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Subject[PATCH RFC] driver core: ensure a device has valid node id in device_add()
Date
Currently a device does not belong to any of the numa nodes
(dev->numa_node is NUMA_NO_NODE) when the FW does not provide
the node id and the device has not no parent device.

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

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

There may be explicit handling out there relying on NUMA_NO_NODE,
like in nvme_probe().

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

Signed-off-by: Yunsheng Lin <linyunsheng@huawei.com>
---
drivers/base/core.c | 17 ++++++++++++++---
include/linux/numa.h | 2 ++
2 files changed, 16 insertions(+), 3 deletions(-)

diff --git a/drivers/base/core.c b/drivers/base/core.c
index 1669d41..466b8ff 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -2107,9 +2107,20 @@ 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))) {
+ int nid = parent ? dev_to_node(parent) : NUMA_NO_NODE;
+
+ if (numa_node_valid(nid)) {
+ set_dev_node(dev, nid);
+ } else {
+ if (nr_node_ids > 1U)
+ pr_err("device: '%s': has invalid NUMA node(%d)\n",
+ dev_name(dev), dev_to_node(dev));
+
+ 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
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