On Thu, May 21, 2020 at 5:16 PM Bjorn Helgaas <helgaas@xxxxxxxxxx> wrote:
>
> [+cc Rafael, linux-pm]
>
> On Thu, May 21, 2020 at 11:13:49AM +0800, Dinghao Liu wrote:
> > pm_runtime_get_sync() increments the runtime PM usage counter even
> > when it returns an error code. Thus a pairing decrement is needed on
> > the error handling path to keep the counter balanced.
>
> I didn't realize there were so many drivers with the exact same issue.
> Can we just squash these all into a single patch so we can see them
> all together?
>
> Hmm. There are over 1300 callers of pm_runtime_get_sync(), and it
> looks like many of them have similar issues, i.e., they have a pattern
> like this
>
> ret = pm_runtime_get_sync(dev);
> if (ret < 0)
> return;
>
> pm_runtime_put(dev);
>
> where there is not a pm_runtime_put() to match every
> pm_runtime_get_sync(). Random sample:
>
> nds32_pmu_reserve_hardware
> sata_rcar_probe
> exynos_trng_probe
> ks_sa_rng_probe
> omap_aes_probe
> sun8i_ss_probe
> omap_aes_probe
> zynq_gpio_probe
> amdgpu_hwmon_show_power_avg
> mtk_crtc_ddp_hw_init
> ...
>
> Surely I'm missing something and these aren't all broken, right?
If they do what you've said, they are all broken I'm afraid.
They should all be doing something like
ret = pm_runtime_get_sync(dev);
if (ret < 0)
goto out;
...
out:
pm_runtime_put(dev);
> Maybe we could put together a coccinelle script to scan the tree for
> this issue?
>
> > Signed-off-by: Dinghao Liu <dinghao.liu@xxxxxxxxxx>
> > ---
> > drivers/pci/controller/dwc/pcie-tegra194.c | 5 ++---
> > 1 file changed, 2 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/pci/controller/dwc/pcie-tegra194.c b/drivers/pci/controller/dwc/pcie-tegra194.c
> > index ae30a2fd3716..2c0d2ce16b47 100644
> > --- a/drivers/pci/controller/dwc/pcie-tegra194.c
> > +++ b/drivers/pci/controller/dwc/pcie-tegra194.c
> > @@ -1623,7 +1623,7 @@ static int tegra_pcie_config_rp(struct tegra_pcie_dw *pcie)
> > ret = pinctrl_pm_select_default_state(dev);
> > if (ret < 0) {
> > dev_err(dev, "Failed to configure sideband pins: %d\n", ret);
> > - goto fail_pinctrl;
> > + goto fail_pm_get_sync;
> > }
> >
> > tegra_pcie_init_controller(pcie);
> > @@ -1650,9 +1650,8 @@ static int tegra_pcie_config_rp(struct tegra_pcie_dw *pcie)
> >
> > fail_host_init:
> > tegra_pcie_deinit_controller(pcie);
> > -fail_pinctrl:
> > - pm_runtime_put_sync(dev);
> > fail_pm_get_sync:
> > + pm_runtime_put_sync(dev);
Why not pm_runtime_put()?
> > pm_runtime_disable(dev);
> > return ret;
> > }
> > --
> > 2.17.1
> >
