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: Peter Ujfalusi peter.ujfalusi@linux.intel.com Reviewed-by: Pierre-Louis Bossart pierre-louis.bossart@linux.intel.com Reviewed-by: Bard Liao yung-chuan.liao@linux.intel.com --- sound/soc/sof/ipc3-dtrace.c | 23 ++++++++++++++++++----- 1 file changed, 18 insertions(+), 5 deletions(-)
diff --git a/sound/soc/sof/ipc3-dtrace.c b/sound/soc/sof/ipc3-dtrace.c index 9292ff7ce1e8..1f4d7a98c8fc 100644 --- a/sound/soc/sof/ipc3-dtrace.c +++ b/sound/soc/sof/ipc3-dtrace.c @@ -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, ¶ms); @@ -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,