Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 472 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_auth.c b/drivers/gpu/drm/drm_auth.c
new file mode 100644
index 000000000..cf92a9ae8
--- /dev/null
+++ b/drivers/gpu/drm/drm_auth.c
@@ -0,0 +1,472 @@
+/*
+ * Created: Tue Feb  2 08:37:54 1999 by faith@valinux.com
+ *
+ * Copyright 1999 Precision Insight, Inc., Cedar Park, Texas.
+ * Copyright 2000 VA Linux Systems, Inc., Sunnyvale, California.
+ * All Rights Reserved.
+ *
+ * Author Rickard E. (Rik) Faith <faith@valinux.com>
+ * Author Gareth Hughes <gareth@valinux.com>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * VA LINUX SYSTEMS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM, DAMAGES OR
+ * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
+ * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
+ * OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include <linux/slab.h>
+
+#include <drm/drm_auth.h>
+#include <drm/drm_drv.h>
+#include <drm/drm_file.h>
+#include <drm/drm_lease.h>
+#include <drm/drm_print.h>
+
+#include "drm_internal.h"
+#include "drm_legacy.h"
+
+/**
+ * DOC: master and authentication
+ *
+ * &struct drm_master is used to track groups of clients with open
+ * primary/legacy device nodes. For every &struct drm_file which has had at
+ * least once successfully became the device master (either through the
+ * SET_MASTER IOCTL, or implicitly through opening the primary device node when
+ * no one else is the current master that time) there exists one &drm_master.
+ * This is noted in &drm_file.is_master. All other clients have just a pointer
+ * to the &drm_master they are associated with.
+ *
+ * In addition only one &drm_master can be the current master for a &drm_device.
+ * It can be switched through the DROP_MASTER and SET_MASTER IOCTL, or
+ * implicitly through closing/opening the primary device node. See also
+ * drm_is_current_master().
+ *
+ * Clients can authenticate against the current master (if it matches their own)
+ * using the GETMAGIC and AUTHMAGIC IOCTLs. Together with exchanging masters,
+ * this allows controlled access to the device for an entire group of mutually
+ * trusted clients.
+ */
+
+static bool drm_is_current_master_locked(struct drm_file *fpriv)
+{
+	lockdep_assert_once(lockdep_is_held(&fpriv->master_lookup_lock) ||
+			    lockdep_is_held(&fpriv->minor->dev->master_mutex));
+
+	return fpriv->is_master && drm_lease_owner(fpriv->master) == fpriv->minor->dev->master;
+}
+
+/**
+ * drm_is_current_master - checks whether @priv is the current master
+ * @fpriv: DRM file private
+ *
+ * Checks whether @fpriv is current master on its device. This decides whether a
+ * client is allowed to run DRM_MASTER IOCTLs.
+ *
+ * Most of the modern IOCTL which require DRM_MASTER are for kernel modesetting
+ * - the current master is assumed to own the non-shareable display hardware.
+ */
+bool drm_is_current_master(struct drm_file *fpriv)
+{
+	bool ret;
+
+	spin_lock(&fpriv->master_lookup_lock);
+	ret = drm_is_current_master_locked(fpriv);
+	spin_unlock(&fpriv->master_lookup_lock);
+
+	return ret;
+}
+EXPORT_SYMBOL(drm_is_current_master);
+
+int drm_getmagic(struct drm_device *dev, void *data, struct drm_file *file_priv)
+{
+	struct drm_auth *auth = data;
+	int ret = 0;
+
+	mutex_lock(&dev->master_mutex);
+	if (!file_priv->magic) {
+		ret = idr_alloc(&file_priv->master->magic_map, file_priv,
+				1, 0, GFP_KERNEL);
+		if (ret >= 0)
+			file_priv->magic = ret;
+	}
+	auth->magic = file_priv->magic;
+	mutex_unlock(&dev->master_mutex);
+
+	drm_dbg_core(dev, "%u\n", auth->magic);
+
+	return ret < 0 ? ret : 0;
+}
+
+int drm_authmagic(struct drm_device *dev, void *data,
+		  struct drm_file *file_priv)
+{
+	struct drm_auth *auth = data;
+	struct drm_file *file;
+
+	drm_dbg_core(dev, "%u\n", auth->magic);
+
+	mutex_lock(&dev->master_mutex);
+	file = idr_find(&file_priv->master->magic_map, auth->magic);
+	if (file) {
+		file->authenticated = 1;
+		idr_replace(&file_priv->master->magic_map, NULL, auth->magic);
+	}
+	mutex_unlock(&dev->master_mutex);
+
+	return file ? 0 : -EINVAL;
+}
+
+struct drm_master *drm_master_create(struct drm_device *dev)
+{
+	struct drm_master *master;
+
+	master = kzalloc(sizeof(*master), GFP_KERNEL);
+	if (!master)
+		return NULL;
+
+	kref_init(&master->refcount);
+	drm_master_legacy_init(master);
+	idr_init_base(&master->magic_map, 1);
+	master->dev = dev;
+
+	/* initialize the tree of output resource lessees */
+	INIT_LIST_HEAD(&master->lessees);
+	INIT_LIST_HEAD(&master->lessee_list);
+	idr_init(&master->leases);
+	idr_init_base(&master->lessee_idr, 1);
+
+	return master;
+}
+
+static void drm_set_master(struct drm_device *dev, struct drm_file *fpriv,
+			   bool new_master)
+{
+	dev->master = drm_master_get(fpriv->master);
+	if (dev->driver->master_set)
+		dev->driver->master_set(dev, fpriv, new_master);
+
+	fpriv->was_master = true;
+}
+
+static int drm_new_set_master(struct drm_device *dev, struct drm_file *fpriv)
+{
+	struct drm_master *old_master;
+	struct drm_master *new_master;
+
+	lockdep_assert_held_once(&dev->master_mutex);
+
+	WARN_ON(fpriv->is_master);
+	old_master = fpriv->master;
+	new_master = drm_master_create(dev);
+	if (!new_master)
+		return -ENOMEM;
+	spin_lock(&fpriv->master_lookup_lock);
+	fpriv->master = new_master;
+	spin_unlock(&fpriv->master_lookup_lock);
+
+	fpriv->is_master = 1;
+	fpriv->authenticated = 1;
+
+	drm_set_master(dev, fpriv, true);
+
+	if (old_master)
+		drm_master_put(&old_master);
+
+	return 0;
+}
+
+/*
+ * In the olden days the SET/DROP_MASTER ioctls used to return EACCES when
+ * CAP_SYS_ADMIN was not set. This was used to prevent rogue applications
+ * from becoming master and/or failing to release it.
+ *
+ * At the same time, the first client (for a given VT) is _always_ master.
+ * Thus in order for the ioctls to succeed, one had to _explicitly_ run the
+ * application as root or flip the setuid bit.
+ *
+ * If the CAP_SYS_ADMIN was missing, no other client could become master...
+ * EVER :-( Leading to a) the graphics session dying badly or b) a completely
+ * locked session.
+ *
+ *
+ * As some point systemd-logind was introduced to orchestrate and delegate
+ * master as applicable. It does so by opening the fd and passing it to users
+ * while in itself logind a) does the set/drop master per users' request and
+ * b)  * implicitly drops master on VT switch.
+ *
+ * Even though logind looks like the future, there are a few issues:
+ *  - some platforms don't have equivalent (Android, CrOS, some BSDs) so
+ * root is required _solely_ for SET/DROP MASTER.
+ *  - applications may not be updated to use it,
+ *  - any client which fails to drop master* can DoS the application using
+ * logind, to a varying degree.
+ *
+ * * Either due missing CAP_SYS_ADMIN or simply not calling DROP_MASTER.
+ *
+ *
+ * Here we implement the next best thing:
+ *  - ensure the logind style of fd passing works unchanged, and
+ *  - allow a client to drop/set master, iff it is/was master at a given point
+ * in time.
+ *
+ * Note: DROP_MASTER cannot be free for all, as an arbitrator user could:
+ *  - DoS/crash the arbitrator - details would be implementation specific
+ *  - open the node, become master implicitly and cause issues
+ *
+ * As a result this fixes the following when using root-less build w/o logind
+ * - startx
+ * - weston
+ * - various compositors based on wlroots
+ */
+static int
+drm_master_check_perm(struct drm_device *dev, struct drm_file *file_priv)
+{
+	if (file_priv->pid == task_pid(current) && file_priv->was_master)
+		return 0;
+
+	if (!capable(CAP_SYS_ADMIN))
+		return -EACCES;
+
+	return 0;
+}
+
+int drm_setmaster_ioctl(struct drm_device *dev, void *data,
+			struct drm_file *file_priv)
+{
+	int ret;
+
+	mutex_lock(&dev->master_mutex);
+
+	ret = drm_master_check_perm(dev, file_priv);
+	if (ret)
+		goto out_unlock;
+
+	if (drm_is_current_master_locked(file_priv))
+		goto out_unlock;
+
+	if (dev->master) {
+		ret = -EBUSY;
+		goto out_unlock;
+	}
+
+	if (!file_priv->master) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (!file_priv->is_master) {
+		ret = drm_new_set_master(dev, file_priv);
+		goto out_unlock;
+	}
+
+	if (file_priv->master->lessor != NULL) {
+		drm_dbg_lease(dev,
+			      "Attempt to set lessee %d as master\n",
+			      file_priv->master->lessee_id);
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	drm_set_master(dev, file_priv, false);
+out_unlock:
+	mutex_unlock(&dev->master_mutex);
+	return ret;
+}
+
+static void drm_drop_master(struct drm_device *dev,
+			    struct drm_file *fpriv)
+{
+	if (dev->driver->master_drop)
+		dev->driver->master_drop(dev, fpriv);
+	drm_master_put(&dev->master);
+}
+
+int drm_dropmaster_ioctl(struct drm_device *dev, void *data,
+			 struct drm_file *file_priv)
+{
+	int ret;
+
+	mutex_lock(&dev->master_mutex);
+
+	ret = drm_master_check_perm(dev, file_priv);
+	if (ret)
+		goto out_unlock;
+
+	if (!drm_is_current_master_locked(file_priv)) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (!dev->master) {
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	if (file_priv->master->lessor != NULL) {
+		drm_dbg_lease(dev,
+			      "Attempt to drop lessee %d as master\n",
+			      file_priv->master->lessee_id);
+		ret = -EINVAL;
+		goto out_unlock;
+	}
+
+	drm_drop_master(dev, file_priv);
+out_unlock:
+	mutex_unlock(&dev->master_mutex);
+	return ret;
+}
+
+int drm_master_open(struct drm_file *file_priv)
+{
+	struct drm_device *dev = file_priv->minor->dev;
+	int ret = 0;
+
+	/* if there is no current master make this fd it, but do not create
+	 * any master object for render clients
+	 */
+	mutex_lock(&dev->master_mutex);
+	if (!dev->master) {
+		ret = drm_new_set_master(dev, file_priv);
+	} else {
+		spin_lock(&file_priv->master_lookup_lock);
+		file_priv->master = drm_master_get(dev->master);
+		spin_unlock(&file_priv->master_lookup_lock);
+	}
+	mutex_unlock(&dev->master_mutex);
+
+	return ret;
+}
+
+void drm_master_release(struct drm_file *file_priv)
+{
+	struct drm_device *dev = file_priv->minor->dev;
+	struct drm_master *master;
+
+	mutex_lock(&dev->master_mutex);
+	master = file_priv->master;
+	if (file_priv->magic)
+		idr_remove(&file_priv->master->magic_map, file_priv->magic);
+
+	if (!drm_is_current_master_locked(file_priv))
+		goto out;
+
+	drm_legacy_lock_master_cleanup(dev, master);
+
+	if (dev->master == file_priv->master)
+		drm_drop_master(dev, file_priv);
+out:
+	if (drm_core_check_feature(dev, DRIVER_MODESET) && file_priv->is_master) {
+		/* Revoke any leases held by this or lessees, but only if
+		 * this is the "real" master
+		 */
+		drm_lease_revoke(master);
+	}
+
+	/* drop the master reference held by the file priv */
+	if (file_priv->master)
+		drm_master_put(&file_priv->master);
+	mutex_unlock(&dev->master_mutex);
+}
+
+/**
+ * drm_master_get - reference a master pointer
+ * @master: &struct drm_master
+ *
+ * Increments the reference count of @master and returns a pointer to @master.
+ */
+struct drm_master *drm_master_get(struct drm_master *master)
+{
+	kref_get(&master->refcount);
+	return master;
+}
+EXPORT_SYMBOL(drm_master_get);
+
+/**
+ * drm_file_get_master - reference &drm_file.master of @file_priv
+ * @file_priv: DRM file private
+ *
+ * Increments the reference count of @file_priv's &drm_file.master and returns
+ * the &drm_file.master. If @file_priv has no &drm_file.master, returns NULL.
+ *
+ * Master pointers returned from this function should be unreferenced using
+ * drm_master_put().
+ */
+struct drm_master *drm_file_get_master(struct drm_file *file_priv)
+{
+	struct drm_master *master = NULL;
+
+	spin_lock(&file_priv->master_lookup_lock);
+	if (!file_priv->master)
+		goto unlock;
+	master = drm_master_get(file_priv->master);
+
+unlock:
+	spin_unlock(&file_priv->master_lookup_lock);
+	return master;
+}
+EXPORT_SYMBOL(drm_file_get_master);
+
+static void drm_master_destroy(struct kref *kref)
+{
+	struct drm_master *master = container_of(kref, struct drm_master, refcount);
+	struct drm_device *dev = master->dev;
+
+	if (drm_core_check_feature(dev, DRIVER_MODESET))
+		drm_lease_destroy(master);
+
+	drm_legacy_master_rmmaps(dev, master);
+
+	idr_destroy(&master->magic_map);
+	idr_destroy(&master->leases);
+	idr_destroy(&master->lessee_idr);
+
+	kfree(master->unique);
+	kfree(master);
+}
+
+/**
+ * drm_master_put - unreference and clear a master pointer
+ * @master: pointer to a pointer of &struct drm_master
+ *
+ * This decrements the &drm_master behind @master and sets it to NULL.
+ */
+void drm_master_put(struct drm_master **master)
+{
+	kref_put(&(*master)->refcount, drm_master_destroy);
+	*master = NULL;
+}
+EXPORT_SYMBOL(drm_master_put);
+
+/* Used by drm_client and drm_fb_helper */
+bool drm_master_internal_acquire(struct drm_device *dev)
+{
+	mutex_lock(&dev->master_mutex);
+	if (dev->master) {
+		mutex_unlock(&dev->master_mutex);
+		return false;
+	}
+
+	return true;
+}
+EXPORT_SYMBOL(drm_master_internal_acquire);
+
+/* Used by drm_client and drm_fb_helper */
+void drm_master_internal_release(struct drm_device *dev)
+{
+	mutex_unlock(&dev->master_mutex);
+}
+EXPORT_SYMBOL(drm_master_internal_release);