From: Thomas Gleixner <tglx@linutronix.de>
Date: Mon, 27 Mar 2023 15:37:39 +0000 (+0200)
Subject: x86/smpboot: Remove cpu_callin_mask
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=4a549fa1e677de5d5ed4176ffe931ff9d08d200a;p=users%2Fdwmw2%2Flinux.git
x86/smpboot: Remove cpu_callin_mask
Now that TSC synchronization is SMP function call based there is no reason
to wait for the AP to be set in smp_callin_mask. The control CPU waits for
the AP to set itself in the online mask anyway.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
---
diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
index 5b80a53a41617..925ca71fe19df 100644
--- a/arch/x86/kernel/smpboot.c
+++ b/arch/x86/kernel/smpboot.c
@@ -104,7 +104,6 @@ EXPORT_PER_CPU_SYMBOL(cpu_info);
/* All of these masks are initialized in setup_cpu_local_masks() */
static cpumask_var_t cpu_initialized_mask;
static cpumask_var_t cpu_callout_mask;
-static cpumask_var_t cpu_callin_mask;
/* Representing CPUs for which sibling maps can be computed */
static cpumask_var_t cpu_sibling_setup_mask;
@@ -167,21 +166,16 @@ static inline void smpboot_restore_warm_reset_vector(void)
*/
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();
@@ -195,7 +189,7 @@ 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();
@@ -216,11 +210,6 @@ 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 wait_for_master_cpu(int cpu)
@@ -264,11 +253,6 @@ static void notrace start_secondary(void *unused)
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() */
@@ -1101,7 +1085,7 @@ static int wait_cpu_cpumask(unsigned int cpu, const struct cpumask *mask)
* and thus wait_for_master_cpu(), then set cpu_callout_mask to allow it
* to proceed. The AP will then proceed past setting its 'callin' bit
* and end up waiting in check_tsc_sync_target() until we reach
- * do_wait_cpu_online() to tend to it.
+ * wait_cpu_online() to tend to it.
*/
static int wait_cpu_initialized(unsigned int cpu)
{
@@ -1116,20 +1100,7 @@ static int wait_cpu_initialized(unsigned int cpu)
}
/*
- * Bringup step three: Wait for the target AP to reach smp_callin().
- * The AP is not waiting for us here so we don't need to parallelise
- * this step. Not entirely clear why we care about this, since we just
- * proceed directly to TSC synchronization which is the next sync
- * point with the AP anyway.
- */
-static void wait_cpu_callin(unsigned int cpu)
-{
- while (!cpumask_test_cpu(cpu, cpu_callin_mask))
- schedule();
-}
-
-/*
- * Bringup step four: Wait for the target AP to reach set_cpu_online() in
+ * Bringup step three: Wait for the target AP to reach set_cpu_online() in
* start_secondary().
*/
static void wait_cpu_online(unsigned int cpu)
@@ -1158,14 +1129,6 @@ static int native_kick_ap(unsigned int cpu, struct task_struct *tidle)
return -EINVAL;
}
- /*
- * Already booted CPU?
- */
- if (cpumask_test_cpu(cpu, cpu_callin_mask)) {
- pr_debug("do_boot_cpu %d Already started\n", cpu);
- return -ENOSYS;
- }
-
/*
* Save current MTRR state in case it was changed since early boot
* (e.g. by the ACPI SMI) to initialize new CPUs with MTRRs in sync:
@@ -1203,7 +1166,6 @@ int native_cpu_up(unsigned int cpu, struct task_struct *tidle)
if (ret)
goto out;
- wait_cpu_callin(cpu);
wait_cpu_online(cpu);
out:
@@ -1319,7 +1281,6 @@ void __init smp_prepare_cpus_common(void)
* Setup boot CPU information
*/
smp_store_boot_cpu_info(); /* Final full version of the data */
- cpumask_copy(cpu_callin_mask, cpumask_of(0));
mb();
for_each_possible_cpu(i) {
@@ -1534,7 +1495,6 @@ __init void prefill_possible_map(void)
void __init setup_cpu_local_masks(void)
{
alloc_bootmem_cpumask_var(&cpu_initialized_mask);
- alloc_bootmem_cpumask_var(&cpu_callin_mask);
alloc_bootmem_cpumask_var(&cpu_callout_mask);
alloc_bootmem_cpumask_var(&cpu_sibling_setup_mask);
}
@@ -1598,7 +1558,6 @@ static void remove_cpu_from_maps(int cpu)
{
set_cpu_online(cpu, false);
cpumask_clear_cpu(cpu, cpu_callout_mask);
- cpumask_clear_cpu(cpu, cpu_callin_mask);
/* was set by cpu_init() */
cpumask_clear_cpu(cpu, cpu_initialized_mask);
numa_remove_cpu(cpu);