[media] media: coda: keep track of active instances

Determining the next free instance just by incrementing and decrementing
an instance counter does not work: if there are two instances opened,
0 and 1, and instance 0 is released, the next call to coda_open will
create a new instance with index 1, but instance 1 is already in use.
Instead, scan a bitfield of active instances to determine the first
free instance index.

Signed-off-by: Philipp Zabel <p.zabel@pengutronix.de>
Tested-by: Javier Martin <javier.martin@vista-silicon.com>
Signed-off-by: Mauro Carvalho Chehab <mchehab@redhat.com>

diff --git a/drivers/media/platform/coda.c b/drivers/media/platform/coda.c
index 01a8fe3..176741c 100644 (file)
--- a/drivers/media/platform/coda.c
+++ b/drivers/media/platform/coda.c
@@ -134,7 +134,8 @@ struct coda_dev {
        struct mutex            dev_mutex;
        struct v4l2_m2m_dev     *m2m_dev;
        struct vb2_alloc_ctx    *alloc_ctx;
-       int                     instances;
+       struct list_head        instances;
+       unsigned long           instance_mask;
 };
 
 struct coda_params {
@@ -152,6 +153,7 @@ struct coda_params {
 
 struct coda_ctx {
        struct coda_dev                 *dev;
+       struct list_head                list;
        int                             aborting;
        int                             rawstreamon;
        int                             compstreamon;
@@ -1360,14 +1362,22 @@ static int coda_queue_init(void *priv, struct vb2_queue *src_vq,
        return vb2_queue_init(dst_vq);
 }
 
+static int coda_next_free_instance(struct coda_dev *dev)
+{
+       return ffz(dev->instance_mask);
+}
+
 static int coda_open(struct file *file)
 {
        struct coda_dev *dev = video_drvdata(file);
        struct coda_ctx *ctx = NULL;
        int ret = 0;
+       int idx;
 
-       if (dev->instances >= CODA_MAX_INSTANCES)
+       idx = coda_next_free_instance(dev);
+       if (idx >= CODA_MAX_INSTANCES)
                return -EBUSY;
+       set_bit(idx, &dev->instance_mask);
 
        ctx = kzalloc(sizeof *ctx, GFP_KERNEL);
        if (!ctx)
@@ -1377,6 +1387,7 @@ static int coda_open(struct file *file)
        file->private_data = &ctx->fh;
        v4l2_fh_add(&ctx->fh);
        ctx->dev = dev;
+       ctx->idx = idx;
 
        set_default_params(ctx);
        ctx->m2m_ctx = v4l2_m2m_ctx_init(dev->m2m_dev, ctx,
@@ -1405,7 +1416,7 @@ static int coda_open(struct file *file)
        }
 
        coda_lock(ctx);
-       ctx->idx = dev->instances++;
+       list_add(&ctx->list, &dev->instances);
        coda_unlock(ctx);
 
        clk_prepare_enable(dev->clk_per);
@@ -1432,7 +1443,7 @@ static int coda_release(struct file *file)
                 ctx);
 
        coda_lock(ctx);
-       dev->instances--;
+       list_del(&ctx->list);
        coda_unlock(ctx);
 
        dma_free_coherent(&dev->plat_dev->dev, CODA_PARA_BUF_SIZE,
@@ -1443,6 +1454,7 @@ static int coda_release(struct file *file)
        clk_disable_unprepare(dev->clk_ahb);
        v4l2_fh_del(&ctx->fh);
        v4l2_fh_exit(&ctx->fh);
+       clear_bit(ctx->idx, &dev->instance_mask);
        kfree(ctx);
 
        return 0;
@@ -1826,6 +1838,7 @@ static int __devinit coda_probe(struct platform_device *pdev)
        }
 
        spin_lock_init(&dev->irqlock);
+       INIT_LIST_HEAD(&dev->instances);
 
        dev->plat_dev = pdev;
        dev->clk_per = devm_clk_get(&pdev->dev, "per");