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Commit 7b1485ba authored by NeilBrown's avatar NeilBrown
Browse files

md/raid5: use ->lock to protect accessing raid5 sysfs attributes. 



It is important that mddev->private isn't freed while
a sysfs attribute function is accessing it.

So use mddev->lock to protect the setting of ->private to NULL, and
take that lock when checking ->private for NULL and de-referencing it
in the sysfs access functions.

This only applies to the read ('show') side of access.  Write
access will be handled separately.

Signed-off-by: default avatarNeilBrown <neilb@suse.de>
parent f97fcad3

drivers/md/raid5.c

+28 −16
Original line number Diff line number Diff line
@@ -5354,11 +5354,14 @@ static void raid5d(struct md_thread *thread) 
static ssize_t

raid5_show_stripe_cache_size(struct mddev *mddev, char *page)

{

	struct r5conf *conf = mddev->private;

	struct r5conf *conf;

	int ret = 0;

	spin_lock(&mddev->lock);

	conf = mddev->private;

	if (conf)

		return sprintf(page, "%d\n", conf->max_nr_stripes);

	else

		return 0;

		ret = sprintf(page, "%d\n", conf->max_nr_stripes);

	spin_unlock(&mddev->lock);

	return ret;

}



int
@@ -5422,11 +5425,14 @@ raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR, 
static ssize_t

raid5_show_preread_threshold(struct mddev *mddev, char *page)

{

	struct r5conf *conf = mddev->private;

	struct r5conf *conf;

	int ret = 0;

	spin_lock(&mddev->lock);

	conf = mddev->private;

	if (conf)

		return sprintf(page, "%d\n", conf->bypass_threshold);

	else

		return 0;

		ret = sprintf(page, "%d\n", conf->bypass_threshold);

	spin_unlock(&mddev->lock);

	return ret;

}



static ssize_t
@@ -5456,11 +5462,14 @@ raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold, 
static ssize_t

raid5_show_skip_copy(struct mddev *mddev, char *page)

{

	struct r5conf *conf = mddev->private;

	struct r5conf *conf;

	int ret = 0;

	spin_lock(&mddev->lock);

	conf = mddev->private;

	if (conf)

		return sprintf(page, "%d\n", conf->skip_copy);

	else

		return 0;

		ret = sprintf(page, "%d\n", conf->skip_copy);

	spin_unlock(&mddev->lock);

	return ret;

}



static ssize_t
@@ -5512,11 +5521,14 @@ raid5_stripecache_active = __ATTR_RO(stripe_cache_active); 
static ssize_t

raid5_show_group_thread_cnt(struct mddev *mddev, char *page)

{

	struct r5conf *conf = mddev->private;

	struct r5conf *conf;

	int ret = 0;

	spin_lock(&mddev->lock);

	conf = mddev->private;

	if (conf)

		return sprintf(page, "%d\n", conf->worker_cnt_per_group);

	else

		return 0;

		ret = sprintf(page, "%d\n", conf->worker_cnt_per_group);

	spin_unlock(&mddev->lock);

	return ret;

}



static int alloc_thread_groups(struct r5conf *conf, int cnt,