[PATCH] driver core: ensure a device has valid node id in device_add()

Yunsheng Lin
2019-09-09T06:06:59Z

Currently a device does not belong to any of the numa nodes
(dev->numa_node is NUMA_NO_NODE) when the node id is neither
specified by fw nor by virtual device layer and the device has
no parent device.

According to discussion in [1]:
Even if a device's numa node is not specified, the device really
does belong to a node.

This patch sets the device node to node 0 in device_add() if the
device's node id is not specified and it either has no parent
device, or the parent device also does not have a valid node id.

[1] https://lkml.org/lkml/2019/9/2/466

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
Changelog RFC -> v1:
1. Drop log error message and use a "if" instead of "? :".
2. Drop the RFC tag.
---
drivers/base/core.c | 10 +++++++---
include/linux/numa.h | 2 ++
2 files changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 1669d41..f79ad20 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2107,9 +2107,13 @@ int device_add(struct device *dev)
if (kobj)
dev->kobj.parent = kobj;

- /* use parent numa_node */
- if (parent && (dev_to_node(dev) == NUMA_NO_NODE))
- set_dev_node(dev, dev_to_node(parent));
+ /* use parent numa_node or default node 0 */
+ if (!numa_node_valid(dev_to_node(dev))) {
+ if (parent && numa_node_valid(dev_to_node(parent)))
+ set_dev_node(dev, dev_to_node(parent));
+ else
+ set_dev_node(dev, 0);
+ }

/* first, register with generic layer. */
/* we require the name to be set before, and pass NULL */
diff --git a/include/linux/numa.h b/include/linux/numa.h
index 110b0e5..eccc757 100644
--- a/include/linux/numa.h
+++ b/include/linux/numa.h
@@ -13,4 +13,6 @@

#define NUMA_NO_NODE (-1)

+#define numa_node_valid(node) ((unsigned int)(node) < nr_node_ids)
+
#endif /* _LINUX_NUMA_H */
--
2.8.1