dm stats: initialize read-only module parameter

[uclinux-h8/linux.git] / drivers / md / dm-stats.c

diff --git a/drivers/md/dm-stats.c b/drivers/md/dm-stats.c
index 8ae31e8..28a9012 100644 (file)
--- 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;
 }