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

[Roman Demidov]

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...@gmail.com>
---
 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);
        return ret;
 }
 
-- 
2.53.0