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[PATCH 4.4 00/36] 4.4.54-stable review

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  [PATCH 4.4 00/36] 4.4.54-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
    [PATCH 4.4 18/36] ktest: Fix child exit code processing Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
    [PATCH 4.4 11/36] s390: use correct input data address for setup_randomness Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
    [PATCH 4.4 27/36] drm/ast: Call open_key before enable_mmio in POST code Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
    [PATCH 4.4 05/36] KVM: VMX: use correct vmcs_read/write for guest segment selector/base Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 09:50 +0100
    [PATCH 4.4 31/36] drm/atomic: fix an error code in mode_fixup() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 35/36] fat: fix using uninitialized fields of fat_inode/fsinfo_inode Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 08/36] s390/dcssblk: fix device size calculation in dcssblk_direct_access() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 07/36] s390/qdio: clear DSCI prior to scanning multiple input queues Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 04/36] KVM: s390: Disable dirty log retrieval for UCONTROL guests Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 36/36] drivers: hv: Turn off write permission on the hypercall page Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 34/36] libceph: use BUG() instead of BUG_ON(1) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:20 +0100
    [PATCH 4.4 23/36] xtensa: move parse_tag_fdt out of #ifdef CONFIG_BLK_DEV_INITRD Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 22/36] pwm: pca9685: Fix period change with same duty cycle Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 19/36] ceph: remove req from unsafe list when unregistering it Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 26/36] drm/ast: Fix test for VGA enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 17/36] IB/srp: Fix race conditions related to task management Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 15/36] IB/IPoIB: Add destination address when re-queue packet Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 32/36] fakelb: fix schedule while atomic Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 21/36] nlm: Ensure callback code also checks that the files match Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 13/36] mnt: Tuck mounts under others instead of creating shadow/side mounts. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 20/36] target: Fix NULL dereference during LUN lookup + active I/O shutdown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 24/36] mac80211: flush delayed work when entering suspend Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 12/36] net: mvpp2: fix DMA address calculation in mvpp2_txq_inc_put() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    [PATCH 4.4 10/36] s390: make setup_randomness work Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-03-13 10:30 +0100
    Re: [PATCH 4.4 00/36] 4.4.54-stable review Guenter Roeck <linux@roeck-us.net> - 2017-03-13 23:40 +0100

Page 2 of 2 — ← Prev page 1 [2]

#1599131 — [PATCH 4.4 13/36] mnt: Tuck mounts under others instead of creating shadow/side mounts.

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Eric W. Biederman <ebiederm@xmission.com>

commit 1064f874abc0d05eeed8993815f584d847b72486 upstream.

Ever since mount propagation was introduced in cases where a mount in
propagated to parent mount mountpoint pair that is already in use the
code has placed the new mount behind the old mount in the mount hash
table.

This implementation detail is problematic as it allows creating
arbitrary length mount hash chains.

Furthermore it invalidates the constraint maintained elsewhere in the
mount code that a parent mount and a mountpoint pair will have exactly
one mount upon them.  Making it hard to deal with and to talk about
this special case in the mount code.

Modify mount propagation to notice when there is already a mount at
the parent mount and mountpoint where a new mount is propagating to
and place that preexisting mount on top of the new mount.

Modify unmount propagation to notice when a mount that is being
unmounted has another mount on top of it (and no other children), and
to replace the unmounted mount with the mount on top of it.

Move the MNT_UMUONT test from __lookup_mnt_last into
__propagate_umount as that is the only call of __lookup_mnt_last where
MNT_UMOUNT may be set on any mount visible in the mount hash table.

These modifications allow:
 - __lookup_mnt_last to be removed.
 - attach_shadows to be renamed __attach_mnt and its shadow
   handling to be removed.
 - commit_tree to be simplified
 - copy_tree to be simplified

The result is an easier to understand tree of mounts that does not
allow creation of arbitrary length hash chains in the mount hash table.

The result is also a very slight userspace visible difference in semantics.
The following two cases now behave identically, where before order
mattered:

case 1: (explicit user action)
	B is a slave of A
	mount something on A/a , it will propagate to B/a
	and than mount something on B/a

case 2: (tucked mount)
	B is a slave of A
	mount something on B/a
	and than mount something on A/a

Histroically umount A/a would fail in case 1 and succeed in case 2.
Now umount A/a succeeds in both configurations.

This very small change in semantics appears if anything to be a bug
fix to me and my survey of userspace leads me to believe that no programs
will notice or care of this subtle semantic change.

v2: Updated to mnt_change_mountpoint to not call dput or mntput
and instead to decrement the counts directly.  It is guaranteed
that there will be other references when mnt_change_mountpoint is
called so this is safe.

v3: Moved put_mountpoint under mount_lock in attach_recursive_mnt
    As the locking in fs/namespace.c changed between v2 and v3.

v4: Reworked the logic in propagate_mount_busy and __propagate_umount
    that detects when a mount completely covers another mount.

v5: Removed unnecessary tests whose result is alwasy true in
    find_topper and attach_recursive_mnt.

v6: Document the user space visible semantic difference.

Fixes: b90fa9ae8f51 ("[PATCH] shared mount handling: bind and rbind")
Tested-by: Andrei Vagin <avagin@virtuozzo.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 fs/mount.h     |    1 
 fs/namespace.c |  109 ++++++++++++++++++++++++++++++---------------------------
 fs/pnode.c     |   61 +++++++++++++++++++++++++------
 fs/pnode.h     |    2 +
 4 files changed, 110 insertions(+), 63 deletions(-)

--- a/fs/mount.h
+++ b/fs/mount.h
@@ -86,7 +86,6 @@ static inline int is_mounted(struct vfsm
 }
 
 extern struct mount *__lookup_mnt(struct vfsmount *, struct dentry *);
-extern struct mount *__lookup_mnt_last(struct vfsmount *, struct dentry *);
 
 extern int __legitimize_mnt(struct vfsmount *, unsigned);
 extern bool legitimize_mnt(struct vfsmount *, unsigned);
--- a/fs/namespace.c
+++ b/fs/namespace.c
@@ -638,28 +638,6 @@ struct mount *__lookup_mnt(struct vfsmou
 }
 
 /*
- * find the last mount at @dentry on vfsmount @mnt.
- * mount_lock must be held.
- */
-struct mount *__lookup_mnt_last(struct vfsmount *mnt, struct dentry *dentry)
-{
-	struct mount *p, *res = NULL;
-	p = __lookup_mnt(mnt, dentry);
-	if (!p)
-		goto out;
-	if (!(p->mnt.mnt_flags & MNT_UMOUNT))
-		res = p;
-	hlist_for_each_entry_continue(p, mnt_hash) {
-		if (&p->mnt_parent->mnt != mnt || p->mnt_mountpoint != dentry)
-			break;
-		if (!(p->mnt.mnt_flags & MNT_UMOUNT))
-			res = p;
-	}
-out:
-	return res;
-}
-
-/*
  * lookup_mnt - Return the first child mount mounted at path
  *
  * "First" means first mounted chronologically.  If you create the
@@ -879,6 +857,13 @@ void mnt_set_mountpoint(struct mount *mn
 	hlist_add_head(&child_mnt->mnt_mp_list, &mp->m_list);
 }
 
+static void __attach_mnt(struct mount *mnt, struct mount *parent)
+{
+	hlist_add_head_rcu(&mnt->mnt_hash,
+			   m_hash(&parent->mnt, mnt->mnt_mountpoint));
+	list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
+}
+
 /*
  * vfsmount lock must be held for write
  */
@@ -887,28 +872,45 @@ static void attach_mnt(struct mount *mnt
 			struct mountpoint *mp)
 {
 	mnt_set_mountpoint(parent, mp, mnt);
-	hlist_add_head_rcu(&mnt->mnt_hash, m_hash(&parent->mnt, mp->m_dentry));
-	list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
+	__attach_mnt(mnt, parent);
 }
 
-static void attach_shadowed(struct mount *mnt,
-			struct mount *parent,
-			struct mount *shadows)
+void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp, struct mount *mnt)
 {
-	if (shadows) {
-		hlist_add_behind_rcu(&mnt->mnt_hash, &shadows->mnt_hash);
-		list_add(&mnt->mnt_child, &shadows->mnt_child);
-	} else {
-		hlist_add_head_rcu(&mnt->mnt_hash,
-				m_hash(&parent->mnt, mnt->mnt_mountpoint));
-		list_add_tail(&mnt->mnt_child, &parent->mnt_mounts);
-	}
+	struct mountpoint *old_mp = mnt->mnt_mp;
+	struct dentry *old_mountpoint = mnt->mnt_mountpoint;
+	struct mount *old_parent = mnt->mnt_parent;
+
+	list_del_init(&mnt->mnt_child);
+	hlist_del_init(&mnt->mnt_mp_list);
+	hlist_del_init_rcu(&mnt->mnt_hash);
+
+	attach_mnt(mnt, parent, mp);
+
+	put_mountpoint(old_mp);
+
+	/*
+	 * Safely avoid even the suggestion this code might sleep or
+	 * lock the mount hash by taking advantage of the knowledge that
+	 * mnt_change_mountpoint will not release the final reference
+	 * to a mountpoint.
+	 *
+	 * During mounting, the mount passed in as the parent mount will
+	 * continue to use the old mountpoint and during unmounting, the
+	 * old mountpoint will continue to exist until namespace_unlock,
+	 * which happens well after mnt_change_mountpoint.
+	 */
+	spin_lock(&old_mountpoint->d_lock);
+	old_mountpoint->d_lockref.count--;
+	spin_unlock(&old_mountpoint->d_lock);
+
+	mnt_add_count(old_parent, -1);
 }
 
 /*
  * vfsmount lock must be held for write
  */
-static void commit_tree(struct mount *mnt, struct mount *shadows)
+static void commit_tree(struct mount *mnt)
 {
 	struct mount *parent = mnt->mnt_parent;
 	struct mount *m;
@@ -923,7 +925,7 @@ static void commit_tree(struct mount *mn
 
 	list_splice(&head, n->list.prev);
 
-	attach_shadowed(mnt, parent, shadows);
+	__attach_mnt(mnt, parent);
 	touch_mnt_namespace(n);
 }
 
@@ -1718,7 +1720,6 @@ struct mount *copy_tree(struct mount *mn
 			continue;
 
 		for (s = r; s; s = next_mnt(s, r)) {
-			struct mount *t = NULL;
 			if (!(flag & CL_COPY_UNBINDABLE) &&
 			    IS_MNT_UNBINDABLE(s)) {
 				s = skip_mnt_tree(s);
@@ -1740,14 +1741,7 @@ struct mount *copy_tree(struct mount *mn
 				goto out;
 			lock_mount_hash();
 			list_add_tail(&q->mnt_list, &res->mnt_list);
-			mnt_set_mountpoint(parent, p->mnt_mp, q);
-			if (!list_empty(&parent->mnt_mounts)) {
-				t = list_last_entry(&parent->mnt_mounts,
-					struct mount, mnt_child);
-				if (t->mnt_mp != p->mnt_mp)
-					t = NULL;
-			}
-			attach_shadowed(q, parent, t);
+			attach_mnt(q, parent, p->mnt_mp);
 			unlock_mount_hash();
 		}
 	}
@@ -1925,10 +1919,18 @@ static int attach_recursive_mnt(struct m
 			struct path *parent_path)
 {
 	HLIST_HEAD(tree_list);
+	struct mountpoint *smp;
 	struct mount *child, *p;
 	struct hlist_node *n;
 	int err;
 
+	/* Preallocate a mountpoint in case the new mounts need
+	 * to be tucked under other mounts.
+	 */
+	smp = get_mountpoint(source_mnt->mnt.mnt_root);
+	if (IS_ERR(smp))
+		return PTR_ERR(smp);
+
 	if (IS_MNT_SHARED(dest_mnt)) {
 		err = invent_group_ids(source_mnt, true);
 		if (err)
@@ -1948,16 +1950,19 @@ static int attach_recursive_mnt(struct m
 		touch_mnt_namespace(source_mnt->mnt_ns);
 	} else {
 		mnt_set_mountpoint(dest_mnt, dest_mp, source_mnt);
-		commit_tree(source_mnt, NULL);
+		commit_tree(source_mnt);
 	}
 
 	hlist_for_each_entry_safe(child, n, &tree_list, mnt_hash) {
 		struct mount *q;
 		hlist_del_init(&child->mnt_hash);
-		q = __lookup_mnt_last(&child->mnt_parent->mnt,
-				      child->mnt_mountpoint);
-		commit_tree(child, q);
+		q = __lookup_mnt(&child->mnt_parent->mnt,
+				 child->mnt_mountpoint);
+		if (q)
+			mnt_change_mountpoint(child, smp, q);
+		commit_tree(child);
 	}
+	put_mountpoint(smp);
 	unlock_mount_hash();
 
 	return 0;
@@ -1970,6 +1975,10 @@ static int attach_recursive_mnt(struct m
 	unlock_mount_hash();
 	cleanup_group_ids(source_mnt, NULL);
  out:
+	read_seqlock_excl(&mount_lock);
+	put_mountpoint(smp);
+	read_sequnlock_excl(&mount_lock);
+
 	return err;
 }
 
--- a/fs/pnode.c
+++ b/fs/pnode.c
@@ -324,6 +324,21 @@ out:
 	return ret;
 }
 
+static struct mount *find_topper(struct mount *mnt)
+{
+	/* If there is exactly one mount covering mnt completely return it. */
+	struct mount *child;
+
+	if (!list_is_singular(&mnt->mnt_mounts))
+		return NULL;
+
+	child = list_first_entry(&mnt->mnt_mounts, struct mount, mnt_child);
+	if (child->mnt_mountpoint != mnt->mnt.mnt_root)
+		return NULL;
+
+	return child;
+}
+
 /*
  * return true if the refcount is greater than count
  */
@@ -344,9 +359,8 @@ static inline int do_refcount_check(stru
  */
 int propagate_mount_busy(struct mount *mnt, int refcnt)
 {
-	struct mount *m, *child;
+	struct mount *m, *child, *topper;
 	struct mount *parent = mnt->mnt_parent;
-	int ret = 0;
 
 	if (mnt == parent)
 		return do_refcount_check(mnt, refcnt);
@@ -361,12 +375,24 @@ int propagate_mount_busy(struct mount *m
 
 	for (m = propagation_next(parent, parent); m;
 	     		m = propagation_next(m, parent)) {
-		child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
-		if (child && list_empty(&child->mnt_mounts) &&
-		    (ret = do_refcount_check(child, 1)))
-			break;
+		int count = 1;
+		child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
+		if (!child)
+			continue;
+
+		/* Is there exactly one mount on the child that covers
+		 * it completely whose reference should be ignored?
+		 */
+		topper = find_topper(child);
+		if (topper)
+			count += 1;
+		else if (!list_empty(&child->mnt_mounts))
+			continue;
+
+		if (do_refcount_check(child, count))
+			return 1;
 	}
-	return ret;
+	return 0;
 }
 
 /*
@@ -383,7 +409,7 @@ void propagate_mount_unlock(struct mount
 
 	for (m = propagation_next(parent, parent); m;
 			m = propagation_next(m, parent)) {
-		child = __lookup_mnt_last(&m->mnt, mnt->mnt_mountpoint);
+		child = __lookup_mnt(&m->mnt, mnt->mnt_mountpoint);
 		if (child)
 			child->mnt.mnt_flags &= ~MNT_LOCKED;
 	}
@@ -401,9 +427,11 @@ static void mark_umount_candidates(struc
 
 	for (m = propagation_next(parent, parent); m;
 			m = propagation_next(m, parent)) {
-		struct mount *child = __lookup_mnt_last(&m->mnt,
+		struct mount *child = __lookup_mnt(&m->mnt,
 						mnt->mnt_mountpoint);
-		if (child && (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m))) {
+		if (!child || (child->mnt.mnt_flags & MNT_UMOUNT))
+			continue;
+		if (!IS_MNT_LOCKED(child) || IS_MNT_MARKED(m)) {
 			SET_MNT_MARK(child);
 		}
 	}
@@ -422,8 +450,8 @@ static void __propagate_umount(struct mo
 
 	for (m = propagation_next(parent, parent); m;
 			m = propagation_next(m, parent)) {
-
-		struct mount *child = __lookup_mnt_last(&m->mnt,
+		struct mount *topper;
+		struct mount *child = __lookup_mnt(&m->mnt,
 						mnt->mnt_mountpoint);
 		/*
 		 * umount the child only if the child has no children
@@ -432,6 +460,15 @@ static void __propagate_umount(struct mo
 		if (!child || !IS_MNT_MARKED(child))
 			continue;
 		CLEAR_MNT_MARK(child);
+
+		/* If there is exactly one mount covering all of child
+		 * replace child with that mount.
+		 */
+		topper = find_topper(child);
+		if (topper)
+			mnt_change_mountpoint(child->mnt_parent, child->mnt_mp,
+					      topper);
+
 		if (list_empty(&child->mnt_mounts)) {
 			list_del_init(&child->mnt_child);
 			child->mnt.mnt_flags |= MNT_UMOUNT;
--- a/fs/pnode.h
+++ b/fs/pnode.h
@@ -49,6 +49,8 @@ int get_dominating_id(struct mount *mnt,
 unsigned int mnt_get_count(struct mount *mnt);
 void mnt_set_mountpoint(struct mount *, struct mountpoint *,
 			struct mount *);
+void mnt_change_mountpoint(struct mount *parent, struct mountpoint *mp,
+			   struct mount *mnt);
 struct mount *copy_tree(struct mount *, struct dentry *, int);
 bool is_path_reachable(struct mount *, struct dentry *,
 			 const struct path *root);

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#1599134 — [PATCH 4.4 20/36] target: Fix NULL dereference during LUN lookup + active I/O shutdown

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Nicholas Bellinger <nab@linux-iscsi.org>

commit bd4e2d2907fa23a11d46217064ecf80470ddae10 upstream.

When transport_clear_lun_ref() is shutting down a se_lun via
configfs with new I/O in-flight, it's possible to trigger a
NULL pointer dereference in transport_lookup_cmd_lun() due
to the fact percpu_ref_get() doesn't do any __PERCPU_REF_DEAD
checking before incrementing lun->lun_ref.count after
lun->lun_ref has switched to atomic_t mode.

This results in a NULL pointer dereference as LUN shutdown
code in core_tpg_remove_lun() continues running after the
existing ->release() -> core_tpg_lun_ref_release() callback
completes, and clears the RCU protected se_lun->lun_se_dev
pointer.

During the OOPs, the state of lun->lun_ref in the process
which triggered the NULL pointer dereference looks like
the following on v4.1.y stable code:

struct se_lun {
  lun_link_magic = 4294932337,
  lun_status = TRANSPORT_LUN_STATUS_FREE,

  .....

  lun_se_dev = 0x0,
  lun_sep = 0x0,

  .....

  lun_ref = {
    count = {
      counter = 1
    },
    percpu_count_ptr = 3,
    release = 0xffffffffa02fa1e0 <core_tpg_lun_ref_release>,
    confirm_switch = 0x0,
    force_atomic = false,
    rcu = {
      next = 0xffff88154fa1a5d0,
      func = 0xffffffff8137c4c0 <percpu_ref_switch_to_atomic_rcu>
    }
  }
}

To address this bug, use percpu_ref_tryget_live() to ensure
once __PERCPU_REF_DEAD is visable on all CPUs and ->lun_ref
has switched to atomic_t, all new I/Os will fail to obtain
a new lun->lun_ref reference.

Also use an explicit percpu_ref_kill_and_confirm() callback
to block on ->lun_ref_comp to allow the first stage and
associated RCU grace period to complete, and then block on
->lun_ref_shutdown waiting for the final percpu_ref_put()
to drop the last reference via transport_lun_remove_cmd()
before continuing with core_tpg_remove_lun() shutdown.

Reported-by: Rob Millner <rlm@daterainc.com>
Tested-by: Rob Millner <rlm@daterainc.com>
Cc: Rob Millner <rlm@daterainc.com>
Tested-by: Vaibhav Tandon <vst@datera.io>
Cc: Vaibhav Tandon <vst@datera.io>
Tested-by: Bryant G. Ly <bryantly@linux.vnet.ibm.com>
Signed-off-by: Nicholas Bellinger <nab@linux-iscsi.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/target/target_core_device.c    |   10 ++++++++--
 drivers/target/target_core_tpg.c       |    3 ++-
 drivers/target/target_core_transport.c |   31 ++++++++++++++++++++++++++++++-
 include/target/target_core_base.h      |    1 +
 4 files changed, 41 insertions(+), 4 deletions(-)

--- a/drivers/target/target_core_device.c
+++ b/drivers/target/target_core_device.c
@@ -77,12 +77,16 @@ transport_lookup_cmd_lun(struct se_cmd *
 					&deve->read_bytes);
 
 		se_lun = rcu_dereference(deve->se_lun);
+
+		if (!percpu_ref_tryget_live(&se_lun->lun_ref)) {
+			se_lun = NULL;
+			goto out_unlock;
+		}
+
 		se_cmd->se_lun = rcu_dereference(deve->se_lun);
 		se_cmd->pr_res_key = deve->pr_res_key;
 		se_cmd->orig_fe_lun = unpacked_lun;
 		se_cmd->se_cmd_flags |= SCF_SE_LUN_CMD;
-
-		percpu_ref_get(&se_lun->lun_ref);
 		se_cmd->lun_ref_active = true;
 
 		if ((se_cmd->data_direction == DMA_TO_DEVICE) &&
@@ -96,6 +100,7 @@ transport_lookup_cmd_lun(struct se_cmd *
 			goto ref_dev;
 		}
 	}
+out_unlock:
 	rcu_read_unlock();
 
 	if (!se_lun) {
@@ -826,6 +831,7 @@ struct se_device *target_alloc_device(st
 	xcopy_lun = &dev->xcopy_lun;
 	rcu_assign_pointer(xcopy_lun->lun_se_dev, dev);
 	init_completion(&xcopy_lun->lun_ref_comp);
+	init_completion(&xcopy_lun->lun_shutdown_comp);
 	INIT_LIST_HEAD(&xcopy_lun->lun_deve_list);
 	INIT_LIST_HEAD(&xcopy_lun->lun_dev_link);
 	mutex_init(&xcopy_lun->lun_tg_pt_md_mutex);
--- a/drivers/target/target_core_tpg.c
+++ b/drivers/target/target_core_tpg.c
@@ -539,7 +539,7 @@ static void core_tpg_lun_ref_release(str
 {
 	struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
 
-	complete(&lun->lun_ref_comp);
+	complete(&lun->lun_shutdown_comp);
 }
 
 int core_tpg_register(
@@ -666,6 +666,7 @@ struct se_lun *core_tpg_alloc_lun(
 	lun->lun_link_magic = SE_LUN_LINK_MAGIC;
 	atomic_set(&lun->lun_acl_count, 0);
 	init_completion(&lun->lun_ref_comp);
+	init_completion(&lun->lun_shutdown_comp);
 	INIT_LIST_HEAD(&lun->lun_deve_list);
 	INIT_LIST_HEAD(&lun->lun_dev_link);
 	atomic_set(&lun->lun_tg_pt_secondary_offline, 0);
--- a/drivers/target/target_core_transport.c
+++ b/drivers/target/target_core_transport.c
@@ -2680,10 +2680,39 @@ void target_wait_for_sess_cmds(struct se
 }
 EXPORT_SYMBOL(target_wait_for_sess_cmds);
 
+static void target_lun_confirm(struct percpu_ref *ref)
+{
+	struct se_lun *lun = container_of(ref, struct se_lun, lun_ref);
+
+	complete(&lun->lun_ref_comp);
+}
+
 void transport_clear_lun_ref(struct se_lun *lun)
 {
-	percpu_ref_kill(&lun->lun_ref);
+	/*
+	 * Mark the percpu-ref as DEAD, switch to atomic_t mode, drop
+	 * the initial reference and schedule confirm kill to be
+	 * executed after one full RCU grace period has completed.
+	 */
+	percpu_ref_kill_and_confirm(&lun->lun_ref, target_lun_confirm);
+	/*
+	 * The first completion waits for percpu_ref_switch_to_atomic_rcu()
+	 * to call target_lun_confirm after lun->lun_ref has been marked
+	 * as __PERCPU_REF_DEAD on all CPUs, and switches to atomic_t
+	 * mode so that percpu_ref_tryget_live() lookup of lun->lun_ref
+	 * fails for all new incoming I/O.
+	 */
 	wait_for_completion(&lun->lun_ref_comp);
+	/*
+	 * The second completion waits for percpu_ref_put_many() to
+	 * invoke ->release() after lun->lun_ref has switched to
+	 * atomic_t mode, and lun->lun_ref.count has reached zero.
+	 *
+	 * At this point all target-core lun->lun_ref references have
+	 * been dropped via transport_lun_remove_cmd(), and it's safe
+	 * to proceed with the remaining LUN shutdown.
+	 */
+	wait_for_completion(&lun->lun_shutdown_comp);
 }
 
 static bool
--- a/include/target/target_core_base.h
+++ b/include/target/target_core_base.h
@@ -740,6 +740,7 @@ struct se_lun {
 	struct config_group	lun_group;
 	struct se_port_stat_grps port_stat_grps;
 	struct completion	lun_ref_comp;
+	struct completion	lun_shutdown_comp;
 	struct percpu_ref	lun_ref;
 	struct list_head	lun_dev_link;
 	struct hlist_node	link;

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#1599135 — [PATCH 4.4 24/36] mac80211: flush delayed work when entering suspend

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Matt Chen <matt.chen@intel.com>

commit a9e9200d8661c1a0be8c39f93deb383dc940de35 upstream.

The issue was found when entering suspend and resume.
It triggers a warning in:
mac80211/key.c: ieee80211_enable_keys()
...
WARN_ON_ONCE(sdata->crypto_tx_tailroom_needed_cnt ||
             sdata->crypto_tx_tailroom_pending_dec);
...

It points out sdata->crypto_tx_tailroom_pending_dec isn't cleaned up successfully
in a delayed_work during suspend. Add a flush_delayed_work to fix it.

Signed-off-by: Matt Chen <matt.chen@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 net/mac80211/pm.c |    1 +
 1 file changed, 1 insertion(+)

--- a/net/mac80211/pm.c
+++ b/net/mac80211/pm.c
@@ -168,6 +168,7 @@ int __ieee80211_suspend(struct ieee80211
 			break;
 		}
 
+		flush_delayed_work(&sdata->dec_tailroom_needed_wk);
 		drv_remove_interface(local, sdata);
 	}
 

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#1599136 — [PATCH 4.4 12/36] net: mvpp2: fix DMA address calculation in mvpp2_txq_inc_put()

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>

commit 239a3b663647869330955ec59caac0100ef9b60a upstream.

When TX descriptors are filled in, the buffer DMA address is split
between the tx_desc->buf_phys_addr field (high-order bits) and
tx_desc->packet_offset field (5 low-order bits).

However, when we re-calculate the DMA address from the TX descriptor in
mvpp2_txq_inc_put(), we do not take tx_desc->packet_offset into
account. This means that when the DMA address is not aligned on a 32
bytes boundary, we end up calling dma_unmap_single() with a DMA address
that was not the one returned by dma_map_single().

This inconsistency is detected by the kernel when DMA_API_DEBUG is
enabled. We fix this problem by properly calculating the DMA address in
mvpp2_txq_inc_put().

Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 drivers/net/ethernet/marvell/mvpp2.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

--- a/drivers/net/ethernet/marvell/mvpp2.c
+++ b/drivers/net/ethernet/marvell/mvpp2.c
@@ -993,7 +993,7 @@ static void mvpp2_txq_inc_put(struct mvp
 		txq_pcpu->buffs + txq_pcpu->txq_put_index;
 	tx_buf->skb = skb;
 	tx_buf->size = tx_desc->data_size;
-	tx_buf->phys = tx_desc->buf_phys_addr;
+	tx_buf->phys = tx_desc->buf_phys_addr + tx_desc->packet_offset;
 	txq_pcpu->txq_put_index++;
 	if (txq_pcpu->txq_put_index == txq_pcpu->size)
 		txq_pcpu->txq_put_index = 0;

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#1599137 — [PATCH 4.4 10/36] s390: make setup_randomness work

4.4-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Heiko Carstens <heiko.carstens@de.ibm.com>

commit da8fd820f389a0e29080b14c61bf5cf1d8ef5ca1 upstream.

Commit bcfcbb6bae64 ("s390: add system information as device
randomness") intended to add some virtual machine specific information
to the randomness pool.

Unfortunately it uses the page allocator before it is ready to use. In
result the page allocator always returns NULL and the setup_randomness
function never adds anything to the randomness pool.

To fix this use memblock_alloc and memblock_free instead.

Fixes: bcfcbb6bae64 ("s390: add system information as device randomness")
Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

---
 arch/s390/kernel/setup.c |    6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -805,10 +805,10 @@ static void __init setup_randomness(void
 {
 	struct sysinfo_3_2_2 *vmms;
 
-	vmms = (struct sysinfo_3_2_2 *) alloc_page(GFP_KERNEL);
-	if (vmms && stsi(vmms, 3, 2, 2) == 0 && vmms->count)
+	vmms = (struct sysinfo_3_2_2 *) memblock_alloc(PAGE_SIZE, PAGE_SIZE);
+	if (stsi(vmms, 3, 2, 2) == 0 && vmms->count)
 		add_device_randomness(&vmms, vmms->count);
-	free_page((unsigned long) vmms);
+	memblock_free((unsigned long) vmms, PAGE_SIZE);
 }
 
 /*

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#1599894

On Mon, Mar 13, 2017 at 04:39:00PM +0800, Greg Kroah-Hartman wrote:
> This is the start of the stable review cycle for the 4.4.54 release.
> There are 36 patches in this series, all will be posted as a response
> to this one.  If anyone has any issues with these being applied, please
> let me know.
> 
> Responses should be made by Wed Mar 15 08:33:39 UTC 2017.
> Anything received after that time might be too late.
> 
Build results:
	total: 149 pass: 149 fail: 0
Qemu test results:
	total: 115 pass: 115 fail: 0

Details are available at http://kerneltests.org/builders.

Guenter

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