Re: [PATCH] drm/msm/gpu: Fix crash on devices without devfreq support

[Dmitry Baryshkov]

On 19/02/2022 21:33, Rob Clark wrote:
From: Rob Clark <robdcl...@chromium.org>
Avoid going down devfreq paths on devices where devfreq is not
initialized.

Reported-by: Linux Kernel Functional Testing <l...@linaro.org>
Reported-by: Anders Roxell <anders.rox...@linaro.org>
Signed-off-by: Rob Clark <robdcl...@chromium.org>
---
  drivers/gpu/drm/msm/msm_gpu_devfreq.c | 31 +++++++++++++++++++++------
  1 file changed, 25 insertions(+), 6 deletions(-)

diff --git a/drivers/gpu/drm/msm/msm_gpu_devfreq.c 
b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
index 9bf319be11f6..26a3669a97b3 100644
--- a/drivers/gpu/drm/msm/msm_gpu_devfreq.c
+++ b/drivers/gpu/drm/msm/msm_gpu_devfreq.c
@@ -83,12 +83,17 @@ static struct devfreq_dev_profile msm_devfreq_profile = {
  static void msm_devfreq_boost_work(struct kthread_work *work);
  static void msm_devfreq_idle_work(struct kthread_work *work);
  
+static bool has_devfreq(struct msm_gpu *gpu)
+{
+       return !!gpu->funcs->gpu_busy;

I see that devfreq init will be skipped if gpu_busy is NULL.
Can we use gpu->devfreq instead of this condition?

I noticed that you have replaced some of gpu->devfreq checks with 
has_devreq() calls. Is there any difference?

+}
+
  void msm_devfreq_init(struct msm_gpu *gpu)
  {
        struct msm_gpu_devfreq *df = &gpu->devfreq;
  
  	/* We need target support to do devfreq */
-       if (!gpu->funcs->gpu_busy)
+       if (!has_devfreq(gpu))
                return;
  
  	dev_pm_qos_add_request(&gpu->pdev->dev, &df->idle_freq,
@@ -149,6 +154,9 @@ void msm_devfreq_cleanup(struct msm_gpu *gpu)
  {
        struct msm_gpu_devfreq *df = &gpu->devfreq;
  
+	if (!has_devfreq(gpu))
+               return;
+
        devfreq_cooling_unregister(gpu->cooling);
        dev_pm_qos_remove_request(&df->boost_freq);
        dev_pm_qos_remove_request(&df->idle_freq);
@@ -156,16 +164,24 @@ void msm_devfreq_cleanup(struct msm_gpu *gpu)
  
  void msm_devfreq_resume(struct msm_gpu *gpu)
  {
-       gpu->devfreq.busy_cycles = 0;
-       gpu->devfreq.time = ktime_get();
+       struct msm_gpu_devfreq *df = &gpu->devfreq;
  
-	devfreq_resume_device(gpu->devfreq.devfreq);
+       if (!has_devfreq(gpu))
+               return;
+
+       df->busy_cycles = 0;
+       df->time = ktime_get();
+
+       devfreq_resume_device(df->devfreq);
  }
  
  void msm_devfreq_suspend(struct msm_gpu *gpu)
  {
        struct msm_gpu_devfreq *df = &gpu->devfreq;
  
+	if (!has_devfreq(gpu))
+               return;
+
        devfreq_suspend_device(df->devfreq);
  
  	cancel_idle_work(df);
@@ -185,6 +201,9 @@ void msm_devfreq_boost(struct msm_gpu *gpu, unsigned factor)
        struct msm_gpu_devfreq *df = &gpu->devfreq;
        uint64_t freq;
  
+	if (!has_devfreq(gpu))
+               return;
+
        freq = get_freq(gpu);
        freq *= factor;
  
@@ -207,7 +226,7 @@ void msm_devfreq_active(struct msm_gpu *gpu)
        struct devfreq_dev_status status;
        unsigned int idle_time;
  
-	if (!df->devfreq)
+       if (!has_devfreq(gpu))
                return;
  
  	/*
@@ -253,7 +272,7 @@ void msm_devfreq_idle(struct msm_gpu *gpu)
  {
        struct msm_gpu_devfreq *df = &gpu->devfreq;
  
-	if (!df->devfreq)
+       if (!has_devfreq(gpu))
                return;
  
  	msm_hrtimer_queue_work(&df->idle_work, ms_to_ktime(1),


--
With best wishes
Dmitry