diff options
Diffstat (limited to 'drivers/md/dm-stats.c')
| -rw-r--r-- | drivers/md/dm-stats.c | 24 |
1 files changed, 18 insertions, 6 deletions
diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c index 8ae31e8d3d6..28a90122a5a 100644 --- a/drivers/md/dm-stats.c +++ b/drivers/md/dm-stats.c @@ -451,19 +451,26 @@ static void dm_stat_for_entry(struct dm_stat *s, size_t entry, struct dm_stat_percpu *p; /* - * For strict correctness we should use local_irq_disable/enable + * For strict correctness we should use local_irq_save/restore * instead of preempt_disable/enable. * - * This is racy if the driver finishes bios from non-interrupt - * context as well as from interrupt context or from more different - * interrupts. + * preempt_disable/enable is racy if the driver finishes bios + * from non-interrupt context as well as from interrupt context + * or from more different interrupts. * - * However, the race only results in not counting some events, - * so it is acceptable. + * On 64-bit architectures the race only results in not counting some + * events, so it is acceptable. On 32-bit architectures the race could + * cause the counter going off by 2^32, so we need to do proper locking + * there. * * part_stat_lock()/part_stat_unlock() have this race too. */ +#if BITS_PER_LONG == 32 + unsigned long flags; + local_irq_save(flags); +#else preempt_disable(); +#endif p = &s->stat_percpu[smp_processor_id()][entry]; if (!end) { @@ -478,7 +485,11 @@ static void dm_stat_for_entry(struct dm_stat *s, size_t entry, p->ticks[idx] += duration; } +#if BITS_PER_LONG == 32 + local_irq_restore(flags); +#else preempt_enable(); +#endif } static void __dm_stat_bio(struct dm_stat *s, unsigned long bi_rw, @@ -953,6 +964,7 @@ int dm_stats_message(struct mapped_device *md, unsigned argc, char **argv, int __init dm_statistics_init(void) { + shared_memory_amount = 0; dm_stat_need_rcu_barrier = 0; return 0; } |