[PATCH] v4l: vsp1: Don't sleep in atomic context

[Laurent Pinchart]

The vsp1_entity_is_streaming() function is called in atomic context when
queuing buffers, and sleeps due to a mutex. As the mutex just protects
access to one structure field, fix this by replace the mutex with a
spinlock.

Signed-off-by: Laurent Pinchart <laurent.pinchart+rene...@ideasonboard.com>
---
 drivers/media/platform/vsp1/vsp1_entity.c | 18 +++++++++---------
 drivers/media/platform/vsp1/vsp1_entity.h |  4 ++--
 2 files changed, 11 insertions(+), 11 deletions(-)

This bug seems to have been there since the very first version of the VSP1
driver and never got caught. Amazing...

diff --git a/drivers/media/platform/vsp1/vsp1_entity.c 
b/drivers/media/platform/vsp1/vsp1_entity.c
index 79af71d5e270..622acd1c8d58 100644
--- a/drivers/media/platform/vsp1/vsp1_entity.c
+++ b/drivers/media/platform/vsp1/vsp1_entity.c
@@ -24,22 +24,24 @@
 
 bool vsp1_entity_is_streaming(struct vsp1_entity *entity)
 {
+       unsigned long flags;
        bool streaming;
 
-       mutex_lock(&entity->lock);
+       spin_lock_irqsave(&entity->lock, flags);
        streaming = entity->streaming;
-       mutex_unlock(&entity->lock);
+       spin_unlock_irqrestore(&entity->lock, flags);
 
        return streaming;
 }
 
 int vsp1_entity_set_streaming(struct vsp1_entity *entity, bool streaming)
 {
+       unsigned long flags;
        int ret;
 
-       mutex_lock(&entity->lock);
+       spin_lock_irqsave(&entity->lock, flags);
        entity->streaming = streaming;
-       mutex_unlock(&entity->lock);
+       spin_unlock_irqrestore(&entity->lock, flags);
 
        if (!streaming)
                return 0;
@@ -49,9 +51,9 @@ int vsp1_entity_set_streaming(struct vsp1_entity *entity, 
bool streaming)
 
        ret = v4l2_ctrl_handler_setup(entity->subdev.ctrl_handler);
        if (ret < 0) {
-               mutex_lock(&entity->lock);
+               spin_lock_irqsave(&entity->lock, flags);
                entity->streaming = false;
-               mutex_unlock(&entity->lock);
+               spin_unlock_irqrestore(&entity->lock, flags);
        }
 
        return ret;
@@ -193,7 +195,7 @@ int vsp1_entity_init(struct vsp1_device *vsp1, struct 
vsp1_entity *entity,
        if (i == ARRAY_SIZE(vsp1_routes))
                return -EINVAL;
 
-       mutex_init(&entity->lock);
+       spin_lock_init(&entity->lock);
 
        entity->vsp1 = vsp1;
        entity->source_pad = num_pads - 1;
@@ -228,6 +230,4 @@ void vsp1_entity_destroy(struct vsp1_entity *entity)
        if (entity->subdev.ctrl_handler)
                v4l2_ctrl_handler_free(entity->subdev.ctrl_handler);
        media_entity_cleanup(&entity->subdev.entity);
-
-       mutex_destroy(&entity->lock);
 }
diff --git a/drivers/media/platform/vsp1/vsp1_entity.h 
b/drivers/media/platform/vsp1/vsp1_entity.h
index aa20aaa58208..b634013b0958 100644
--- a/drivers/media/platform/vsp1/vsp1_entity.h
+++ b/drivers/media/platform/vsp1/vsp1_entity.h
@@ -14,7 +14,7 @@
 #define __VSP1_ENTITY_H__
 
 #include <linux/list.h>
-#include <linux/mutex.h>
+#include <linux/spinlock.h>
 
 #include <media/v4l2-subdev.h>
 
@@ -73,7 +73,7 @@ struct vsp1_entity {
 
        struct vsp1_video *video;
 
-       struct mutex lock;              /* Protects the streaming field */
+       spinlock_t lock;                /* Protects the streaming field */
        bool streaming;
 };
 
-- 
Regards,

Laurent Pinchart

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