From: Mao Jinlong <quic_jinlmao@xxxxxxxxxxx> 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@xxxxxxxxxxxxxxx Suggested-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> Suggested-by: Mike Leach <mike.leach@xxxxxxxxxx> Signed-off-by: Mao Jinlong <quic_jinlmao@xxxxxxxxxxx> Link: https://lore.kernel.org/r/20220309142206.15632-1-quic_jinlmao@xxxxxxxxxxx [ Added Cc stable ] Signed-off-by: Suzuki K Poulose <suzuki.poulose@xxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- 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);
