Re: [patch v3 13/36] x86/smpboot: Remove cpu_callin_mask

[Peter Zijlstra <peterz@xxxxxxxxxxxxx>]

On Mon, May 08, 2023 at 09:43:47PM +0200, Thomas Gleixner wrote:

> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c

> @@ -167,21 +166,16 @@ static inline void smpboot_restore_warm_
>   */
>  static void smp_callin(void)
>  {
> -     int cpuid;
> +     int cpuid = smp_processor_id();
>  
>       /*
>        * If waken up by an INIT in an 82489DX configuration
> -      * cpu_callout_mask guarantees we don't get here before
> -      * an INIT_deassert IPI reaches our local APIC, so it is
> -      * now safe to touch our local APIC.
> -      */
> -     cpuid = smp_processor_id();
> -
> -     /*
> -      * the boot CPU has finished the init stage and is spinning
> -      * on callin_map until we finish. We are free to set up this
> -      * CPU, first the APIC. (this is probably redundant on most
> -      * boards)
> +      * cpu_callout_mask guarantees we don't get here before an
> +      * INIT_deassert IPI reaches our local APIC, so it is now safe to
> +      * touch our local APIC.
> +      *
> +      * Set up this CPU, first the APIC, which is probably redundant on
> +      * most boards.
>        */
>       apic_ap_setup();
>  
> @@ -192,7 +186,7 @@ static void smp_callin(void)
>        * The topology information must be up to date before
>        * calibrate_delay() and notify_cpu_starting().
>        */
> -     set_cpu_sibling_map(raw_smp_processor_id());
> +     set_cpu_sibling_map(cpuid);
>  
>       ap_init_aperfmperf();
>  
> @@ -205,11 +199,6 @@ static void smp_callin(void)
>        * state (CPUHP_ONLINE in the case of serial bringup).
>        */
>       notify_cpu_starting(cpuid);
> -
> -     /*
> -      * Allow the master to continue.
> -      */
> -     cpumask_set_cpu(cpuid, cpu_callin_mask);
>  }
>  
>  static void ap_calibrate_delay(void)
> @@ -268,11 +257,6 @@ static void notrace start_secondary(void
>       rcu_cpu_starting(raw_smp_processor_id());
>       x86_cpuinit.early_percpu_clock_init();
>  
> -     /*
> -      * Sync point with wait_cpu_callin(). The AP doesn't wait here
> -      * but just sets the bit to let the controlling CPU (BSP) know that
> -      * it's got this far.
> -      */
>       smp_callin();
>  
>       /* Otherwise gcc will move up smp_processor_id() before cpu_init() */

Good riddance to that mask; however is smp_callin() still an appropriate
name for that function?

Would smp_starting() -- seeing how this kicks of CPU_STARTING not be a
better name?