drm/rockchip: Convert psr_list_mutex to spinlock and use it

This patch converts the psr_list_mutex to a spinlock and locks
all access to psr_list to avoid races (however unlikely they
were).

Reviewed-by: Yakir Yang <ykk@rock-chips.com>
Signed-off-by: Sean Paul <seanpaul@chromium.org>

3 files changed, 20 insertions, 9 deletions

diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
index b43fe5d93828..76eaf1de52e4 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.c
@@ -157,7 +157,7 @@ static int rockchip_drm_bind(struct device *dev)
         drm_dev->dev_private = private;
 
         INIT_LIST_HEAD(&private->psr_list);
-        mutex_init(&private->psr_list_mutex);
+        spin_lock_init(&private->psr_list_lock);
 
         drm_mode_config_init(drm_dev);
 
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
index 9c34c9e181d0..5c698456aa1c 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_drv.h
@@ -63,7 +63,7 @@ struct rockchip_drm_private {
         struct drm_atomic_state *state;
 
         struct list_head psr_list;
-        struct mutex psr_list_mutex;
+        spinlock_t psr_list_lock;
 };
 
 int rockchip_register_crtc_funcs(struct drm_crtc *crtc,
diff --git a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
index a6d3bd25b905..bd25273a89bb 100644
--- a/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
+++ b/drivers/gpu/drm/rockchip/rockchip_drm_psr.c
@@ -45,12 +45,18 @@ static struct psr_drv *find_psr_by_crtc(struct drm_crtc *crtc)
 {
         struct rockchip_drm_private *drm_drv = crtc->dev->dev_private;
         struct psr_drv *psr;
+        unsigned long flags;
 
-        list_for_each_entry(psr, &drm_drv->psr_list, list)
+        spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
+        list_for_each_entry(psr, &drm_drv->psr_list, list) {
                 if (psr->encoder->crtc == crtc)
-                        return psr;
+                        goto out;
+        }
+        psr = ERR_PTR(-ENODEV);
 
-        return ERR_PTR(-ENODEV);
+out:
+        spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
+        return psr;
 }
 
 static void psr_state_work(struct work_struct *work)
@@ -173,7 +179,9 @@ void rockchip_drm_psr_flush(struct drm_device *dev)
 {
         struct rockchip_drm_private *drm_drv = dev->dev_private;
         struct psr_drv *psr;
+        unsigned long flags;
 
+        spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
         list_for_each_entry(psr, &drm_drv->psr_list, list) {
                 if (psr->request_state == PSR_DISABLE)
                         continue;
@@ -183,6 +191,7 @@ void rockchip_drm_psr_flush(struct drm_device *dev)
 
                 psr_set_state(psr, PSR_FLUSH);
         }
+        spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
 }
 EXPORT_SYMBOL(rockchip_drm_psr_flush);
 
@@ -199,6 +208,7 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
 {
         struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
         struct psr_drv *psr;
+        unsigned long flags;
 
         if (!encoder || !psr_set)
                 return -EINVAL;
@@ -215,9 +225,9 @@ int rockchip_drm_psr_register(struct drm_encoder *encoder,
         psr->encoder = encoder;
         psr->set = psr_set;
 
-        mutex_lock(&drm_drv->psr_list_mutex);
+        spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
         list_add_tail(&psr->list, &drm_drv->psr_list);
-        mutex_unlock(&drm_drv->psr_list_mutex);
+        spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
 
         return 0;
 }
@@ -235,8 +245,9 @@ void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
 {
         struct rockchip_drm_private *drm_drv = encoder->dev->dev_private;
         struct psr_drv *psr, *n;
+        unsigned long flags;
 
-        mutex_lock(&drm_drv->psr_list_mutex);
+        spin_lock_irqsave(&drm_drv->psr_list_lock, flags);
         list_for_each_entry_safe(psr, n, &drm_drv->psr_list, list) {
                 if (psr->encoder == encoder) {
                         del_timer(&psr->flush_timer);
@@ -244,6 +255,6 @@ void rockchip_drm_psr_unregister(struct drm_encoder *encoder)
                         kfree(psr);
                 }
         }
-        mutex_unlock(&drm_drv->psr_list_mutex);
+        spin_unlock_irqrestore(&drm_drv->psr_list_lock, flags);
 }
 EXPORT_SYMBOL(rockchip_drm_psr_unregister);