md: remove mddev_lock() from md_attr_show()

Most attributes can be read safely without any locking.
A race might lead to a slightly out-dated value, but nothing wrong.

We already have locking in some places where needed.
All that remains is can_clear_show(), behind_writes_used_show()
and action_show() which are easily fixed.

Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 10 insertions, 13 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index eb0c3b576d7d..dbbe5e6df24c 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -4042,20 +4042,21 @@ static ssize_t
 action_show(struct mddev *mddev, char *page)
 {
         char *type = "idle";
-        if (test_bit(MD_RECOVERY_FROZEN, &mddev->recovery))
+        unsigned long recovery = mddev->recovery;
+        if (test_bit(MD_RECOVERY_FROZEN, &recovery))
                 type = "frozen";
-        else if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery) ||
-            (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &mddev->recovery))) {
-                if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
+        else if (test_bit(MD_RECOVERY_RUNNING, &recovery) ||
+            (!mddev->ro && test_bit(MD_RECOVERY_NEEDED, &recovery))) {
+                if (test_bit(MD_RECOVERY_RESHAPE, &recovery))
                         type = "reshape";
-                else if (test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
-                        if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery))
+                else if (test_bit(MD_RECOVERY_SYNC, &recovery)) {
+                        if (!test_bit(MD_RECOVERY_REQUESTED, &recovery))
                                 type = "resync";
-                        else if (test_bit(MD_RECOVERY_CHECK, &mddev->recovery))
+                        else if (test_bit(MD_RECOVERY_CHECK, &recovery))
                                 type = "check";
                         else
                                 type = "repair";
-                } else if (test_bit(MD_RECOVERY_RECOVER, &mddev->recovery))
+                } else if (test_bit(MD_RECOVERY_RECOVER, &recovery))
                         type = "recover";
         }
         return sprintf(page, "%s\n", type);
@@ -4572,11 +4573,7 @@ md_attr_show(struct kobject *kobj, struct attribute *attr, char *page)
         mddev_get(mddev);
         spin_unlock(&all_mddevs_lock);
 
-        rv = mddev_lock(mddev);
-        if (!rv) {
-                rv = entry->show(mddev, page);
-                mddev_unlock(mddev);
-        }
+        rv = entry->show(mddev, page);
         mddev_put(mddev);
         return rv;
 }