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Commit 75ff85a8 authored by Ira Snyder's avatar Ira Snyder Committed by Benjamin Herrenschmidt
Browse files

carma-fpga: fix lockdep warning 



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: default avatarIra W. Snyder <iws@ovro.caltech.edu>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: default avatarBenjamin Herrenschmidt <benh@kernel.crashing.org>
parent 6d45584f

drivers/misc/carma/carma-fpga.c

+11 −2
Original line number Diff line number Diff line
@@ -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 @@ static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count, 
	 * 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 @@ static ssize_t data_read(struct file *filp, char __user *ubuf, size_t count, 


out_unlock:

	spin_unlock_irq(&priv->lock);



	if (drop_buffer) {

		videobuf_dma_unmap(priv->dev, &dbuf->vb);

		data_free_buffer(dbuf);

	}



	return count;

}