| Date | Mon, 13 Nov 2023 14:04:32 +1000 | Subject | Re: [PATCH RFC 11/22] drivers: base: remove unnecessary call to register_cpu_under_node() | From | Gavin Shan <> |
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On 11/7/23 20:30, Russell King (Oracle) wrote: > Since "drivers: base: Move cpu_dev_init() after node_dev_init()", we > can remove some redundant code. > > node_dev_init() will walk through the nodes calling register_one_node() > on each. This will trickle down to __register_one_node() which walks > all present CPUs, calling register_cpu_under_node() on each. > > register_cpu_under_node() will call get_cpu_device(cpu) for each, which > will return NULL until the CPU is registered using register_cpu(). This > now happens _after_ node_dev_init(). > > Therefore, calling register_cpu_under_node() from __register_one_node() > becomes a no-op, and can be removed. > > Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk> > --- > drivers/base/node.c | 7 ------- > 1 file changed, 7 deletions(-) >
__register_one_node() can be called in memory hot add path either. In that path, a new NUMA node can be presented and becomes online. Does this become a problem after the logic of associating CPU with newly added NUMA node?
Thanks, Gavin
> diff --git a/drivers/base/node.c b/drivers/base/node.c > index 493d533f8375..4d5ac7cf8757 100644 > --- a/drivers/base/node.c > +++ b/drivers/base/node.c > @@ -867,7 +867,6 @@ void register_memory_blocks_under_node(int nid, unsigned long start_pfn, > int __register_one_node(int nid) > { > int error; > - int cpu; > > node_devices[nid] = kzalloc(sizeof(struct node), GFP_KERNEL); > if (!node_devices[nid]) > @@ -875,12 +874,6 @@ int __register_one_node(int nid) > > error = register_node(node_devices[nid], nid); > > - /* link cpu under this node */ > - for_each_present_cpu(cpu) { > - if (cpu_to_node(cpu) == nid) > - register_cpu_under_node(cpu, nid); > - } > - > INIT_LIST_HEAD(&node_devices[nid]->access_list); > node_init_caches(nid); >
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