[PATCH 5.17 752/772] coresight: core: Fix coresight device probe failure issue

Greg Kroah-Hartman
2022-06-07T21:54:49Z

From: Mao Jinlong <quic_jinlmao@quicinc.com>

commit 8c1d3f79d9ca48e406b78e90e94cf09a8c076bf2 upstream.

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.

Cc: stable@vger.kernel.org
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>
Link: https://lore.kernel.org/r/20220309142206.15632-1-quic_jinlmao@quicinc.com
[ Added Cc stable ]
Signed-off-by: Suzuki K Poulose <suzuki.poulose@arm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/hwtracing/coresight/coresight-core.c | 33 ++++++++++++++++++---------
1 file changed, 22 insertions(+), 11 deletions(-)

--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -1382,7 +1382,7 @@ static int coresight_fixup_device_conns(
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)
@@ -1574,6 +1574,7 @@ struct coresight_device *coresight_regis
int nr_refcnts = 1;
atomic_t *refcnts = NULL;
struct coresight_device *csdev;
+ bool registered = false;

csdev = kzalloc(sizeof(*csdev), GFP_KERNEL);
if (!csdev) {
@@ -1594,7 +1595,8 @@ struct coresight_device *coresight_regis
refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL);
if (!refcnts) {
ret = -ENOMEM;
- goto err_free_csdev;
+ kfree(csdev);
+ goto err_out;
}

csdev->refcnt = refcnts;
@@ -1619,6 +1621,13 @@ struct coresight_device *coresight_regis
csdev->dev.fwnode = fwnode_handle_get(dev_fwnode(desc->dev));
dev_set_name(&csdev->dev, "%s", desc->name);

+ /*
+ * Make sure the device registration and the connection fixup
+ * are synchronised, so that we don't see uninitialised devices
+ * on the coresight bus while trying to resolve the connections.
+ */
+ mutex_lock(&coresight_mutex);
+
ret = device_register(&csdev->dev);
if (ret) {
put_device(&csdev->dev);
@@ -1626,7 +1635,7 @@ struct coresight_device *coresight_regis
* All resources are free'd explicitly via
* coresight_device_release(), triggered from put_device().
*/
- goto err_out;
+ goto out_unlock;
}

if (csdev->type == CORESIGHT_DEV_TYPE_SINK ||
@@ -1641,11 +1650,11 @@ struct coresight_device *coresight_regis
* from put_device(), which is in turn called from
* function device_unregister().
*/
- goto err_out;
+ goto out_unlock;
}
}
-
- mutex_lock(&coresight_mutex);
+ /* Device is now registered */
+ registered = true;

ret = coresight_create_conns_sysfs_group(csdev);
if (!ret)
@@ -1655,16 +1664,18 @@ struct coresight_device *coresight_regis
if (!ret && cti_assoc_ops && cti_assoc_ops->add)
cti_assoc_ops->add(csdev);

+out_unlock:
mutex_unlock(&coresight_mutex);
- if (ret) {
+ /* Success */
+ if (!ret)
+ return csdev;
+
+ /* Unregister the device if needed */
+ if (registered) {
coresight_unregister(csdev);
return ERR_PTR(ret);
}

- return csdev;
-
-err_free_csdev:
- kfree(csdev);
err_out:
/* Cleanup the connection information */
coresight_release_platform_data(NULL, desc->pdata);