x86/cpu/topology: Simplify cpu_mark_primary_thread()

KAGA-KOKO · KAGA-KOKO · commit 5e40fb2d4a4c · 2024-02-15T22:07:44.000+01:00
No point in creating a mask via fls(). smp_num_siblings is guaranteed to be a power of 2. So just using (smp_num_siblings - 1) has the same effect. Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Michael Kelley <mhklinux@outlook.com> Tested-by: Sohil Mehta <sohil.mehta@intel.com> Link: https://lore.kernel.org/r/20240213210252.791176581@linutronix.de
diff --git a/arch/x86/kernel/cpu/topology.c b/arch/x86/kernel/cpu/topology.c
@@ -76,10 +76,7 @@ bool arch_match_cpu_phys_id(int cpu, u64 phys_id)
 #ifdef CONFIG_SMP
 static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)
 {
-	/* Isolate the SMT bit(s) in the APICID and check for 0 */
-	u32 mask = (1U << (fls(smp_num_siblings) - 1)) - 1;
-
-	if (smp_num_siblings == 1 || !(apicid & mask))
+	if (!(apicid & (smp_num_siblings - 1)))
 		cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);
 }
 #else

Original file line number	Diff line number	Diff line change
`@@ -76,10 +76,7 @@ bool arch_match_cpu_phys_id(int cpu, u64 phys_id)`
`76`	`76`	`#ifdef CONFIG_SMP`
`77`	`77`	`static void cpu_mark_primary_thread(unsigned int cpu, unsigned int apicid)`
`78`	`78`	`{`
`79`		`- /* Isolate the SMT bit(s) in the APICID and check for 0 */`
`80`		`- u32 mask = (1U << (fls(smp_num_siblings) - 1)) - 1;`
`81`		`-`
`82`		`- if (smp_num_siblings == 1 \|\| !(apicid & mask))`
	`79`	`+ if (!(apicid & (smp_num_siblings - 1)))`
`83`	`80`	`cpumask_set_cpu(cpu, &__cpu_primary_thread_mask);`
`84`	`81`	`}`
`85`	`82`	`#else`