Re: [PATCH] drm/msm/a6xx: check pm_runtime_resume_and_get() during resume

[Rob Clark]

On Fri, Sep 4, 2026 at 5:58 AM Roman Demidov <roman.demidov.nn@xxxxxxxxx> wrote:
>
> The return values of pm_runtime_resume_and_get() calls in a6xx_pm_resume()
> are not checked, which can lead to hardware access on suspended devices
> and PM reference underflows.
>
> Fix this by checking the return value of each pm_runtime_resume_and_get()
> call and properly unwinding the previously acquired resources on failure.
>
> Found by Linux Verification Center (linuxtesting.org) with SVACE.
>
> Fixes: 5a903a44a984 ("drm/msm/a6xx: Introduce GMU wrapper support")
> Signed-off-by: Roman Demidov <roman.demidov.nn@xxxxxxxxx>
> ---
>  drivers/gpu/drm/msm/adreno/a6xx_gpu.c | 38 +++++++++++++++------------
>  1 file changed, 21 insertions(+), 17 deletions(-)
>
> diff --git a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> index f9de9329dee3..0cf205ea744b 100644
> --- a/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> +++ b/drivers/gpu/drm/msm/adreno/a6xx_gpu.c
> @@ -2175,44 +2175,48 @@ static int a6xx_pm_resume(struct msm_gpu *gpu)
>         opp = dev_pm_opp_find_freq_ceil(&gpu->pdev->dev, &freq);
>         if (IS_ERR(opp)) {
>                 ret = PTR_ERR(opp);
> -               goto err_set_opp;
> +               goto err_unlock;
>         }
>         dev_pm_opp_put(opp);
>
>         /* Set the core clock and bus bw, having VDD scaling in mind */
>         dev_pm_opp_set_opp(&gpu->pdev->dev, opp);
>
> -       pm_runtime_resume_and_get(gmu->dev);
> -       pm_runtime_resume_and_get(gmu->gxpd);
> +       ret = pm_runtime_resume_and_get(gmu->dev);
> +       if (ret < 0)
> +               goto err_opp_clear;
> +       ret = pm_runtime_resume_and_get(gmu->gxpd);
> +       if (ret < 0)
> +               goto err_put_dev;
>
>         ret = clk_bulk_prepare_enable(gpu->nr_clocks, gpu->grp_clks);
>         if (ret)
> -               goto err_bulk_clk;
> +               goto err_put_gxpd;
>
>         ret = clk_bulk_prepare_enable(gmu->nr_clocks, gmu->clocks);
>         if (ret) {
>                 clk_bulk_disable_unprepare(gpu->nr_clocks, gpu->grp_clks);
> -               goto err_bulk_clk;
> +               goto err_put_gxpd;
>         }
>
>         if (adreno_is_a619_holi(adreno_gpu))
>                 a6xx_sptprac_enable(gmu);
>
> -       /* If anything goes south, tear the GPU down piece by piece.. */
> -       if (ret) {
> -err_bulk_clk:
> -               pm_runtime_put(gmu->gxpd);
> -               pm_runtime_put(gmu->dev);
> -               dev_pm_opp_set_opp(&gpu->pdev->dev, NULL);
> -       }
> -err_set_opp:
>         mutex_unlock(&a6xx_gpu->gmu.lock);
> +       msm_devfreq_resume(gpu);
> +       a6xx_llc_activate(a6xx_gpu);
>
> -       if (!ret) {
> -               msm_devfreq_resume(gpu);
> -               a6xx_llc_activate(a6xx_gpu);
> -       }
> +       return 0;
>
> +       /* If anything goes south, tear the GPU down piece by piece.. */
> +err_put_gxpd:
> +       pm_runtime_put(gmu->gxpd);
> +err_put_dev:
> +       pm_runtime_put(gmu->dev);
> +err_opp_clear:
> +       dev_pm_opp_set_opp(&gpu->pdev->dev, NULL);
> +err_unlock:
> +       mutex_unlock(&a6xx_gpu->gmu.lock);

this does at least look a bit less terrifying than what came before...
but maybe

   guard(mutex)(&a6xx_gpu->gmu.lock);

to simplify the locking part of this.  And I think at least some of
the runpm stuff could also be handled w/ guard/cleanup stuff?

BR,
-R

>         return ret;
>  }
>
> --
> 2.53.0
>