Hi Jinlong
On 04/03/2022 08:23, 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 | 12 ++++++------ 1 file changed, 6 insertions(+), 6 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index 88653d1c06a4..b3e3bc59c09b 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)@@ -1594,7 +1594,8 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL); if (!refcnts) { ret = -ENOMEM;
goto err_free_csdev;
kfree(csdev);goto err_out;csdev->refcnt = refcnts; @@ -1619,8 +1620,10 @@ 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) {
mutex_unlock(&coresight_mutex);
- All resources are free'd explicitly via
@@ -1634,6 +1637,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) ret = etm_perf_add_symlink_sink(csdev); if (ret) {
mutex_unlock(&coresight_mutex); device_unregister(&csdev->dev); /* * As with the above, all resources are free'd@@ -1645,8 +1649,6 @@ 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);
@@ -1663,8 +1665,6 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) return csdev; -err_free_csdev:
- kfree(csdev); err_out: /* Cleanup the connection information */ coresight_release_platform_data(NULL, desc->pdata);
Could we consolidate the unlock sequence to a single point with something like this (untested):
diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c index af00dca8d1ac..198ee140c6e6 100644 --- a/drivers/hwtracing/coresight/coresight-core.c +++ b/drivers/hwtracing/coresight/coresight-core.c @@ -1571,6 +1571,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) int nr_refcnts = 1; atomic_t *refcnts = NULL; struct coresight_device *csdev; + bool registered = false;
csdev = kzalloc(sizeof(*csdev), GFP_KERNEL); if (!csdev) { @@ -1591,7 +1592,8 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) refcnts = kcalloc(nr_refcnts, sizeof(*refcnts), GFP_KERNEL); if (!refcnts) { ret = -ENOMEM; - goto err_free_csdev; + kfree(csdev); + goto err_out; }
csdev->refcnt = refcnts; @@ -1616,6 +1618,13 @@ 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);
+ /* + * 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); @@ -1623,7 +1632,7 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) * 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 || @@ -1638,11 +1647,11 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) * 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) @@ -1652,16 +1661,15 @@ struct coresight_device *coresight_register(struct coresight_desc *desc) 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);