linux-kernel - Re: [PATCH] PM: core: keep irq flags in device_pm_check

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Date:   Thu, 10 Mar 2022 19:41:24 +0100
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Linux PM <linux-pm@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] PM: core: keep irq flags in device_pm_check_callbacks

On Sat, Mar 5, 2022 at 12:02 PM Dmitry Baryshkov
<dmitry.baryshkov@...aro.org> wrote:
>
> The function device_pm_check_callbacks() can be called under the spin
> lock (in the reported case it happens from genpd_add_device() ->
> dev_pm_domain_set(), when the genpd uses spinlocks rather than mutexes.
>
> However this function uncoditionally uses spin_lock_irq() /
> spin_unlock_irq(), thus not preserving the CPU flags. Use the
> irqsave/irqrestore instead.
>
> The backtrace for the reference:
> [    2.752010] ------------[ cut here ]------------
> [    2.756769] raw_local_irq_restore() called with IRQs enabled
> [    2.762596] WARNING: CPU: 4 PID: 1 at kernel/locking/irqflag-debug.c:10 warn_bogus_irq_restore+0x34/0x50
> [    2.772338] Modules linked in:
> [    2.775487] CPU: 4 PID: 1 Comm: swapper/0 Tainted: G S                5.17.0-rc6-00384-ge330d0d82eff-dirty #684
> [    2.781384] Freeing initrd memory: 46024K
> [    2.785839] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
> [    2.785841] pc : warn_bogus_irq_restore+0x34/0x50
> [    2.785844] lr : warn_bogus_irq_restore+0x34/0x50
> [    2.785846] sp : ffff80000805b7d0
> [    2.785847] x29: ffff80000805b7d0 x28: 0000000000000000 x27: 0000000000000002
> [    2.785850] x26: ffffd40e80930b18 x25: ffff7ee2329192b8 x24: ffff7edfc9f60800
> [    2.785853] x23: ffffd40e80930b18 x22: ffffd40e80930d30 x21: ffff7edfc0dffa00
> [    2.785856] x20: ffff7edfc09e3768 x19: 0000000000000000 x18: ffffffffffffffff
> [    2.845775] x17: 6572206f74206465 x16: 6c696166203a3030 x15: ffff80008805b4f7
> [    2.853108] x14: 0000000000000000 x13: ffffd40e809550b0 x12: 00000000000003d8
> [    2.860441] x11: 0000000000000148 x10: ffffd40e809550b0 x9 : ffffd40e809550b0
> [    2.867774] x8 : 00000000ffffefff x7 : ffffd40e809ad0b0 x6 : ffffd40e809ad0b0
> [    2.875107] x5 : 000000000000bff4 x4 : 0000000000000000 x3 : 0000000000000000
> [    2.882440] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff7edfc03a8000
> [    2.889774] Call trace:
> [    2.892290]  warn_bogus_irq_restore+0x34/0x50
> [    2.896770]  _raw_spin_unlock_irqrestore+0x94/0xa0
> [    2.901690]  genpd_unlock_spin+0x20/0x30
> [    2.905724]  genpd_add_device+0x100/0x2d0
> [    2.909850]  __genpd_dev_pm_attach+0xa8/0x23c
> [    2.914329]  genpd_dev_pm_attach_by_id+0xc4/0x190
> [    2.919167]  genpd_dev_pm_attach_by_name+0x3c/0xd0
> [    2.924086]  dev_pm_domain_attach_by_name+0x24/0x30
> [    2.929102]  psci_dt_attach_cpu+0x24/0x90
> [    2.933230]  psci_cpuidle_probe+0x2d4/0x46c
> [    2.937534]  platform_probe+0x68/0xe0
> [    2.941304]  really_probe.part.0+0x9c/0x2fc
> [    2.945605]  __driver_probe_device+0x98/0x144
> [    2.950085]  driver_probe_device+0x44/0x15c
> [    2.954385]  __device_attach_driver+0xb8/0x120
> [    2.958950]  bus_for_each_drv+0x78/0xd0
> [    2.962896]  __device_attach+0xd8/0x180
> [    2.966843]  device_initial_probe+0x14/0x20
> [    2.971144]  bus_probe_device+0x9c/0xa4
> [    2.975092]  device_add+0x380/0x88c
> [    2.978679]  platform_device_add+0x114/0x234
> [    2.983067]  platform_device_register_full+0x100/0x190
> [    2.988344]  psci_idle_init+0x6c/0xb0
> [    2.992113]  do_one_initcall+0x74/0x3a0
> [    2.996060]  kernel_init_freeable+0x2fc/0x384
> [    3.000543]  kernel_init+0x28/0x130
> [    3.004132]  ret_from_fork+0x10/0x20
> [    3.007817] irq event stamp: 319826
> [    3.011404] hardirqs last  enabled at (319825): [<ffffd40e7eda0268>] __up_console_sem+0x78/0x84
> [    3.020332] hardirqs last disabled at (319826): [<ffffd40e7fd6d9d8>] el1_dbg+0x24/0x8c
> [    3.028458] softirqs last  enabled at (318312): [<ffffd40e7ec90410>] _stext+0x410/0x588
> [    3.036678] softirqs last disabled at (318299): [<ffffd40e7ed1bf68>] __irq_exit_rcu+0x158/0x174
> [    3.045607] ---[ end trace 0000000000000000 ]---
>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@...aro.org>
> ---
>  drivers/base/power/main.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/base/power/main.c b/drivers/base/power/main.c
> index 04ea92cbd9cf..08c8a69d7b81 100644
> --- a/drivers/base/power/main.c
> +++ b/drivers/base/power/main.c
> @@ -2018,7 +2018,9 @@ static bool pm_ops_is_empty(const struct dev_pm_ops *ops)
>
>  void device_pm_check_callbacks(struct device *dev)
>  {
> -       spin_lock_irq(&dev->power.lock);
> +       unsigned long flags;
> +
> +       spin_lock_irqsave(&dev->power.lock, flags);
>         dev->power.no_pm_callbacks =
>                 (!dev->bus || (pm_ops_is_empty(dev->bus->pm) &&
>                  !dev->bus->suspend && !dev->bus->resume)) &&
> @@ -2027,7 +2029,7 @@ void device_pm_check_callbacks(struct device *dev)
>                 (!dev->pm_domain || pm_ops_is_empty(&dev->pm_domain->ops)) &&
>                 (!dev->driver || (pm_ops_is_empty(dev->driver->pm) &&
>                  !dev->driver->suspend && !dev->driver->resume));
> -       spin_unlock_irq(&dev->power.lock);
> +       spin_unlock_irqrestore(&dev->power.lock, flags);
>  }
>
>  bool dev_pm_skip_suspend(struct device *dev)
> --

Applied as 5.18 material, thanks!