Re: [PATCH v2 11/14] futex: Implement FUTEX2_NUMA

On Tue, Aug 08 2023 at 10:54, Peter Zijlstra wrote:

On Mon, Aug 07, 2023 at 11:11:04PM +0200, Thomas Gleixner wrote:

quoted

On Mon, Aug 07 2023 at 14:18, Peter Zijlstra wrote:

quoted

 /**
  * futex_hash - Return the hash bucket in the global hash
  * @key:	Pointer to the futex key for which the hash is calculated

@@ -114,10 +137,29 @@ late_initcall(fail_futex_debugfs);
  */
 struct futex_hash_bucket *futex_hash(union futex_key *key)
 {
-	u32 hash = jhash2((u32 *)key, offsetof(typeof(*key), both.offset) / 4,
+	u32 hash = jhash2((u32 *)key,
+			  offsetof(typeof(*key), both.offset) / sizeof(u32),
 			  key->both.offset);
+	int node = key->both.node;
+
+	if (node == -1) {

NUMA_NO_NODE please all over the place.

Ah, so our (futex2) ABI states this needs to be -1, but in theory
someone could come along and change the kernel internal NUMA_NO_NODE to
something else.

That is, I explicitly chose not to use it. I can of course, because as
of now these values do match.

Fair enough, but can we at least have a proper define in the futex2 ABI
please?