Upgrade to 4.4.50-rt62

The current kernel is based on rt kernel v4.4.6-rt14. We will upgrade it
to 4.4.50-rt62.
The command to achieve it is:
a) Clone a git repo from
git://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git

b) Get the diff between this two changesets:
git diff 640eca2901f3435e616157b11379d3223a44b391
705619beeea1b0b48219a683fd1a901a86fdaf5e

where the two commits are:
[yjiang5@jnakajim-build linux-stable-rt]$ git show --oneline --name-only
640eca2901f3435e616157b11379d3223a44b391
640eca2901f3 v4.4.6-rt14
localversion-rt
[yjiang5@jnakajim-build linux-stable-rt]$ git show --oneline --name-only
705619beeea1b0b48219a683fd1a901a86fdaf5e
705619beeea1 Linux 4.4.50-rt62
localversion-rt

c) One patch has been backported thus revert the patch before applying.

 filterdiff -p1 -x scripts/package/Makefile
~/tmp/v4.4.6-rt14-4.4.50-rt62.diff  |patch -p1 --dry-run

Upstream status: backport

Change-Id: I244d57a32f6066e5a5b9915f9fbf99e7bbca6e01
Signed-off-by: Yunhong Jiang <yunhong.jiang@linux.intel.com>

1 files changed, 34 insertions, 14 deletions

diff --git a/kernel/drivers/md/bcache/super.c b/kernel/drivers/md/bcache/super.c
index 8d0ead98e..3d5c0ba13 100644
--- a/kernel/drivers/md/bcache/super.c
+++ b/kernel/drivers/md/bcache/super.c
@@ -1015,8 +1015,12 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)
 	 */
 	atomic_set(&dc->count, 1);
 
-	if (bch_cached_dev_writeback_start(dc))
+	/* Block writeback thread, but spawn it */
+	down_write(&dc->writeback_lock);
+	if (bch_cached_dev_writeback_start(dc)) {
+		up_write(&dc->writeback_lock);
 		return -ENOMEM;
+	}
 
 	if (BDEV_STATE(&dc->sb) == BDEV_STATE_DIRTY) {
 		bch_sectors_dirty_init(dc);
@@ -1028,6 +1032,9 @@ int bch_cached_dev_attach(struct cached_dev *dc, struct cache_set *c)
 	bch_cached_dev_run(dc);
 	bcache_device_link(&dc->disk, c, "bdev");
 
+	/* Allow the writeback thread to proceed */
+	up_write(&dc->writeback_lock);
+
 	pr_info("Caching %s as %s on set %pU",
 		bdevname(dc->bdev, buf), dc->disk.disk->disk_name,
 		dc->disk.c->sb.set_uuid);
@@ -1366,6 +1373,9 @@ static void cache_set_flush(struct closure *cl)
 	struct btree *b;
 	unsigned i;
 
+	if (!c)
+		closure_return(cl);
+
 	bch_cache_accounting_destroy(&c->accounting);
 
 	kobject_put(&c->internal);
@@ -1808,7 +1818,7 @@ static int cache_alloc(struct cache_sb *sb, struct cache *ca)
 	free = roundup_pow_of_two(ca->sb.nbuckets) >> 10;
 
 	if (!init_fifo(&ca->free[RESERVE_BTREE], 8, GFP_KERNEL) ||
-	    !init_fifo(&ca->free[RESERVE_PRIO], prio_buckets(ca), GFP_KERNEL) ||
+	    !init_fifo_exact(&ca->free[RESERVE_PRIO], prio_buckets(ca), GFP_KERNEL) ||
 	    !init_fifo(&ca->free[RESERVE_MOVINGGC], free, GFP_KERNEL) ||
 	    !init_fifo(&ca->free[RESERVE_NONE], free, GFP_KERNEL) ||
 	    !init_fifo(&ca->free_inc,	free << 2, GFP_KERNEL) ||
@@ -1828,11 +1838,12 @@ static int cache_alloc(struct cache_sb *sb, struct cache *ca)
 	return 0;
 }
 
-static void register_cache(struct cache_sb *sb, struct page *sb_page,
+static int register_cache(struct cache_sb *sb, struct page *sb_page,
 				struct block_device *bdev, struct cache *ca)
 {
 	char name[BDEVNAME_SIZE];
-	const char *err = "cannot allocate memory";
+	const char *err = NULL;
+	int ret = 0;
 
 	memcpy(&ca->sb, sb, sizeof(struct cache_sb));
 	ca->bdev = bdev;
@@ -1847,27 +1858,35 @@ static void register_cache(struct cache_sb *sb, struct page *sb_page,
 	if (blk_queue_discard(bdev_get_queue(ca->bdev)))
 		ca->discard = CACHE_DISCARD(&ca->sb);
 
-	if (cache_alloc(sb, ca) != 0)
+	ret = cache_alloc(sb, ca);
+	if (ret != 0)
 		goto err;
 
-	err = "error creating kobject";
-	if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache"))
-		goto err;
+	if (kobject_add(&ca->kobj, &part_to_dev(bdev->bd_part)->kobj, "bcache")) {
+		err = "error calling kobject_add";
+		ret = -ENOMEM;
+		goto out;
+	}
 
 	mutex_lock(&bch_register_lock);
 	err = register_cache_set(ca);
 	mutex_unlock(&bch_register_lock);
 
-	if (err)
-		goto err;
+	if (err) {
+		ret = -ENODEV;
+		goto out;
+	}
 
 	pr_info("registered cache device %s", bdevname(bdev, name));
+
 out:
 	kobject_put(&ca->kobj);
-	return;
+
 err:
-	pr_notice("error opening %s: %s", bdevname(bdev, name), err);
-	goto out;
+	if (err)
+		pr_notice("error opening %s: %s", bdevname(bdev, name), err);
+
+	return ret;
 }
 
 /* Global interfaces/init */
@@ -1965,7 +1984,8 @@ static ssize_t register_bcache(struct kobject *k, struct kobj_attribute *attr,
 		if (!ca)
 			goto err_close;
 
-		register_cache(sb, sb_page, bdev, ca);
+		if (register_cache(sb, sb_page, bdev, ca) != 0)
+			goto err_close;
 	}
 out:
 	if (sb_page)