Re: [PATCH] drm/meson: switch to a managed drm device

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Hi,

30/08/24 11:29, neil.armstrong@xxxxxxxxxx пишет:
On 30/08/2024 10:23, Anastasia Belova wrote:
Hi,

29/08/24 15:14, Neil Armstrong пишет:
Hi,

On 28/08/2024 13:04, Anastasia Belova wrote:
Switch to a managed drm device to cleanup some error handling
and make future work easier.

Fix dereference of NULL in meson_drv_bind_master by removing
drm_dev_put(drm) before meson_encoder_*_remove where drm
dereferenced.

Please send the fix separately with a Fixes tag.


This fix can't be separated from the patch. drm_dev_put may be
removed only while switching to a managed drm. Otherwise
a check could be added before calling meson_encoder_*_remove.
But it would become redundant after switching to a managed drm.

I may send the second version of this patch with Fixes tag, so all
changes could be applied to older versions.

Reading the currenrt code, component_unbind_all(dev, drm) is called
after drm_dev_put(drm), which is quite wrong aswell.

So perhaps we should keep the kref on drm  until component_unbind_all()
is called in the first case, no ?

Right, but with a managed drm we don't need to release kref ourselves.

The comment for commit is not complete. Information about dereference
of NULL in component_unbind_all may be added in the second version, as
well as Fixes tag.

Anastasia Belova


Neil


Thanks,
Anastasia Belova

Thanks,
Neil


Co-developed by Linux Verification Center (linuxtesting.org).

Signed-off-by: Anastasia Belova <abelova@xxxxxxxxxxxxx>
---
  drivers/gpu/drm/meson/meson_crtc.c         | 10 +--
  drivers/gpu/drm/meson/meson_drv.c          | 71 ++++++++++------------
  drivers/gpu/drm/meson/meson_drv.h          |  2 +-
  drivers/gpu/drm/meson/meson_encoder_cvbs.c |  8 +--
  drivers/gpu/drm/meson/meson_overlay.c      |  8 +--
  drivers/gpu/drm/meson/meson_plane.c        | 10 +--
  6 files changed, 51 insertions(+), 58 deletions(-)

diff --git a/drivers/gpu/drm/meson/meson_crtc.c b/drivers/gpu/drm/meson/meson_crtc.c
index d70616da8ce2..e1c0bf3baeea 100644
--- a/drivers/gpu/drm/meson/meson_crtc.c
+++ b/drivers/gpu/drm/meson/meson_crtc.c
@@ -662,13 +662,13 @@ void meson_crtc_irq(struct meson_drm *priv)
        drm_crtc_handle_vblank(priv->crtc);
  -    spin_lock_irqsave(&priv->drm->event_lock, flags);
+    spin_lock_irqsave(&priv->drm.event_lock, flags);
      if (meson_crtc->event) {
          drm_crtc_send_vblank_event(priv->crtc, meson_crtc->event);
          drm_crtc_vblank_put(priv->crtc);
          meson_crtc->event = NULL;
      }
- spin_unlock_irqrestore(&priv->drm->event_lock, flags);
+    spin_unlock_irqrestore(&priv->drm.event_lock, flags);
  }
    int meson_crtc_create(struct meson_drm *priv)
@@ -677,18 +677,18 @@ int meson_crtc_create(struct meson_drm *priv)
      struct drm_crtc *crtc;
      int ret;
  -    meson_crtc = devm_kzalloc(priv->drm->dev, sizeof(*meson_crtc),
+    meson_crtc = devm_kzalloc(priv->drm.dev, sizeof(*meson_crtc),
                    GFP_KERNEL);
      if (!meson_crtc)
          return -ENOMEM;
        meson_crtc->priv = priv;
      crtc = &meson_crtc->base;
-    ret = drm_crtc_init_with_planes(priv->drm, crtc,
+    ret = drm_crtc_init_with_planes(&priv->drm, crtc,
                      priv->primary_plane, NULL,
                      &meson_crtc_funcs, "meson_crtc");
      if (ret) {
-        dev_err(priv->drm->dev, "Failed to init CRTC\n");
+        dev_err(priv->drm.dev, "Failed to init CRTC\n");
          return ret;
      }
  diff --git a/drivers/gpu/drm/meson/meson_drv.c b/drivers/gpu/drm/meson/meson_drv.c
index 4bd0baa2a4f5..2e7c2e7c7b82 100644
--- a/drivers/gpu/drm/meson/meson_drv.c
+++ b/drivers/gpu/drm/meson/meson_drv.c
@@ -182,7 +182,6 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      struct platform_device *pdev = to_platform_device(dev);
      const struct meson_drm_match_data *match;
      struct meson_drm *priv;
-    struct drm_device *drm;
      struct resource *res;
      void __iomem *regs;
      int ret, i;
@@ -197,17 +196,13 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      if (!match)
          return -ENODEV;
  -    drm = drm_dev_alloc(&meson_driver, dev);
-    if (IS_ERR(drm))
-        return PTR_ERR(drm);
+    priv = devm_drm_dev_alloc(dev, &meson_driver,
+                 struct meson_drm, drm);
  -    priv = devm_kzalloc(dev, sizeof(*priv), GFP_KERNEL);
-    if (!priv) {
-        ret = -ENOMEM;
-        goto free_drm;
-    }
-    drm->dev_private = priv;
-    priv->drm = drm;
+    if (IS_ERR(priv))
+        return PTR_ERR(priv);
+
+    priv->drm.dev_private = priv;
      priv->dev = dev;
      priv->compat = match->compat;
      priv->afbcd.ops = match->afbcd_ops;
@@ -215,7 +210,7 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      regs = devm_platform_ioremap_resource_byname(pdev, "vpu");
      if (IS_ERR(regs)) {
          ret = PTR_ERR(regs);
-        goto free_drm;
+        goto remove_encoders;
      }
        priv->io_base = regs;
@@ -223,13 +218,13 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      res = platform_get_resource_byname(pdev, IORESOURCE_MEM, "hhi");
      if (!res) {
          ret = -EINVAL;
-        goto free_drm;
+        goto remove_encoders;
      }
      /* Simply ioremap since it may be a shared register zone */
      regs = devm_ioremap(dev, res->start, resource_size(res));
      if (!regs) {
          ret = -EADDRNOTAVAIL;
-        goto free_drm;
+        goto remove_encoders;
      }
        priv->hhi = devm_regmap_init_mmio(dev, regs,
@@ -237,18 +232,18 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      if (IS_ERR(priv->hhi)) {
          dev_err(&pdev->dev, "Couldn't create the HHI regmap\n");
          ret = PTR_ERR(priv->hhi);
-        goto free_drm;
+        goto remove_encoders;
      }
        priv->canvas = meson_canvas_get(dev);
      if (IS_ERR(priv->canvas)) {
          ret = PTR_ERR(priv->canvas);
-        goto free_drm;
+        goto remove_encoders;
      }
        ret = meson_canvas_alloc(priv->canvas, &priv->canvas_id_osd1);
      if (ret)
-        goto free_drm;
+        goto remove_encoders;
      ret = meson_canvas_alloc(priv->canvas, &priv->canvas_id_vd1_0);
      if (ret)
          goto free_canvas_osd1;
@@ -261,7 +256,7 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
        priv->vsync_irq = platform_get_irq(pdev, 0);
  -    ret = drm_vblank_init(drm, 1);
+    ret = drm_vblank_init(&priv->drm, 1);
      if (ret)
          goto free_canvas_vd1_2;
  @@ -284,10 +279,10 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      ret = drmm_mode_config_init(drm);
      if (ret)
          goto free_canvas_vd1_2;
-    drm->mode_config.max_width = 3840;
-    drm->mode_config.max_height = 2160;
-    drm->mode_config.funcs = &meson_mode_config_funcs;
-    drm->mode_config.helper_private    = &meson_mode_config_helpers;
+    priv->drm.mode_config.max_width = 3840;
+    priv->drm.mode_config.max_height = 2160;
+    priv->drm.mode_config.funcs = &meson_mode_config_funcs;
+    priv->drm.mode_config.helper_private = &meson_mode_config_helpers;
        /* Hardware Initialization */
  @@ -308,9 +303,9 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
          goto exit_afbcd;
        if (has_components) {
-        ret = component_bind_all(dev, drm);
+        ret = component_bind_all(dev, &priv->drm);
          if (ret) {
-            dev_err(drm->dev, "Couldn't bind all components\n");
+            dev_err(priv->drm.dev, "Couldn't bind all components\n");
              /* Do not try to unbind */
              has_components = false;
              goto exit_afbcd;
@@ -339,26 +334,26 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      if (ret)
          goto exit_afbcd;
  -    ret = request_irq(priv->vsync_irq, meson_irq, 0, drm->driver->name, drm); +    ret = request_irq(priv->vsync_irq, meson_irq, 0, priv->drm.driver->name, &priv->drm);
      if (ret)
          goto exit_afbcd;
  -    drm_mode_config_reset(drm);
+    drm_mode_config_reset(&priv->drm);
  -    drm_kms_helper_poll_init(drm);
+    drm_kms_helper_poll_init(&priv->drm);
        platform_set_drvdata(pdev, priv);
  -    ret = drm_dev_register(drm, 0);
+    ret = drm_dev_register(&priv->drm, 0);
      if (ret)
          goto uninstall_irq;
  -    drm_fbdev_dma_setup(drm, 32);
+    drm_fbdev_dma_setup(&priv->drm, 32);
        return 0;
    uninstall_irq:
-    free_irq(priv->vsync_irq, drm);
+    free_irq(priv->vsync_irq, &priv->drm);
  exit_afbcd:
      if (priv->afbcd.ops)
          priv->afbcd.ops->exit(priv);
@@ -370,15 +365,14 @@ static int meson_drv_bind_master(struct device *dev, bool has_components)
      meson_canvas_free(priv->canvas, priv->canvas_id_vd1_0);
  free_canvas_osd1:
      meson_canvas_free(priv->canvas, priv->canvas_id_osd1);
-free_drm:
-    drm_dev_put(drm);
+remove_encoders:
        meson_encoder_dsi_remove(priv);
      meson_encoder_hdmi_remove(priv);
      meson_encoder_cvbs_remove(priv);
        if (has_components)
-        component_unbind_all(dev, drm);
+        component_unbind_all(dev, &priv->drm);
        return ret;
  }
@@ -391,7 +385,7 @@ static int meson_drv_bind(struct device *dev)
  static void meson_drv_unbind(struct device *dev)
  {
      struct meson_drm *priv = dev_get_drvdata(dev);
-    struct drm_device *drm = priv->drm;
+    struct drm_device *drm = &priv->drm;
        if (priv->canvas) {
          meson_canvas_free(priv->canvas, priv->canvas_id_osd1);
@@ -404,7 +398,6 @@ static void meson_drv_unbind(struct device *dev)
      drm_kms_helper_poll_fini(drm);
      drm_atomic_helper_shutdown(drm);
      free_irq(priv->vsync_irq, drm);
-    drm_dev_put(drm);
        meson_encoder_dsi_remove(priv);
      meson_encoder_hdmi_remove(priv);
@@ -428,7 +421,7 @@ static int __maybe_unused meson_drv_pm_suspend(struct device *dev)
      if (!priv)
          return 0;
  -    return drm_mode_config_helper_suspend(priv->drm);
+    return drm_mode_config_helper_suspend(&priv->drm);
  }
    static int __maybe_unused meson_drv_pm_resume(struct device *dev)
@@ -445,7 +438,7 @@ static int __maybe_unused meson_drv_pm_resume(struct device *dev)
      if (priv->afbcd.ops)
          priv->afbcd.ops->init(priv);
  -    return drm_mode_config_helper_resume(priv->drm);
+    return drm_mode_config_helper_resume(&priv->drm);
  }
    static void meson_drv_shutdown(struct platform_device *pdev)
@@ -455,8 +448,8 @@ static void meson_drv_shutdown(struct platform_device *pdev)
      if (!priv)
          return;
  -    drm_kms_helper_poll_fini(priv->drm);
-    drm_atomic_helper_shutdown(priv->drm);
+    drm_kms_helper_poll_fini(&priv->drm);
+    drm_atomic_helper_shutdown(&priv->drm);
  }
    /*
diff --git a/drivers/gpu/drm/meson/meson_drv.h b/drivers/gpu/drm/meson/meson_drv.h
index 3f9345c14f31..c4c6c810cb20 100644
--- a/drivers/gpu/drm/meson/meson_drv.h
+++ b/drivers/gpu/drm/meson/meson_drv.h
@@ -53,7 +53,7 @@ struct meson_drm {
      u8 canvas_id_vd1_1;
      u8 canvas_id_vd1_2;
  -    struct drm_device *drm;
+    struct drm_device drm;
      struct drm_crtc *crtc;
      struct drm_plane *primary_plane;
      struct drm_plane *overlay_plane;
diff --git a/drivers/gpu/drm/meson/meson_encoder_cvbs.c b/drivers/gpu/drm/meson/meson_encoder_cvbs.c
index d1191de855d9..ddca22c8c1ff 100644
--- a/drivers/gpu/drm/meson/meson_encoder_cvbs.c
+++ b/drivers/gpu/drm/meson/meson_encoder_cvbs.c
@@ -104,7 +104,7 @@ static int meson_encoder_cvbs_get_modes(struct drm_bridge *bridge,
      for (i = 0; i < MESON_CVBS_MODES_COUNT; ++i) {
          struct meson_cvbs_mode *meson_mode = &meson_cvbs_modes[i];
  -        mode = drm_mode_duplicate(priv->drm, &meson_mode->mode);
+        mode = drm_mode_duplicate(&priv->drm, &meson_mode->mode);
          if (!mode) {
              dev_err(priv->dev, "Failed to create a new display mode\n");
              return 0;
@@ -221,7 +221,7 @@ static const struct drm_bridge_funcs meson_encoder_cvbs_bridge_funcs = {
    int meson_encoder_cvbs_probe(struct meson_drm *priv)
  {
-    struct drm_device *drm = priv->drm;
+    struct drm_device *drm = &priv->drm;
      struct meson_encoder_cvbs *meson_encoder_cvbs;
      struct drm_connector *connector;
      struct device_node *remote;
@@ -256,7 +256,7 @@ int meson_encoder_cvbs_probe(struct meson_drm *priv)
      meson_encoder_cvbs->priv = priv;
        /* Encoder */
-    ret = drm_simple_encoder_init(priv->drm, &meson_encoder_cvbs->encoder, +    ret = drm_simple_encoder_init(&priv->drm, &meson_encoder_cvbs->encoder,
                        DRM_MODE_ENCODER_TVDAC);
      if (ret)
          return dev_err_probe(priv->dev, ret,
@@ -273,7 +273,7 @@ int meson_encoder_cvbs_probe(struct meson_drm *priv)
      }
        /* Initialize & attach Bridge Connector */
-    connector = drm_bridge_connector_init(priv->drm, &meson_encoder_cvbs->encoder); +    connector = drm_bridge_connector_init(&priv->drm, &meson_encoder_cvbs->encoder);
      if (IS_ERR(connector))
          return dev_err_probe(priv->dev, PTR_ERR(connector),
                       "Unable to create CVBS bridge connector\n");
diff --git a/drivers/gpu/drm/meson/meson_overlay.c b/drivers/gpu/drm/meson/meson_overlay.c
index 7f98de38842b..60ee7f758723 100644
--- a/drivers/gpu/drm/meson/meson_overlay.c
+++ b/drivers/gpu/drm/meson/meson_overlay.c
@@ -484,7 +484,7 @@ static void meson_overlay_atomic_update(struct drm_plane *plane,         interlace_mode = new_state->crtc->mode.flags & DRM_MODE_FLAG_INTERLACE;
  -    spin_lock_irqsave(&priv->drm->event_lock, flags);
+    spin_lock_irqsave(&priv->drm.event_lock, flags);
        if ((fb->modifier & DRM_FORMAT_MOD_AMLOGIC_FBC(0, 0)) ==
                  DRM_FORMAT_MOD_AMLOGIC_FBC(0, 0)) {
@@ -717,7 +717,7 @@ static void meson_overlay_atomic_update(struct drm_plane *plane,
        priv->viu.vd1_enabled = true;
  - spin_unlock_irqrestore(&priv->drm->event_lock, flags);
+    spin_unlock_irqrestore(&priv->drm.event_lock, flags);
        DRM_DEBUG_DRIVER("\n");
  }
@@ -838,7 +838,7 @@ int meson_overlay_create(struct meson_drm *priv)
        DRM_DEBUG_DRIVER("\n");
  -    meson_overlay = devm_kzalloc(priv->drm->dev, sizeof(*meson_overlay), +    meson_overlay = devm_kzalloc(priv->drm.dev, sizeof(*meson_overlay),
                     GFP_KERNEL);
      if (!meson_overlay)
          return -ENOMEM;
@@ -846,7 +846,7 @@ int meson_overlay_create(struct meson_drm *priv)
      meson_overlay->priv = priv;
      plane = &meson_overlay->base;
  -    drm_universal_plane_init(priv->drm, plane, 0xFF,
+    drm_universal_plane_init(&priv->drm, plane, 0xFF,
                   &meson_overlay_funcs,
                   supported_drm_formats,
                   ARRAY_SIZE(supported_drm_formats),
diff --git a/drivers/gpu/drm/meson/meson_plane.c b/drivers/gpu/drm/meson/meson_plane.c
index b43ac61201f3..13be94309bf4 100644
--- a/drivers/gpu/drm/meson/meson_plane.c
+++ b/drivers/gpu/drm/meson/meson_plane.c
@@ -157,7 +157,7 @@ static void meson_plane_atomic_update(struct drm_plane *plane,
       * Update Buffer
       * Enable Plane
       */
-    spin_lock_irqsave(&priv->drm->event_lock, flags);
+    spin_lock_irqsave(&priv->drm.event_lock, flags);
        /* Check if AFBC decoder is required for this buffer */
      if ((meson_vpu_is_compatible(priv, VPU_COMPATIBLE_GXM) ||
@@ -393,7 +393,7 @@ static void meson_plane_atomic_update(struct drm_plane *plane,
        priv->viu.osd1_enabled = true;
  - spin_unlock_irqrestore(&priv->drm->event_lock, flags);
+    spin_unlock_irqrestore(&priv->drm.event_lock, flags);
  }
    static void meson_plane_atomic_disable(struct drm_plane *plane,
@@ -536,7 +536,7 @@ int meson_plane_create(struct meson_drm *priv)
      const uint64_t *format_modifiers = format_modifiers_default;
      int ret;
  -    meson_plane = devm_kzalloc(priv->drm->dev, sizeof(*meson_plane),
+    meson_plane = devm_kzalloc(priv->drm.dev, sizeof(*meson_plane),
                     GFP_KERNEL);
      if (!meson_plane)
          return -ENOMEM;
@@ -549,14 +549,14 @@ int meson_plane_create(struct meson_drm *priv)
      else if (meson_vpu_is_compatible(priv, VPU_COMPATIBLE_G12A))
          format_modifiers = format_modifiers_afbc_g12a;
  -    ret = drm_universal_plane_init(priv->drm, plane, 0xFF,
+    ret = drm_universal_plane_init(&priv->drm, plane, 0xFF,
                      &meson_plane_funcs,
                      supported_drm_formats,
                      ARRAY_SIZE(supported_drm_formats),
                      format_modifiers,
                      DRM_PLANE_TYPE_PRIMARY, "meson_primary_plane");
      if (ret) {
-        devm_kfree(priv->drm->dev, meson_plane);
+        devm_kfree(priv->drm.dev, meson_plane);
          return ret;
      }







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