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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 c7c22e4d5c "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: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens 2008-11-14 18:18:07 +01:00 committed by Martin Schwidefsky
parent 85acc407bf
commit 74af283102
1 changed files with 7 additions and 4 deletions
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11
arch/s390/kernel/topology.c
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@ -65,18 +65,21 @@ static int machine_has_topology_irq;
static struct timer_list topology_timer; static struct timer_list topology_timer;
static void set_topology_timer(void); static void set_topology_timer(void);
static DECLARE_WORK(topology_work, topology_work_fn); 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_core_map[NR_CPUS];
cpumask_t cpu_coregroup_map(unsigned int cpu) cpumask_t cpu_coregroup_map(unsigned int cpu)
{ {
struct core_info *core = &core_info; struct core_info *core = &core_info;
unsigned long flags;
cpumask_t mask; cpumask_t mask;
cpus_clear(mask); cpus_clear(mask);
if (!machine_has_topology) if (!machine_has_topology)
return cpu_present_map; return cpu_present_map;
mutex_lock(&smp_cpu_state_mutex); spin_lock_irqsave(&topology_lock, flags);
while (core) { while (core) {
if (cpu_isset(cpu, core->mask)) { if (cpu_isset(cpu, core->mask)) {
mask = core->mask; mask = core->mask;
@ -84,7 +87,7 @@ cpumask_t cpu_coregroup_map(unsigned int cpu)
} }
core = core->next; core = core->next;
} }
mutex_unlock(&smp_cpu_state_mutex); spin_unlock_irqrestore(&topology_lock, flags);
if (cpus_empty(mask)) if (cpus_empty(mask))
mask = cpumask_of_cpu(cpu); mask = cpumask_of_cpu(cpu);
return mask; return mask;
@ -133,7 +136,7 @@ static void tl_to_cores(struct tl_info *info)
union tl_entry *tle, *end; union tl_entry *tle, *end;
struct core_info *core = &core_info; struct core_info *core = &core_info;
mutex_lock(&smp_cpu_state_mutex); spin_lock_irq(&topology_lock);
clear_cores(); clear_cores();
tle = info->tle; tle = info->tle;
end = (union tl_entry *)((unsigned long)info + info->length); 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); tle = next_tle(tle);
} }
mutex_unlock(&smp_cpu_state_mutex); spin_unlock_irq(&topology_lock);
} }
static void topology_update_polarization_simple(void) static void topology_update_polarization_simple(void)