Commit 28c8f9fe authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'smp-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 

Pull CPU hotplug updates from Thomas Gleixner:

 - Initialize the per-CPU structures during early boot so that the state
   is consistent from the very beginning.

 - Make the virtualization hotplug state handling more robust and let
   the core bringup CPUs which timed out in an earlier attempt again.

 - Make the x86/xen CPU state tracking consistent on a failed online
   attempt, so a consecutive bringup does not fall over the inconsistent
   state.

* tag 'smp-core-2022-05-23' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  cpu/hotplug: Initialise all cpuhp_cpu_state structs earlier
  cpu/hotplug: Allow the CPU in CPU_UP_PREPARE state to be brought up again.
  x86/xen: Allow to retry if cpu_initialize_context() failed.
parents 985564eb d308077e

arch/x86/xen/smp_pv.c

+4 −1
Original line number Diff line number Diff line
@@ -260,8 +260,11 @@ cpu_initialize_context(unsigned int cpu, struct task_struct *idle) 
		return 0;



	ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);

	if (ctxt == NULL)

	if (ctxt == NULL) {

		cpumask_clear_cpu(cpu, xen_cpu_initialized_map);

		cpumask_clear_cpu(cpu, cpu_callout_mask);

		return -ENOMEM;

	}



	gdt = get_cpu_gdt_rw(cpu);

kernel/cpu.c

+13 −9
Original line number Diff line number Diff line
@@ -716,14 +716,6 @@ static int cpuhp_up_callbacks(unsigned int cpu, struct cpuhp_cpu_state *st, 
/*

 * The cpu hotplug threads manage the bringup and teardown of the cpus

 */

static void cpuhp_create(unsigned int cpu)

{

	struct cpuhp_cpu_state *st = per_cpu_ptr(&cpuhp_state, cpu);



	init_completion(&st->done_up);

	init_completion(&st->done_down);

}



static int cpuhp_should_run(unsigned int cpu)

{

	struct cpuhp_cpu_state *st = this_cpu_ptr(&cpuhp_state);
@@ -883,15 +875,27 @@ static int cpuhp_kick_ap_work(unsigned int cpu) 


static struct smp_hotplug_thread cpuhp_threads = {

	.store			= &cpuhp_state.thread,

	.create			= &cpuhp_create,

	.thread_should_run	= cpuhp_should_run,

	.thread_fn		= cpuhp_thread_fun,

	.thread_comm		= "cpuhp/%u",

	.selfparking		= true,

};



static __init void cpuhp_init_state(void)

{

	struct cpuhp_cpu_state *st;

	int cpu;



	for_each_possible_cpu(cpu) {

		st = per_cpu_ptr(&cpuhp_state, cpu);

		init_completion(&st->done_up);

		init_completion(&st->done_down);

	}

}



void __init cpuhp_threads_init(void)

{

	cpuhp_init_state();

	BUG_ON(smpboot_register_percpu_thread(&cpuhp_threads));

	kthread_unpark(this_cpu_read(cpuhp_state.thread));

}

kernel/smpboot.c

+7 −0
Original line number Diff line number Diff line
@@ -392,6 +392,13 @@ int cpu_check_up_prepare(int cpu) 
		 */

		return -EAGAIN;



	case CPU_UP_PREPARE:

		/*

		 * Timeout while waiting for the CPU to show up. Allow to try

		 * again later.

		 */

		return 0;



	default:



		/* Should not happen.  Famous last words. */