From a7a3f08dc24690ae00c75cfe4b4701a970dd0155 Mon Sep 17 00:00:00 2001 From: NeilBrown Date: Tue, 11 Dec 2012 13:35:54 +1100 Subject: [PATCH] md: close race between removing and adding a device. When we remove a device from an md array, the final removal of the "dev-XX" sys entry is run asynchronously. If we then re-add that device immediately before the worker thread gets to run, we can end up trying to add the "dev-XX" sysfs entry back before it has been removed. So in both places where we add a device, call flush_workqueue(md_misc_wq); before taking the md lock (as holding the md lock can prevent removal to complete). Signed-off-by: NeilBrown --- drivers/md/md.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/drivers/md/md.c b/drivers/md/md.c index 89dbd44..8b0e3d2 100644 --- a/drivers/md/md.c +++ b/drivers/md/md.c @@ -4752,6 +4752,8 @@ md_attr_store(struct kobject *kobj, struct attribute *attr, } mddev_get(mddev); spin_unlock(&all_mddevs_lock); + if (entry->store == new_dev_store) + flush_workqueue(md_misc_wq); rv = mddev_lock(mddev); if (!rv) { rv = entry->store(mddev, page, length); @@ -6397,6 +6399,10 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, goto abort; } + if (cmd == ADD_NEW_DISK) + /* need to ensure md_delayed_delete() has completed */ + flush_workqueue(md_misc_wq); + err = mddev_lock(mddev); if (err) { printk(KERN_INFO -- 2.7.4