Hi,
在 2024/01/30 15:37, Song Liu 写道:
On Thu, Jan 11, 2024 at 11:10 PM Gui-Dong Han 2045gemini@gmail.com wrote:
[...]
raid5_release_stripe(sh);
conf->max_nr_stripes++;
WRITE_ONCE(conf->max_nr_stripes, conf->max_nr_stripes + 1);This is weird. We are reading max_nr_stripes without READ_ONCE.
We don't need READ_ONCE() here because writers are protected by 'cache_size_mutex', there are no concurrent writers, it's safe to read 'max_nr_stripes' directly.
Thanks, Kuai
return 1;}
@@ -2707,7 +2707,7 @@ static int drop_one_stripe(struct r5conf *conf) shrink_buffers(sh); free_stripe(conf->slab_cache, sh); atomic_dec(&conf->active_stripes);
conf->max_nr_stripes--;
WRITE_ONCE(conf->max_nr_stripes, conf->max_nr_stripes - 1);Same here.
return 1;}
@@ -6820,7 +6820,7 @@ raid5_set_cache_size(struct mddev *mddev, int size) if (size <= 16 || size > 32768) return -EINVAL;
conf->min_nr_stripes = size;
WRITE_ONCE(conf->min_nr_stripes, size); mutex_lock(&conf->cache_size_mutex); while (size < conf->max_nr_stripes && drop_one_stripe(conf))@@ -6832,7 +6832,7 @@ raid5_set_cache_size(struct mddev *mddev, int size) mutex_lock(&conf->cache_size_mutex); while (size > conf->max_nr_stripes) if (!grow_one_stripe(conf, GFP_KERNEL)) {
conf->min_nr_stripes = conf->max_nr_stripes;
WRITE_ONCE(conf->min_nr_stripes, conf->max_nr_stripes);And here.
result = -ENOMEM; break; }Thanks, Song .