Commit a052096b authored by Sven Schnelle's avatar Sven Schnelle Committed by Heiko Carstens
Browse files

s390/topology: fix topology information when calling cpu hotplug notifiers 



The cpu hotplug notifiers are called without updating the core/thread
masks when a new CPU is added. This causes problems with code setting
up data structures in a cpu hotplug notifier, and relying on that later
in normal code.

This caused a crash in the new core scheduling code (SCHED_CORE),
where rq->core was set up in a notifier depending on cpu masks.

To fix this, add a cpu_setup_mask which is used in update_cpu_masks()
instead of the cpu_online_mask to determine whether the cpu masks should
be set for a certain cpu. Also move update_cpu_masks() to update the
masks before calling notify_cpu_starting() so that the notifiers are
seeing the updated masks.

Signed-off-by: default avatarSven Schnelle <svens@linux.ibm.com>
Cc: <stable@vger.kernel.org>
[hca@linux.ibm.com: get rid of cpu_online_mask handling]
Signed-off-by: default avatarHeiko Carstens <hca@linux.ibm.com>
parent 88b60426

arch/s390/include/asm/smp.h

+1 −0
Original line number Diff line number Diff line
@@ -18,6 +18,7 @@ extern struct mutex smp_cpu_state_mutex; 
extern unsigned int smp_cpu_mt_shift;

extern unsigned int smp_cpu_mtid;

extern __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS];

extern cpumask_t cpu_setup_mask;



extern int __cpu_up(unsigned int cpu, struct task_struct *tidle);

arch/s390/kernel/smp.c

+7 −2
Original line number Diff line number Diff line
@@ -95,6 +95,7 @@ __vector128 __initdata boot_cpu_vector_save_area[__NUM_VXRS]; 
#endif



static unsigned int smp_max_threads __initdata = -1U;

cpumask_t cpu_setup_mask;



static int __init early_nosmt(char *s)

{
@@ -902,13 +903,14 @@ static void smp_start_secondary(void *cpuvoid) 
	vtime_init();

	vdso_getcpu_init();

	pfault_init();

	cpumask_set_cpu(cpu, &cpu_setup_mask);

	update_cpu_masks();

	notify_cpu_starting(cpu);

	if (topology_cpu_dedicated(cpu))

		set_cpu_flag(CIF_DEDICATED_CPU);

	else

		clear_cpu_flag(CIF_DEDICATED_CPU);

	set_cpu_online(cpu, true);

	update_cpu_masks();

	inc_irq_stat(CPU_RST);

	local_irq_enable();

	cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
@@ -950,10 +952,13 @@ early_param("possible_cpus", _setup_possible_cpus); 
int __cpu_disable(void)

{

	unsigned long cregs[16];

	int cpu;



	/* Handle possible pending IPIs */

	smp_handle_ext_call();

	set_cpu_online(smp_processor_id(), false);

	cpu = smp_processor_id();

	set_cpu_online(cpu, false);

	cpumask_clear_cpu(cpu, &cpu_setup_mask);

	update_cpu_masks();

	/* Disable pseudo page faults on this cpu. */

	pfault_fini();

arch/s390/kernel/topology.c

+7 −6
Original line number Diff line number Diff line
@@ -67,7 +67,7 @@ static void cpu_group_map(cpumask_t *dst, struct mask_info *info, unsigned int c 
	static cpumask_t mask;



	cpumask_clear(&mask);

	if (!cpu_online(cpu))

	if (!cpumask_test_cpu(cpu, &cpu_setup_mask))

		goto out;

	cpumask_set_cpu(cpu, &mask);

	switch (topology_mode) {
@@ -88,7 +88,7 @@ static void cpu_group_map(cpumask_t *dst, struct mask_info *info, unsigned int c 
	case TOPOLOGY_MODE_SINGLE:

		break;

	}

	cpumask_and(&mask, &mask, cpu_online_mask);

	cpumask_and(&mask, &mask, &cpu_setup_mask);

out:

	cpumask_copy(dst, &mask);

}
@@ -99,16 +99,16 @@ static void cpu_thread_map(cpumask_t *dst, unsigned int cpu) 
	int i;



	cpumask_clear(&mask);

	if (!cpu_online(cpu))

	if (!cpumask_test_cpu(cpu, &cpu_setup_mask))

		goto out;

	cpumask_set_cpu(cpu, &mask);

	if (topology_mode != TOPOLOGY_MODE_HW)

		goto out;

	cpu -= cpu % (smp_cpu_mtid + 1);

	for (i = 0; i <= smp_cpu_mtid; i++)

		if (cpu_present(cpu + i))

	for (i = 0; i <= smp_cpu_mtid; i++) {

		if (cpumask_test_cpu(cpu + i, &cpu_setup_mask))

			cpumask_set_cpu(cpu + i, &mask);

	cpumask_and(&mask, &mask, cpu_online_mask);

	}

out:

	cpumask_copy(dst, &mask);

}
@@ -569,6 +569,7 @@ void __init topology_init_early(void) 
	alloc_masks(info, &book_info, 2);

	alloc_masks(info, &drawer_info, 3);

out:

	cpumask_set_cpu(0, &cpu_setup_mask);

	__arch_update_cpu_topology();

	__arch_update_dedicated_flag(NULL);

}