Unverified Commit b66f9e70 authored by Peter Ujfalusi's avatar Peter Ujfalusi Committed by Mark Brown
Browse files

ASoC: SOF: ipc3-dtrace: Add helper function to update the sdev->host_offset 



We are using the READ_ONCE() on the debugfs read path for accessing
sdev->host_offset, but the set is not atomic or protected in any way.

Add a small helper to do the host_offset update and be really paranoid
about the a possible race in update

Signed-off-by: default avatarPeter Ujfalusi <peter.ujfalusi@linux.intel.com>
Reviewed-by: default avatarPierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: default avatarBard Liao <yung-chuan.liao@linux.intel.com>
Link: https://lore.kernel.org/r/20220610080119.30880-3-peter.ujfalusi@linux.intel.com


Signed-off-by: default avatarMark Brown <broonie@kernel.org>
parent 135786c3

sound/soc/sof/ipc3-dtrace.c

+18 −5
Original line number Diff line number Diff line
@@ -252,6 +252,21 @@ static int debugfs_create_trace_filter(struct snd_sof_dev *sdev) 
	return 0;

}



static bool sof_dtrace_set_host_offset(struct sof_dtrace_priv *priv, u32 new_offset)

{

	u32 host_offset = READ_ONCE(priv->host_offset);



	if (host_offset != new_offset) {

		/* This is a bit paranoid and unlikely that it is needed */

		u32 ret = cmpxchg(&priv->host_offset, host_offset, new_offset);



		if (ret == host_offset)

			return true;

	}



	return false;

}



static size_t sof_dtrace_avail(struct snd_sof_dev *sdev,

			       loff_t pos, size_t buffer_size)

{
@@ -368,7 +383,7 @@ static int dfsentry_dtrace_release(struct inode *inode, struct file *file) 


	/* avoid duplicate traces at next open */

	if (priv->dtrace_state != SOF_DTRACE_ENABLED)

		priv->host_offset = 0;

		sof_dtrace_set_host_offset(priv, 0);



	return 0;

}
@@ -444,7 +459,7 @@ static int ipc3_dtrace_enable(struct snd_sof_dev *sdev) 
	params.buffer.pages = priv->dma_trace_pages;

	params.stream_tag = 0;



	priv->host_offset = 0;

	sof_dtrace_set_host_offset(priv, 0);

	priv->dtrace_draining = false;



	ret = sof_dtrace_host_init(sdev, &priv->dmatb, &params);
@@ -559,10 +574,8 @@ int ipc3_dtrace_posn_update(struct snd_sof_dev *sdev, 
		return 0;



	if (trace_pos_update_expected(priv) &&

	    priv->host_offset != posn->host_offset) {

		priv->host_offset = posn->host_offset;

	    sof_dtrace_set_host_offset(priv, posn->host_offset))

		wake_up(&priv->trace_sleep);

	}



	if (posn->overflow != 0)

		dev_err(sdev->dev,