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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: NeilBrown <neilb@suse.de>
hifive-unleashed-5.1
NeilBrown 2014-12-15 12:56:59 +11:00
parent f97fcad38f
commit 7b1485bab9
1 changed files with 28 additions and 16 deletions
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44
drivers/md/raid5.c
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@ -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,