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Commit 9e31ced8 authored by Mauro Carvalho Chehab's avatar Mauro Carvalho Chehab
Browse files

V4L/DVB (6584): Fix read() method 



Backport read() fixes from Markus Rechberger.

Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@infradead.org>
parent a225452e

drivers/media/video/em28xx/em28xx-video.c

+22 −8
Original line number Diff line number Diff line
@@ -416,6 +416,9 @@ em28xx_v4l2_read(struct file *filp, char __user * buf, size_t count, 
	struct em28xx_fh *fh = filp->private_data;

	struct em28xx *dev = fh->dev;



	/* FIXME: read() is not prepared to allow changing the video

	   resolution while streaming. Seems a bug at em28xx_set_fmt

	 */



	if (unlikely(res_get(fh) < 0))

		return -EBUSY;
@@ -498,10 +501,26 @@ em28xx_v4l2_read(struct file *filp, char __user * buf, size_t count, 
			mutex_unlock(&dev->lock);

			return -ENODEV;

		}

		dev->video_bytesread = 0;

	}



	f = list_entry(dev->outqueue.prev, struct em28xx_frame_t, frame);



	em28xx_queue_unusedframes(dev);



	if (count > f->buf.length)

		count = f->buf.length;



	if ((dev->video_bytesread + count) > dev->frame_size)

		count = dev->frame_size - dev->video_bytesread;



	if (copy_to_user(buf, f->bufmem+dev->video_bytesread, count)) {

		em28xx_err("Error while copying to user\n");

		return -EFAULT;

	}

	dev->video_bytesread += count;



	if (dev->video_bytesread == dev->frame_size) {

		spin_lock_irqsave(&dev->queue_lock, lock_flags);

		list_for_each_entry(i, &dev->outqueue, frame)

				    i->state = F_UNUSED;
@@ -509,14 +528,9 @@ em28xx_v4l2_read(struct file *filp, char __user * buf, size_t count, 
		spin_unlock_irqrestore(&dev->queue_lock, lock_flags);



		em28xx_queue_unusedframes(dev);



	if (count > f->buf.length)

		count = f->buf.length;



	if (copy_to_user(buf, f->bufmem, count)) {

		mutex_unlock(&dev->lock);

		return -EFAULT;

		dev->video_bytesread = 0;

	}



	*f_pos += count;



	mutex_unlock(&dev->lock);

drivers/media/video/em28xx/em28xx.h

+2 −0
Original line number Diff line number Diff line
@@ -260,6 +260,7 @@ struct em28xx { 
	int vscale;		/* vertical scale factor (see datasheet) */

	int interlaced;		/* 1=interlace fileds, 0=just top fileds */

	int type;

	unsigned int video_bytesread;	/* Number of bytes read */



	unsigned long hash;	/* eeprom hash - for boards with generic ID */

	unsigned long i2c_hash;	/* i2c devicelist hash - for boards with generic ID */
@@ -268,6 +269,7 @@ struct em28xx { 
	enum em28xx_dev_state state;

	enum em28xx_stream_state stream;

	enum em28xx_io_method io;



	/* locks */

	struct mutex lock;

	spinlock_t queue_lock;