I've updated this patch following your remarks about PATCH 1/3.
About your feedback, I am not sure I understand what you mean, but I will try:
> Do not release the lock before the ringbuffer is consistent again.
If you mean that the lock should not be released while buf->data = NULL, this is *not* a problem.
A ringbuffer with NULL data *is* consistent (even though it is useless).
All functions in dmxdev.c check for a NULL pointer before calling read or write on the ringbuffer.
The same happens for the buffer of the demux.
> We should not free the old buffer before we got a new one.
I like you idea, but I did not want to change the existing logic.
You might have noticed that the new function dvb_dvr_set_buffer_size is very similar to
dvb_dmxdev_set_buffer_size (which exists already): I did not want to introduce a new logic of
resizing the ringbuffer, but I've written a function very very similar.
Maybe in a following patch one could change both of them.
> As the ring buffer can be written from an ISR, we have to use
spin_lock_irqsave/spin_unlock_irqrestore here.
Ok, I've changed the patch.
If I use spin_lock_irqsave in dvb_dvr_set_buffer_size (called via IOCTL), do I need to use the same
kind of spin_lock on all other spin_lock on the same lock (e.g. dvb_dmxdev_ts_callback)?
Let me know if I should be more aggressive and change the resize for dvr and demux at once within
this patch. Otherwise if and when this is accepted I will rearrange the code.
Andrea
diff -r 1886a5ea2f84 linux/drivers/media/dvb/dvb-core/dmxdev.c
--- a/linux/drivers/media/dvb/dvb-core/dmxdev.c Fri Mar 21 08:04:55 2008 -0300
+++ b/linux/drivers/media/dvb/dvb-core/dmxdev.c Sat Mar 22 10:12:58 2008 +0000
@@ -259,6 +259,38 @@ static ssize_t dvb_dvr_read(struct file
return ret;
}
+static int dvb_dvr_set_buffer_size(struct dmxdev *dmxdev,
+ unsigned long size)
+{
+ struct dvb_ringbuffer *buf = &dmxdev->dvr_buffer;
+ void *mem;
+
+ if (buf->size == size)
+ return 0;
+
+ dprintk("function : %s\n", __FUNCTION__);
+
+ spin_lock(&dmxdev->lock);
+ mem = buf->data;
+ buf->data = NULL;
+ buf->size = size;
+ dvb_ringbuffer_reset(buf);
+
+ spin_unlock(&dmxdev->lock);
+ vfree(mem);
+
+ if (buf->size) {
+ mem = vmalloc(dmxdev->dvr_buffer.size);
+ if (!mem)
+ return -ENOMEM;
+ spin_lock(&dmxdev->lock);
+ buf->data = mem;
+ spin_unlock(&dmxdev->lock);
+ }
+
+ return 0;
+}
+
static inline void dvb_dmxdev_filter_state_set(struct dmxdev_filter
*dmxdevfilter, int state)
{
@@ -1009,6 +1041,7 @@ static int dvb_dvr_do_ioctl(struct inode
{
struct dvb_device *dvbdev = file->private_data;
struct dmxdev *dmxdev = dvbdev->priv;
+ unsigned long arg = (unsigned long)parg;
int ret;
if (mutex_lock_interruptible(&dmxdev->mutex))
@@ -1016,8 +1049,7 @@ static int dvb_dvr_do_ioctl(struct inode
switch (cmd) {
case DMX_SET_BUFFER_SIZE:
- // FIXME: implement
- ret = 0;
+ ret = dvb_dvr_set_buffer_size(dmxdev, arg);
break;
default:
_______________________________________________
linux-dvb mailing list
linux-dvb@xxxxxxxxxxx
http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
