x86/smpboot: moves x86_topology to static initialize and truncate

The #ifdeffery and the initializers in build_sched_topology() are just
disgusting.

Statically initialize the domain levels in the topology array and let
build_sched_topology() invalidate the package domain level when NUMA in
package is available.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Li Chen <chenl311@chinatelecom.cn>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: K Prateek Nayak <kprateek.nayak@amd.com>
Tested-by: K Prateek Nayak <kprateek.nayak@amd.com>
Link: https://lore.kernel.org/r/20250710105715.66594-4-me@linux.beauty

diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 30e6df2b4db6dea041b05fc99c8fc319ce713873..8038286454cf1bc22377546aa9362bf952aac886 100644 (file)
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -478,32 +478,30 @@ static int x86_cluster_flags(void)
  */
 static bool x86_has_numa_in_package;
 
-static struct sched_domain_topology_level x86_topology[6];
-
-static void __init build_sched_topology(void)
-{
-       int i = 0;
-
-       x86_topology[i++] = SDTL_INIT(cpu_smt_mask, cpu_smt_flags, SMT);
+static struct sched_domain_topology_level x86_topology[] = {
+       SDTL_INIT(cpu_smt_mask, cpu_smt_flags, SMT),
 #ifdef CONFIG_SCHED_CLUSTER
-       x86_topology[i++] = SDTL_INIT(cpu_clustergroup_mask, x86_cluster_flags, CLS);
+       SDTL_INIT(cpu_clustergroup_mask, x86_cluster_flags, CLS),
 #endif
 #ifdef CONFIG_SCHED_MC
-       x86_topology[i++] = SDTL_INIT(cpu_coregroup_mask, x86_core_flags, MC);
+       SDTL_INIT(cpu_coregroup_mask, x86_core_flags, MC),
 #endif
-       /*
-        * When there is NUMA topology inside the package skip the PKG domain
-        * since the NUMA domains will auto-magically create the right spanning
-        * domains based on the SLIT.
-        */
-       if (!x86_has_numa_in_package)
-               x86_topology[i++] = SDTL_INIT(cpu_cpu_mask, x86_sched_itmt_flags, PKG);
+       SDTL_INIT(cpu_cpu_mask, x86_sched_itmt_flags, PKG),
+       { NULL },
+};
 
+static void __init build_sched_topology(void)
+{
        /*
-        * There must be one trailing NULL entry left.
+        * When there is NUMA topology inside the package invalidate the
+        * PKG domain since the NUMA domains will auto-magically create the
+        * right spanning domains based on the SLIT.
         */
-       BUG_ON(i >= ARRAY_SIZE(x86_topology) - 1);
+       if (x86_has_numa_in_package) {
+               unsigned int pkgdom = ARRAY_SIZE(x86_topology) - 2;
 
+               memset(&x86_topology[pkgdom], 0, sizeof(x86_topology[pkgdom]));
+       }
        set_sched_topology(x86_topology);
 }