pstate: 604000c5 (nZCv daIF +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [  185.154269] pc : free_irq+0x3a4/0x3dc
> [  185.158031] lr : free_irq+0x33c/0x3dc
> [  185.161792] sp : ffff80000841bc90
> [  185.165195] x29: ffff80000841bc90 x28: ffffa6edc5c3d000 x27: ffff6d93729e5908
> [  185.172515] x26: 0000000000000000 x25: ffff6d910109fc00 x24: ffff6d91011490e0
> [  185.179838] x23: ffff6d9101149218 x22: 0000000000000080 x21: 0000000000000000
> [  185.187163] x20: ffff6d9101149000 x19: ffff6d910ab61500 x18: ffffffffffffffff
> [  185.194487] x17: 2e35202020202020 x16: 2020202020202020 x15: ffff80008841b9a7
> [  185.201805] x14: 00000000000003c9 x13: 0000000000000001 x12: 0000000000000040
> [  185.209135] x11: ffff6d91005aab58 x10: ffff6d91005aab5a x9 : ffffc6a5ad1c5408
> [  185.216455] x8 : ffff6d91005adb88 x7 : 0000000000000000 x6 : ffffc6a5ab5a91f4
> [  185.223776] x5 : 0000000000000000 x4 : ffff6d91011490a8 x3 : ffffc6a5ad266108
> [  185.231098] x2 : 0000000013033204 x1 : ffff6d9101149000 x0 : ffff6d910a9cc000
> [  185.238421] Call trace:
> [  185.240932]  free_irq+0x3a4/0x3dc
> [  185.244334]  qcom_cpufreq_hw_cpu_exit+0x78/0xcc
> [  185.248985]  cpufreq_offline.isra.0+0x228/0x270
> [  185.253639]  cpuhp_cpufreq_offline+0x10/0x20
> [  185.258027]  cpuhp_invoke_callback+0x16c/0x2b0
> [  185.262592]  cpuhp_thread_fun+0x190/0x250
> [  185.266710]  smpboot_thread_fn+0x12c/0x230
> [  185.270914]  kthread+0xfc/0x100
> [  185.274145]  ret_from_fork+0x10/0x20
> [  185.277820] irq event stamp: 212
> [  185.281136] hardirqs last  enabled at (211): [<ffffc6a5ac57973c>] _raw_spin_unlock_irqrestore+0x8c/0xa0
> [  185.290775] hardirqs last disabled at (212): [<ffffc6a5ac572100>] __schedule+0x710/0xa10
> [  185.299081] softirqs last  enabled at (0): [<ffffc6a5ab50f7b0>] copy_process+0x7d0/0x1a14
> [  185.307475] softirqs last disabled at (0): [<0000000000000000>] 0x0
> 
> Fixes: 275157b367f4 ("cpufreq: qcom-cpufreq-hw: Add dcvs interrupt support")

I suppose the fixed commit is 3ed6dfbd3bb98 ("cpufreq: qcom-hw: Set CPU affinity of dcvsh interrupts")

Otherwise looks correct.

> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
> ---
>   drivers/cpufreq/qcom-cpufreq-hw.c | 1 +
>   1 file changed, 1 insertion(+)
> 
> diff --git a/drivers/cpufreq/qcom-cpufreq-hw.c b/drivers/cpufreq/qcom-cpufreq-hw.c
> index 618e436018c0..44d46e52baea 100644
> --- a/drivers/cpufreq/qcom-cpufreq-hw.c
> +++ b/drivers/cpufreq/qcom-cpufreq-hw.c
> @@ -427,6 +427,7 @@ static void qcom_cpufreq_hw_lmh_exit(struct qcom_cpufreq_data *data)
>   	mutex_unlock(&data->throttle_lock);
>   
>   	cancel_delayed_work_sync(&data->throttle_work);
> +	irq_set_affinity_hint(data->throttle_irq, NULL);
>   	free_irq(data->throttle_irq, data);
>   }
>   
> 

--
Best wishes,
Vladimir