Hi James
On 29/03/2023 12:53, James Clark wrote:
child_fwnode should be a read only property based on the DT. If it's cleared on the parent device when a child is unloaded, then when the child is loaded again the connection won't be remade.
child_dev should be cleared instead which signifies that the connection should be remade when the child_fwnode registers a new coresight_device.
Similarly the reference count shouldn't be decremented as long as the parent device exists. The correct place to drop the reference is in coresight_release_platform_data() which is already done.
Signed-off-by: James Clark james.clark@arm.com
This looks like a bug in the existing driver. Please could you keep this at the beginning of the series, so that it is easier to backport for stable ?
Also, please add :
Fixes: 37ea1ffddffa ("coresight: Use fwnode handle instead of device names") Fixes: 2af89ebacf29 ("coresight: Clear the connection field properly")
drivers/hwtracing/coresight/coresight-core.c | 10 ++-------- 1 file changed, 2 insertions(+), 8 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index bfe1b93aca4e..12cbb68e8e1c 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1414,13 +1414,8 @@ static int coresight_remove_match(struct device *dev, void *data) if (csdev->dev.fwnode == conn->dest_fwnode) { iterator->orphan = true; coresight_remove_links(iterator, conn);
/** Drop the reference to the handle for the remote* device acquired in parsing the connections from* platform data.*/fwnode_handle_put(conn->dest_fwnode);conn->dest_fwnode = NULL;
conn->dest_dev = NULL; /* No need to continue */ break;@@ -1553,7 +1548,6 @@ void coresight_release_platform_data(struct coresight_device *csdev, * is going away */ fwnode_handle_put(conns[i].dest_fwnode);
pdata->out_conns[i].dest_fwnode = NULL;
This change is not required, as we are freeing the pdata anyway. Keeping this might be beneficial if someone else comes looking for references while we are going out. I don't see how we could hit that, but just to be safe.
Suzuki