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carma-fpga: fix lockdep warning

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Lockdep occasionally complains with the message:
INFO: HARDIRQ-safe -> HARDIRQ-unsafe lock order detected

This is caused by calling videobuf_dma_unmap() under spin_lock_irq(). To
fix the warning, we drop the lock before unmapping and freeing the
buffer.

Signed-off-by: Ira W. Snyder <iws@ovro.caltech.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Benjamin Herrenschmidt <benh@kernel.crashing.org>
This commit is contained in:
Ira Snyder 2012-01-26 10:59:54 +00:00 committed by Benjamin Herrenschmidt
parent 6d45584fdc
commit 75ff85a816
1 changed files with 11 additions and 2 deletions
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13
drivers/misc/carma/carma-fpga.c
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@ -1079,6 +1079,7 @@ static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count,
struct fpga_reader *reader = filp->private_data;
struct fpga_device *priv = reader->priv;
struct list_head *used = &priv->used;
bool drop_buffer = false;
struct data_buf *dbuf;
size_t avail;
void *data;
@ -1166,10 +1167,12 @@ have_buffer:
* One of two things has happened, the device is disabled, or the
* device has been reconfigured underneath us. In either case, we
* should just throw away the buffer.
*
* Lockdep complains if this is done under the spinlock, so we
* handle it during the unlock path.
*/
if (!priv->enabled || dbuf->size != priv->bufsize) {
videobuf_dma_unmap(priv->dev, &dbuf->vb);
data_free_buffer(dbuf);
drop_buffer = true;
goto out_unlock;
}
@ -1178,6 +1181,12 @@ have_buffer:
out_unlock:
spin_unlock_irq(&priv->lock);
if (drop_buffer) {
videobuf_dma_unmap(priv->dev, &dbuf->vb);
data_free_buffer(dbuf);
}
return count;
}