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Commit 74af2831 authored by Heiko Carstens's avatar Heiko Carstens Committed by Martin Schwidefsky
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[S390] cpu topology: fix locking 



cpu_coregroup_map used to grab a mutex on s390 since it was only
called from process context.
Since c7c22e4d "block: add support
for IO CPU affinity" this is not true anymore.
It now also gets called from softirq context.

To prevent possible deadlocks change this in architecture code and
use a spinlock instead of a mutex.

Cc: stable@kernel.org
Cc: Jens Axboe <jens.axboe@oracle.com>
Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: default avatarMartin Schwidefsky <schwidefsky@de.ibm.com>
parent 85acc407

arch/s390/kernel/topology.c

+7 −4
Original line number Diff line number Diff line
@@ -65,18 +65,21 @@ static int machine_has_topology_irq; 
static struct timer_list topology_timer;

static void set_topology_timer(void);

static DECLARE_WORK(topology_work, topology_work_fn);

/* topology_lock protects the core linked list */

static DEFINE_SPINLOCK(topology_lock);



cpumask_t cpu_core_map[NR_CPUS];



cpumask_t cpu_coregroup_map(unsigned int cpu)

{

	struct core_info *core = &core_info;

	unsigned long flags;

	cpumask_t mask;



	cpus_clear(mask);

	if (!machine_has_topology)

		return cpu_present_map;

	mutex_lock(&smp_cpu_state_mutex);

	spin_lock_irqsave(&topology_lock, flags);

	while (core) {

		if (cpu_isset(cpu, core->mask)) {

			mask = core->mask;
@@ -84,7 +87,7 @@ cpumask_t cpu_coregroup_map(unsigned int cpu) 
		}

		core = core->next;

	}

	mutex_unlock(&smp_cpu_state_mutex);

	spin_unlock_irqrestore(&topology_lock, flags);

	if (cpus_empty(mask))

		mask = cpumask_of_cpu(cpu);

	return mask;
@@ -133,7 +136,7 @@ static void tl_to_cores(struct tl_info *info) 
	union tl_entry *tle, *end;

	struct core_info *core = &core_info;



	mutex_lock(&smp_cpu_state_mutex);

	spin_lock_irq(&topology_lock);

	clear_cores();

	tle = info->tle;

	end = (union tl_entry *)((unsigned long)info + info->length);
@@ -157,7 +160,7 @@ static void tl_to_cores(struct tl_info *info) 
		}

		tle = next_tle(tle);

	}

	mutex_unlock(&smp_cpu_state_mutex);

	spin_unlock_irq(&topology_lock);

}



static void topology_update_polarization_simple(void)