On 02/03/2022 08:01, Mao Jinlong wrote:

It is possibe that probe failure issue happens when the device and its child_device's probe happens at the same time. In coresight_make_links, has_conns_grp is true for parent, but has_conns_grp is false for child device as has_conns_grp is set to true in coresight_create_conns_sysfs_group. The probe of parent device will fail at this condition. Add has_conns_grp check for child device before make the links and make the process from device_register to connection_create be atomic to avoid this probe failure issue.

Suggested-by: Suzuki K Poulose suzuki.poulose@arm.com Suggested-by: Mike Leach mike.leach@linaro.org Signed-off-by: Mao Jinlong quic_jinlmao@quicinc.com

---

drivers/hwtracing/coresight/coresight-core.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index 88653d1c06a4..7ce78dddfe31 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1382,7 +1382,7 @@ static int coresight_fixup_device_conns(struct coresight_device *csdev) continue; conn->child_dev = coresight_find_csdev_by_fwnode(conn->child_fwnode);

• if (conn->child_dev) {
  

• if (conn->child_dev && conn->child_dev->has_conns_grp) {
  ret = coresight_make_links(csdev, conn,
  			   conn->child_dev);
  if (ret)
  

@@ -1619,6 +1619,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) csdev->dev.fwnode = fwnode_handle_get(dev_fwnode(desc->dev)); dev_set_name(&csdev->dev, "%s", desc->name);

• mutex_lock(&coresight_mutex); ret = device_register(&csdev->dev); if (ret) { put_device(&csdev->dev);

@@ -1645,8 +1646,6 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) } }

• mutex_lock(&coresight_mutex);
• ret = coresight_create_conns_sysfs_group(csdev); if (!ret) ret = coresight_fixup_device_conns(csdev);

@@ -1666,6 +1665,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) err_free_csdev: kfree(csdev); err_out:

• mutex_unlock(&coresight_mutex);

This appears to be wrong. We may do an unlock when we didn't lock it in the first place. Please could you double check. Also, I think it may be neater to move the kfree(csdev) to the only user and return straight away from there.

Cheers Suzuki

/* Cleanup the connection information */ coresight_release_platform_data(NULL, desc->pdata); return ERR_PTR(ret);