Some DRM resources such as plane, CRTC or encoder objects could remain in
use after the DRM device is removed. Use the drm_dev_enter/exit() mechanism
to ensure that the DRM device is not unplugged before using its resources.

Fixes: efeeaefe9be56 ("drm: Add support for the LogiCVC display controller")    
                                                                    │
Cc: [email protected]
Signed-off-by: Romain Gantois <[email protected]>
---
 drivers/gpu/drm/logicvc/logicvc_crtc.c      | 39 +++++++++++++++++++++++++++++
 drivers/gpu/drm/logicvc/logicvc_drm.c       |  6 ++++-
 drivers/gpu/drm/logicvc/logicvc_interface.c | 12 +++++++++
 drivers/gpu/drm/logicvc/logicvc_layer.c     | 28 ++++++++++++++++-----
 4 files changed, 78 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/logicvc/logicvc_crtc.c 
b/drivers/gpu/drm/logicvc/logicvc_crtc.c
index 3a4c347eaa648..e2575fa78ab25 100644
--- a/drivers/gpu/drm/logicvc/logicvc_crtc.c
+++ b/drivers/gpu/drm/logicvc/logicvc_crtc.c
@@ -36,6 +36,21 @@ logicvc_crtc_mode_valid(struct drm_crtc *drm_crtc,
        return 0;
 }
 
+static void logicvc_crtc_drop_any_event(struct drm_device *drm_dev,
+                                       struct drm_crtc *drm_crtc)
+{
+       unsigned long flags;
+
+       spin_lock_irqsave(&drm_dev->event_lock, flags);
+
+       if (drm_crtc->state->event) {
+               drm_crtc->state->event = NULL;
+               drm_warn(drm_crtc->dev, "Device is unplugged, ignoring pending 
vblank event!");
+       }
+
+       spin_unlock_irqrestore(&drm_dev->event_lock, flags);
+}
+
 static void logicvc_crtc_atomic_begin(struct drm_crtc *drm_crtc,
                                      struct drm_atomic_state *state)
 {
@@ -44,6 +59,12 @@ static void logicvc_crtc_atomic_begin(struct drm_crtc 
*drm_crtc,
                drm_atomic_get_old_crtc_state(state, drm_crtc);
        struct drm_device *drm_dev = drm_crtc->dev;
        unsigned long flags;
+       int idx;
+
+       if (!drm_dev_enter(drm_dev, &idx)) {
+               logicvc_crtc_drop_any_event(drm_dev, drm_crtc);
+               return;
+       }
 
        /*
         * We need to grab the pending event here if vblank was already enabled
@@ -58,6 +79,8 @@ static void logicvc_crtc_atomic_begin(struct drm_crtc 
*drm_crtc,
 
                spin_unlock_irqrestore(&drm_dev->event_lock, flags);
        }
+
+       drm_dev_exit(idx);
 }
 
 static void logicvc_crtc_atomic_enable(struct drm_crtc *drm_crtc,
@@ -76,6 +99,12 @@ static void logicvc_crtc_atomic_enable(struct drm_crtc 
*drm_crtc,
        unsigned int vact, vfp, vsl, vbp;
        unsigned long flags;
        u32 ctrl;
+       int idx;
+
+       if (!drm_dev_enter(drm_dev, &idx)) {
+               logicvc_crtc_drop_any_event(drm_dev, drm_crtc);
+               return;
+       }
 
        /* Timings */
 
@@ -148,6 +177,8 @@ static void logicvc_crtc_atomic_enable(struct drm_crtc 
*drm_crtc,
                drm_crtc->state->event = NULL;
                spin_unlock_irqrestore(&drm_dev->event_lock, flags);
        }
+
+       drm_dev_exit(idx);
 }
 
 static void logicvc_crtc_atomic_disable(struct drm_crtc *drm_crtc,
@@ -155,6 +186,12 @@ static void logicvc_crtc_atomic_disable(struct drm_crtc 
*drm_crtc,
 {
        struct logicvc_drm *logicvc = logicvc_drm(drm_crtc->dev);
        struct drm_device *drm_dev = drm_crtc->dev;
+       int idx;
+
+       if (!drm_dev_enter(drm_dev, &idx)) {
+               logicvc_crtc_drop_any_event(drm_dev, drm_crtc);
+               return;
+       }
 
        drm_crtc_vblank_off(drm_crtc);
 
@@ -180,6 +217,8 @@ static void logicvc_crtc_atomic_disable(struct drm_crtc 
*drm_crtc,
                drm_crtc->state->event = NULL;
                spin_unlock_irq(&drm_dev->event_lock);
        }
+
+       drm_dev_exit(idx);
 }
 
 static const struct drm_crtc_helper_funcs logicvc_crtc_helper_funcs = {
diff --git a/drivers/gpu/drm/logicvc/logicvc_drm.c 
b/drivers/gpu/drm/logicvc/logicvc_drm.c
index bbebf4fc7f51a..fb66f5fb67937 100644
--- a/drivers/gpu/drm/logicvc/logicvc_drm.c
+++ b/drivers/gpu/drm/logicvc/logicvc_drm.c
@@ -72,6 +72,10 @@ static irqreturn_t logicvc_drm_irq_handler(int irq, void 
*data)
        irqreturn_t ret = IRQ_NONE;
        u32 stat = 0;
 
+       /* The interrupt handler will be unregistered when the device is
+        * removed. Therefore, there's no need for drm_dev_enter() here.
+        */
+
        /* Get pending interrupt sources. */
        regmap_read(logicvc->regmap, LOGICVC_INT_STAT_REG, &stat);
 
@@ -463,7 +467,7 @@ static void logicvc_drm_remove(struct platform_device *pdev)
        struct device *dev = &pdev->dev;
        struct drm_device *drm_dev = &logicvc->drm_dev;
 
-       drm_dev_unregister(drm_dev);
+       drm_dev_unplug(drm_dev);
        drm_atomic_helper_shutdown(drm_dev);
 
        logicvc_mode_fini(logicvc);
diff --git a/drivers/gpu/drm/logicvc/logicvc_interface.c 
b/drivers/gpu/drm/logicvc/logicvc_interface.c
index 0d037f37b950f..aa13338a29535 100644
--- a/drivers/gpu/drm/logicvc/logicvc_interface.c
+++ b/drivers/gpu/drm/logicvc/logicvc_interface.c
@@ -34,6 +34,10 @@ static void logicvc_encoder_enable(struct drm_encoder 
*drm_encoder)
        struct logicvc_drm *logicvc = logicvc_drm(drm_encoder->dev);
        struct logicvc_interface *interface =
                logicvc_interface_from_drm_encoder(drm_encoder);
+       int idx;
+
+       if (!drm_dev_enter(drm_encoder->dev, &idx))
+               return;
 
        regmap_update_bits(logicvc->regmap, LOGICVC_POWER_CTRL_REG,
                           LOGICVC_POWER_CTRL_VIDEO_ENABLE,
@@ -43,17 +47,25 @@ static void logicvc_encoder_enable(struct drm_encoder 
*drm_encoder)
                drm_panel_prepare(interface->drm_panel);
                drm_panel_enable(interface->drm_panel);
        }
+
+       drm_dev_exit(idx);
 }
 
 static void logicvc_encoder_disable(struct drm_encoder *drm_encoder)
 {
        struct logicvc_interface *interface =
                logicvc_interface_from_drm_encoder(drm_encoder);
+       int idx;
+
+       if (!drm_dev_enter(drm_encoder->dev, &idx))
+               return;
 
        if (interface->drm_panel) {
                drm_panel_disable(interface->drm_panel);
                drm_panel_unprepare(interface->drm_panel);
        }
+
+       drm_dev_exit(idx);
 }
 
 static const struct drm_encoder_helper_funcs logicvc_encoder_helper_funcs = {
diff --git a/drivers/gpu/drm/logicvc/logicvc_layer.c 
b/drivers/gpu/drm/logicvc/logicvc_layer.c
index de1f4a8a61557..4d9bfd57affcf 100644
--- a/drivers/gpu/drm/logicvc/logicvc_layer.c
+++ b/drivers/gpu/drm/logicvc/logicvc_layer.c
@@ -10,6 +10,7 @@
 #include <drm/drm_atomic.h>
 #include <drm/drm_atomic_helper.h>
 #include <drm/drm_blend.h>
+#include <drm/drm_drv.h>
 #include <drm/drm_fb_dma_helper.h>
 #include <drm/drm_fourcc.h>
 #include <drm/drm_framebuffer.h>
@@ -92,7 +93,7 @@ static int logicvc_plane_atomic_check(struct drm_plane 
*drm_plane,
        struct drm_crtc_state *crtc_state;
        int min_scale, max_scale;
        bool can_position;
-       int ret;
+       int idx, ret = 0;
 
        if (!new_state->crtc)
                return 0;
@@ -108,12 +109,15 @@ static int logicvc_plane_atomic_check(struct drm_plane 
*drm_plane,
                return -EINVAL;
        }
 
+       if (!drm_dev_enter(drm_dev, &idx))
+               return -ENODEV;
+
        if (!logicvc->caps->layer_address) {
                ret = logicvc_layer_buffer_find_setup(logicvc, layer, new_state,
                                                      NULL);
                if (ret) {
                        drm_err(drm_dev, "No viable setup for buffer found.\n");
-                       return ret;
+                       goto out_exit;
                }
        }
 
@@ -127,12 +131,12 @@ static int logicvc_plane_atomic_check(struct drm_plane 
*drm_plane,
        ret = drm_atomic_helper_check_plane_state(new_state, crtc_state,
                                                  min_scale, max_scale,
                                                  can_position, true);
-       if (ret) {
+       if (ret)
                drm_err(drm_dev, "Invalid plane state\n\n");
-               return ret;
-       }
 
-       return 0;
+out_exit:
+       drm_dev_exit(idx);
+       return ret;
 }
 
 static void logicvc_plane_atomic_update(struct drm_plane *drm_plane,
@@ -148,8 +152,12 @@ static void logicvc_plane_atomic_update(struct drm_plane 
*drm_plane,
        struct drm_framebuffer *fb = new_state->fb;
        struct logicvc_layer_buffer_setup setup = {};
        u32 index = layer->index;
+       int idx;
        u32 reg;
 
+       if (!drm_dev_enter(drm_dev, &idx))
+               return;
+
        /* Layer dimensions */
 
        regmap_write(logicvc->regmap, LOGICVC_LAYER_WIDTH_REG(index),
@@ -230,6 +238,8 @@ static void logicvc_plane_atomic_update(struct drm_plane 
*drm_plane,
        reg |= LOGICVC_LAYER_CTRL_COLOR_KEY_DISABLE;
 
        regmap_write(logicvc->regmap, LOGICVC_LAYER_CTRL_REG(index), reg);
+
+       drm_dev_exit(idx);
 }
 
 static void logicvc_plane_atomic_disable(struct drm_plane *drm_plane,
@@ -238,8 +248,14 @@ static void logicvc_plane_atomic_disable(struct drm_plane 
*drm_plane,
        struct logicvc_layer *layer = logicvc_layer(drm_plane);
        struct logicvc_drm *logicvc = logicvc_drm(drm_plane->dev);
        u32 index = layer->index;
+       int idx;
+
+       if (!drm_dev_enter(&logicvc->drm_dev, &idx))
+               return;
 
        regmap_write(logicvc->regmap, LOGICVC_LAYER_CTRL_REG(index), 0);
+
+       drm_dev_exit(idx);
 }
 
 static struct drm_plane_helper_funcs logicvc_plane_helper_funcs = {

-- 
2.55.0

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