md: raid1/raid10: handle allocation errors during array setup.

Both raid1 and raid10 create a mempool during startup.
If the 'alloc' function for this mempool fails, unplug_slaves
is called.
If that happens when the pool is being initialised, unplug_slaves
will try to use the 'conf' structure that isn't filled in yet, and
badness will happen.

So ensure that unplug_slaves doesn't get called unless we know
that the conf structure if fully initialised.

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

drivers/md/raid1.c

@@ -64,7 +64,7 @@ static void * r1bio_pool_alloc(gfp_t gfp_flags, void *data)
 
 	/* allocate a r1bio with room for raid_disks entries in the bios array */
 	r1_bio = kzalloc(size, gfp_flags);
-	if (!r1_bio)
+	if (!r1_bio && pi->mddev)
 		unplug_slaves(pi->mddev);
 
 	return r1_bio;
@@ -1979,13 +1979,14 @@ static int run(mddev_t *mddev)
 	conf->poolinfo = kmalloc(sizeof(*conf->poolinfo), GFP_KERNEL);
 	if (!conf->poolinfo)
 		goto out_no_mem;
-	conf->poolinfo->mddev = mddev;
+	conf->poolinfo->mddev = NULL;
 	conf->poolinfo->raid_disks = mddev->raid_disks;
 	conf->r1bio_pool = mempool_create(NR_RAID1_BIOS, r1bio_pool_alloc,
 					  r1bio_pool_free,
 					  conf->poolinfo);
 	if (!conf->r1bio_pool)
 		goto out_no_mem;
+	conf->poolinfo->mddev = mddev;
 
 	spin_lock_init(&conf->device_lock);
 	mddev->queue->queue_lock = &conf->device_lock;

drivers/md/raid10.c

@@ -68,7 +68,7 @@ static void * r10bio_pool_alloc(gfp_t gfp_flags, void *data)
 
 	/* allocate a r10bio with room for raid_disks entries in the bios array */
 	r10_bio = kzalloc(size, gfp_flags);
-	if (!r10_bio)
+	if (!r10_bio && conf->mddev)
 		unplug_slaves(conf->mddev);
 
 	return r10_bio;
@@ -2096,7 +2096,6 @@ static int run(mddev_t *mddev)
 	if (!conf->tmppage)
 		goto out_free_conf;
 
-	conf->mddev = mddev;
 	conf->raid_disks = mddev->raid_disks;
 	conf->near_copies = nc;
 	conf->far_copies = fc;
@@ -2133,6 +2132,7 @@ static int run(mddev_t *mddev)
 		goto out_free_conf;
 	}
 
+	conf->mddev = mddev;
 	spin_lock_init(&conf->device_lock);
 	mddev->queue->queue_lock = &conf->device_lock;