Merge remote-tracking branch 'common/android-4.4-p' into lineage-18.1-caf-msm8998

* common/android-4.4-p:
  Linux 4.4.296
  xen/netback: don't queue unlimited number of packages
  xen/console: harden hvc_xen against event channel storms
  xen/netfront: harden netfront against event channel storms
  xen/blkfront: harden blkfront against event channel storms
  Input: touchscreen - avoid bitwise vs logical OR warning
  ARM: 8805/2: remove unneeded naked function usage
  net: lan78xx: Avoid unnecessary self assignment
  net: systemport: Add global locking for descriptor lifecycle
  timekeeping: Really make sure wall_to_monotonic isn't positive
  USB: serial: option: add Telit FN990 compositions
  PCI/MSI: Clear PCI_MSIX_FLAGS_MASKALL on error
  USB: gadget: bRequestType is a bitfield, not a enum
  igbvf: fix double free in `igbvf_probe`
  soc/tegra: fuse: Fix bitwise vs. logical OR warning
  nfsd: fix use-after-free due to delegation race
  dm btree remove: fix use after free in rebalance_children()
  recordmcount.pl: look for jgnop instruction as well as bcrl on s390
  mac80211: send ADDBA requests using the tid/queue of the aggregation session
  hwmon: (dell-smm) Fix warning on /proc/i8k creation error
  net: netlink: af_netlink: Prevent empty skb by adding a check on len.
  i2c: rk3x: Handle a spurious start completion interrupt flag
  parisc/agp: Annotate parisc agp init functions with __init
  nfc: fix segfault in nfc_genl_dump_devices_done
  FROMGIT: USB: gadget: bRequestType is a bitfield, not a enum
  Linux 4.4.295
  irqchip: nvic: Fix offset for Interrupt Priority Offsets
  irqchip/irq-gic-v3-its.c: Force synchronisation when issuing INVALL
  iio: accel: kxcjk-1013: Fix possible memory leak in probe and remove
  iio: itg3200: Call iio_trigger_notify_done() on error
  iio: ltr501: Don't return error code in trigger handler
  iio: mma8452: Fix trigger reference couting
  iio: stk3310: Don't return error code in interrupt handler
  usb: core: config: fix validation of wMaxPacketValue entries
  USB: gadget: zero allocate endpoint 0 buffers
  USB: gadget: detect too-big endpoint 0 requests
  net/qla3xxx: fix an error code in ql_adapter_up()
  net, neigh: clear whole pneigh_entry at alloc time
  net: fec: only clear interrupt of handling queue in fec_enet_rx_queue()
  net: altera: set a couple error code in probe()
  net: cdc_ncm: Allow for dwNtbOutMaxSize to be unset or zero
  block: fix ioprio_get(IOPRIO_WHO_PGRP) vs setuid(2)
  tracefs: Set all files to the same group ownership as the mount option
  signalfd: use wake_up_pollfree()
  binder: use wake_up_pollfree()
  wait: add wake_up_pollfree()
  libata: add horkage for ASMedia 1092
  can: pch_can: pch_can_rx_normal: fix use after free
  tracefs: Have new files inherit the ownership of their parent
  ALSA: pcm: oss: Handle missing errors in snd_pcm_oss_change_params*()
  ALSA: pcm: oss: Limit the period size to 16MB
  ALSA: pcm: oss: Fix negative period/buffer sizes
  ALSA: ctl: Fix copy of updated id with element read/write
  mm: bdi: initialize bdi_min_ratio when bdi is unregistered
  nfc: fix potential NULL pointer deref in nfc_genl_dump_ses_done
  can: sja1000: fix use after free in ems_pcmcia_add_card()
  HID: check for valid USB device for many HID drivers
  HID: wacom: fix problems when device is not a valid USB device
  HID: add USB_HID dependancy on some USB HID drivers
  HID: add USB_HID dependancy to hid-chicony
  HID: add USB_HID dependancy to hid-prodikeys
  HID: add hid_is_usb() function to make it simpler for USB detection
  HID: introduce hid_is_using_ll_driver
  UPSTREAM: USB: gadget: zero allocate endpoint 0 buffers
  UPSTREAM: USB: gadget: detect too-big endpoint 0 requests
  Linux 4.4.294
  serial: pl011: Add ACPI SBSA UART match id
  tty: serial: msm_serial: Deactivate RX DMA for polling support
  vgacon: Propagate console boot parameters before calling `vc_resize'
  parisc: Fix "make install" on newer debian releases
  siphash: use _unaligned version by default
  net: qlogic: qlcnic: Fix a NULL pointer dereference in qlcnic_83xx_add_rings()
  natsemi: xtensa: fix section mismatch warnings
  fget: check that the fd still exists after getting a ref to it
  fs: add fget_many() and fput_many()
  sata_fsl: fix warning in remove_proc_entry when rmmod sata_fsl
  sata_fsl: fix UAF in sata_fsl_port_stop when rmmod sata_fsl
  kprobes: Limit max data_size of the kretprobe instances
  net: ethernet: dec: tulip: de4x5: fix possible array overflows in type3_infoblock()
  net: tulip: de4x5: fix the problem that the array 'lp->phy[8]' may be out of bound
  scsi: iscsi: Unblock session then wake up error handler
  s390/setup: avoid using memblock_enforce_memory_limit
  platform/x86: thinkpad_acpi: Fix WWAN device disabled issue after S3 deep
  net: return correct error code
  hugetlb: take PMD sharing into account when flushing tlb/caches
  tty: hvc: replace BUG_ON() with negative return value
  xen/netfront: don't trust the backend response data blindly
  xen/netfront: disentangle tx_skb_freelist
  xen/netfront: don't read data from request on the ring page
  xen/netfront: read response from backend only once
  xen/blkfront: don't trust the backend response data blindly
  xen/blkfront: don't take local copy of a request from the ring page
  xen/blkfront: read response from backend only once
  xen: sync include/xen/interface/io/ring.h with Xen's newest version
  shm: extend forced shm destroy to support objects from several IPC nses
  fuse: release pipe buf after last use
  fuse: fix page stealing
  NFC: add NCI_UNREG flag to eliminate the race
  proc/vmcore: fix clearing user buffer by properly using clear_user()
  hugetlbfs: flush TLBs correctly after huge_pmd_unshare
  tracing: Check pid filtering when creating events
  tcp_cubic: fix spurious Hystart ACK train detections for not-cwnd-limited flows
  scsi: mpt3sas: Fix kernel panic during drive powercycle test
  ARM: socfpga: Fix crash with CONFIG_FORTIRY_SOURCE
  NFSv42: Don't fail clone() unless the OP_CLONE operation failed
  net: ieee802154: handle iftypes as u32
  ASoC: topology: Add missing rwsem around snd_ctl_remove() calls
  ARM: dts: BCM5301X: Add interrupt properties to GPIO node
  xen: detect uninitialized xenbus in xenbus_init
  xen: don't continue xenstore initialization in case of errors
  staging: rtl8192e: Fix use after free in _rtl92e_pci_disconnect()
  ALSA: ctxfi: Fix out-of-range access
  binder: fix test regression due to sender_euid change
  usb: hub: Fix locking issues with address0_mutex
  usb: hub: Fix usb enumeration issue due to address0 race
  USB: serial: option: add Fibocom FM101-GL variants
  USB: serial: option: add Telit LE910S1 0x9200 composition
  staging: ion: Prevent incorrect reference counting behavour

Change-Id: Iadf9f213915d2a02b27ceb3b2144eac827ade329

13 files changed, 216 insertions, 150 deletions

diff --git a/include/asm-generic/tlb.h b/include/asm-generic/tlb.h
index 9dbb739cafa0..5f794f6ec6c7 100644
--- a/include/asm-generic/tlb.h
+++ b/include/asm-generic/tlb.h
@@ -165,6 +165,13 @@ static inline void __tlb_reset_range(struct mmu_gather *tlb)
 #define tlb_end_vma	__tlb_end_vma
 #endif
 
+static inline void tlb_flush_pmd_range(struct mmu_gather *tlb,
+				unsigned long address, unsigned long size)
+{
+	tlb->start = min(tlb->start, address);
+	tlb->end = max(tlb->end, address + size);
+}
+
 #ifndef __tlb_remove_tlb_entry
 #define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
 #endif
diff --git a/include/linux/file.h b/include/linux/file.h
index f87d30882a24..67f0888abdde 100644
--- a/include/linux/file.h
+++ b/include/linux/file.h
@@ -12,6 +12,7 @@
 struct file;
 
 extern void fput(struct file *);
+extern void fput_many(struct file *, unsigned int);
 
 struct file_operations;
 struct vfsmount;
@@ -40,6 +41,7 @@ static inline void fdput(struct fd fd)
 }
 
 extern struct file *fget(unsigned int fd);
+extern struct file *fget_many(unsigned int fd, unsigned int refs);
 extern struct file *fget_raw(unsigned int fd);
 extern unsigned long __fdget(unsigned int fd);
 extern unsigned long __fdget_raw(unsigned int fd);
diff --git a/include/linux/fs.h b/include/linux/fs.h
index 80420810e217..077f8390fd81 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -961,7 +961,9 @@ static inline struct file *get_file(struct file *f)
 	atomic_long_inc(&f->f_count);
 	return f;
 }
-#define get_file_rcu(x) atomic_long_inc_not_zero(&(x)->f_count)
+#define get_file_rcu_many(x, cnt)	\
+	atomic_long_add_unless(&(x)->f_count, (cnt), 0)
+#define get_file_rcu(x) get_file_rcu_many((x), 1)
 #define fput_atomic(x)	atomic_long_add_unless(&(x)->f_count, -1, 1)
 #define file_count(x)	atomic_long_read(&(x)->f_count)
 
diff --git a/include/linux/hid.h b/include/linux/hid.h
index 51e1dbe8c387..3b0ad4479725 100644
--- a/include/linux/hid.h
+++ b/include/linux/hid.h
@@ -763,6 +763,22 @@ struct hid_ll_driver {
 	int (*idle)(struct hid_device *hdev, int report, int idle, int reqtype);
 };
 
+extern struct hid_ll_driver i2c_hid_ll_driver;
+extern struct hid_ll_driver hidp_hid_driver;
+extern struct hid_ll_driver uhid_hid_driver;
+extern struct hid_ll_driver usb_hid_driver;
+
+static inline bool hid_is_using_ll_driver(struct hid_device *hdev,
+		struct hid_ll_driver *driver)
+{
+	return hdev->ll_driver == driver;
+}
+
+static inline bool hid_is_usb(struct hid_device *hdev)
+{
+	return hid_is_using_ll_driver(hdev, &usb_hid_driver);
+}
+
 #define	PM_HINT_FULLON	1<<5
 #define PM_HINT_NORMAL	1<<1
 
diff --git a/include/linux/ipc_namespace.h b/include/linux/ipc_namespace.h
index 1eee6bcfcf76..cf1a1c126e89 100644
--- a/include/linux/ipc_namespace.h
+++ b/include/linux/ipc_namespace.h
@@ -123,6 +123,16 @@ static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 	return ns;
 }
 
+static inline struct ipc_namespace *get_ipc_ns_not_zero(struct ipc_namespace *ns)
+{
+	if (ns) {
+		if (atomic_inc_not_zero(&ns->count))
+			return ns;
+	}
+
+	return NULL;
+}
+
 extern void put_ipc_ns(struct ipc_namespace *ns);
 #else
 static inline struct ipc_namespace *copy_ipcs(unsigned long flags,
@@ -139,6 +149,11 @@ static inline struct ipc_namespace *get_ipc_ns(struct ipc_namespace *ns)
 	return ns;
 }
 
+static inline struct ipc_namespace *get_ipc_ns_not_zero(struct ipc_namespace *ns)
+{
+	return ns;
+}
+
 static inline void put_ipc_ns(struct ipc_namespace *ns)
 {
 }
diff --git a/include/linux/kprobes.h b/include/linux/kprobes.h
index 4db62045f01a..006ef813959b 100644
--- a/include/linux/kprobes.h
+++ b/include/linux/kprobes.h
@@ -192,6 +192,8 @@ struct kretprobe {
 	raw_spinlock_t lock;
 };
 
+#define KRETPROBE_MAX_DATA_SIZE	4096
+
 struct kretprobe_instance {
 	struct hlist_node hlist;
 	struct kretprobe *rp;
diff --git a/include/linux/sched.h b/include/linux/sched.h
index 6a800ecef83a..70c1f7f9e4fa 100644
--- a/include/linux/sched.h
+++ b/include/linux/sched.h
@@ -3194,7 +3194,7 @@ static inline int thread_group_empty(struct task_struct *p)
  * Protects ->fs, ->files, ->mm, ->group_info, ->comm, keyring
  * subscriptions and synchronises with wait4().  Also used in procfs.  Also
  * pins the final release of task.io_context.  Also protects ->cpuset and
- * ->cgroup.subsys[]. And ->vfork_done.
+ * ->cgroup.subsys[]. And ->vfork_done. And ->sysvshm.shm_clist.
  *
  * Nests both inside and outside of read_lock(&tasklist_lock).
  * It must not be nested with write_lock_irq(&tasklist_lock),
diff --git a/include/linux/shm.h b/include/linux/shm.h
index 6fb801686ad6..fbb74824f0df 100644
--- a/include/linux/shm.h
+++ b/include/linux/shm.h
@@ -19,9 +19,18 @@ struct shmid_kernel /* private to the kernel */
 	pid_t			shm_lprid;
 	struct user_struct	*mlock_user;
 
-	/* The task created the shm object.  NULL if the task is dead. */
+	/*
+	 * The task created the shm object, for
+	 * task_lock(shp->shm_creator)
+	 */
 	struct task_struct	*shm_creator;
-	struct list_head	shm_clist;	/* list by creator */
+
+	/*
+	 * List by creator. task_lock(->shm_creator) required for read/write.
+	 * If list_empty(), then the creator is dead already.
+	 */
+	struct list_head	shm_clist;
+	struct ipc_namespace	*ns;
 };
 
 /* shm_mode upper byte flags */
diff --git a/include/linux/siphash.h b/include/linux/siphash.h
index bf21591a9e5e..0cda61855d90 100644
--- a/include/linux/siphash.h
+++ b/include/linux/siphash.h
@@ -27,9 +27,7 @@ static inline bool siphash_key_is_zero(const siphash_key_t *key)
 }
 
 u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key);
-#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key);
-#endif
 
 u64 siphash_1u64(const u64 a, const siphash_key_t *key);
 u64 siphash_2u64(const u64 a, const u64 b, const siphash_key_t *key);
@@ -82,10 +80,9 @@ static inline u64 ___siphash_aligned(const __le64 *data, size_t len,
 static inline u64 siphash(const void *data, size_t len,
 			  const siphash_key_t *key)
 {
-#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-	if (!IS_ALIGNED((unsigned long)data, SIPHASH_ALIGNMENT))
+	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
+	    !IS_ALIGNED((unsigned long)data, SIPHASH_ALIGNMENT))
 		return __siphash_unaligned(data, len, key);
-#endif
 	return ___siphash_aligned(data, len, key);
 }
 
@@ -96,10 +93,8 @@ typedef struct {
 
 u32 __hsiphash_aligned(const void *data, size_t len,
 		       const hsiphash_key_t *key);
-#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
 u32 __hsiphash_unaligned(const void *data, size_t len,
 			 const hsiphash_key_t *key);
-#endif
 
 u32 hsiphash_1u32(const u32 a, const hsiphash_key_t *key);
 u32 hsiphash_2u32(const u32 a, const u32 b, const hsiphash_key_t *key);
@@ -135,10 +130,9 @@ static inline u32 ___hsiphash_aligned(const __le32 *data, size_t len,
 static inline u32 hsiphash(const void *data, size_t len,
 			   const hsiphash_key_t *key)
 {
-#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
-	if (!IS_ALIGNED((unsigned long)data, HSIPHASH_ALIGNMENT))
+	if (IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS) ||
+	    !IS_ALIGNED((unsigned long)data, HSIPHASH_ALIGNMENT))
 		return __hsiphash_unaligned(data, len, key);
-#endif
 	return ___hsiphash_aligned(data, len, key);
 }
 
diff --git a/include/linux/wait.h b/include/linux/wait.h
index 513b36f04dfd..419b5b2bf547 100644
--- a/include/linux/wait.h
+++ b/include/linux/wait.h
@@ -151,6 +151,7 @@ void __wake_up_locked_key(wait_queue_head_t *q, unsigned int mode, void *key);
 void __wake_up_sync_key(wait_queue_head_t *q, unsigned int mode, int nr, void *key);
 void __wake_up_locked(wait_queue_head_t *q, unsigned int mode, int nr);
 void __wake_up_sync(wait_queue_head_t *q, unsigned int mode, int nr);
+void __wake_up_pollfree(wait_queue_head_t *wq_head);
 void __wake_up_bit(wait_queue_head_t *, void *, int);
 int __wait_on_bit(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
 int __wait_on_bit_lock(wait_queue_head_t *, struct wait_bit_queue *, wait_bit_action_f *, unsigned);
@@ -185,6 +186,31 @@ wait_queue_head_t *bit_waitqueue(void *, int);
 #define wake_up_interruptible_sync_poll(x, m)				\
 	__wake_up_sync_key((x), TASK_INTERRUPTIBLE, 1, (void *) (m))
 
+/**
+ * wake_up_pollfree - signal that a polled waitqueue is going away
+ * @wq_head: the wait queue head
+ *
+ * In the very rare cases where a ->poll() implementation uses a waitqueue whose
+ * lifetime is tied to a task rather than to the 'struct file' being polled,
+ * this function must be called before the waitqueue is freed so that
+ * non-blocking polls (e.g. epoll) are notified that the queue is going away.
+ *
+ * The caller must also RCU-delay the freeing of the wait_queue_head, e.g. via
+ * an explicit synchronize_rcu() or call_rcu(), or via SLAB_DESTROY_BY_RCU.
+ */
+static inline void wake_up_pollfree(wait_queue_head_t *wq_head)
+{
+	/*
+	 * For performance reasons, we don't always take the queue lock here.
+	 * Therefore, we might race with someone removing the last entry from
+	 * the queue, and proceed while they still hold the queue lock.
+	 * However, rcu_read_lock() is required to be held in such cases, so we
+	 * can safely proceed with an RCU-delayed free.
+	 */
+	if (waitqueue_active(wq_head))
+		__wake_up_pollfree(wq_head);
+}
+
 #define ___wait_cond_timeout(condition)					\
 ({									\
 	bool __cond = (condition);					\
diff --git a/include/net/nfc/nci_core.h b/include/net/nfc/nci_core.h
index f0e951292de8..53bd3c952ed4 100644
--- a/include/net/nfc/nci_core.h
+++ b/include/net/nfc/nci_core.h
@@ -42,6 +42,7 @@ enum nci_flag {
 	NCI_UP,
 	NCI_DATA_EXCHANGE,
 	NCI_DATA_EXCHANGE_TO,
+	NCI_UNREG,
 };
 
 /* NCI device states */
diff --git a/include/net/nl802154.h b/include/net/nl802154.h
index 32cb3e591e07..53f140fc1983 100644
--- a/include/net/nl802154.h
+++ b/include/net/nl802154.h
@@ -19,6 +19,8 @@
  *
  */
 
+#include <linux/types.h>
+
 #define NL802154_GENL_NAME "nl802154"
 
 enum nl802154_commands {
@@ -143,10 +145,9 @@ enum nl802154_attrs {
 };
 
 enum nl802154_iftype {
-	/* for backwards compatibility TODO */
-	NL802154_IFTYPE_UNSPEC = -1,
+	NL802154_IFTYPE_UNSPEC = (~(__u32)0),
 
-	NL802154_IFTYPE_NODE,
+	NL802154_IFTYPE_NODE = 0,
 	NL802154_IFTYPE_MONITOR,
 	NL802154_IFTYPE_COORD,
 
diff --git a/include/xen/interface/io/ring.h b/include/xen/interface/io/ring.h
index 7dc685b4057d..4076d1c407d8 100644
--- a/include/xen/interface/io/ring.h
+++ b/include/xen/interface/io/ring.h
@@ -24,82 +24,79 @@ typedef unsigned int RING_IDX;
  * A ring contains as many entries as will fit, rounded down to the nearest
  * power of two (so we can mask with (size-1) to loop around).
  */
-#define __CONST_RING_SIZE(_s, _sz)				\
-	(__RD32(((_sz) - offsetof(struct _s##_sring, ring)) /	\
-		sizeof(((struct _s##_sring *)0)->ring[0])))
-
+#define __CONST_RING_SIZE(_s, _sz) \
+    (__RD32(((_sz) - offsetof(struct _s##_sring, ring)) / \
+	    sizeof(((struct _s##_sring *)0)->ring[0])))
 /*
  * The same for passing in an actual pointer instead of a name tag.
  */
-#define __RING_SIZE(_s, _sz)						\
-	(__RD32(((_sz) - (long)&(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
+#define __RING_SIZE(_s, _sz) \
+    (__RD32(((_sz) - (long)(_s)->ring + (long)(_s)) / sizeof((_s)->ring[0])))
 
 /*
  * Macros to make the correct C datatypes for a new kind of ring.
  *
  * To make a new ring datatype, you need to have two message structures,
- * let's say struct request, and struct response already defined.
+ * let's say request_t, and response_t already defined.
  *
  * In a header where you want the ring datatype declared, you then do:
  *
- *     DEFINE_RING_TYPES(mytag, struct request, struct response);
+ *     DEFINE_RING_TYPES(mytag, request_t, response_t);
  *
  * These expand out to give you a set of types, as you can see below.
  * The most important of these are:
  *
- *     struct mytag_sring      - The shared ring.
- *     struct mytag_front_ring - The 'front' half of the ring.
- *     struct mytag_back_ring  - The 'back' half of the ring.
+ *     mytag_sring_t      - The shared ring.
+ *     mytag_front_ring_t - The 'front' half of the ring.
+ *     mytag_back_ring_t  - The 'back' half of the ring.
  *
  * To initialize a ring in your code you need to know the location and size
  * of the shared memory area (PAGE_SIZE, for instance). To initialise
  * the front half:
  *
- *     struct mytag_front_ring front_ring;
- *     SHARED_RING_INIT((struct mytag_sring *)shared_page);
- *     FRONT_RING_INIT(&front_ring, (struct mytag_sring *)shared_page,
- *		       PAGE_SIZE);
+ *     mytag_front_ring_t front_ring;
+ *     SHARED_RING_INIT((mytag_sring_t *)shared_page);
+ *     FRONT_RING_INIT(&front_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
  *
  * Initializing the back follows similarly (note that only the front
  * initializes the shared ring):
  *
- *     struct mytag_back_ring back_ring;
- *     BACK_RING_INIT(&back_ring, (struct mytag_sring *)shared_page,
- *		      PAGE_SIZE);
+ *     mytag_back_ring_t back_ring;
+ *     BACK_RING_INIT(&back_ring, (mytag_sring_t *)shared_page, PAGE_SIZE);
  */
 
-#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t)			\
-									\
-/* Shared ring entry */							\
-union __name##_sring_entry {						\
-    __req_t req;							\
-    __rsp_t rsp;							\
-};									\
-									\
-/* Shared ring page */							\
-struct __name##_sring {							\
-    RING_IDX req_prod, req_event;					\
-    RING_IDX rsp_prod, rsp_event;					\
-    uint8_t  pad[48];							\
-    union __name##_sring_entry ring[1]; /* variable-length */		\
-};									\
-									\
-/* "Front" end's private variables */					\
-struct __name##_front_ring {						\
-    RING_IDX req_prod_pvt;						\
-    RING_IDX rsp_cons;							\
-    unsigned int nr_ents;						\
-    struct __name##_sring *sring;					\
-};									\
-									\
-/* "Back" end's private variables */					\
-struct __name##_back_ring {						\
-    RING_IDX rsp_prod_pvt;						\
-    RING_IDX req_cons;							\
-    unsigned int nr_ents;						\
-    struct __name##_sring *sring;					\
-};
-
+#define DEFINE_RING_TYPES(__name, __req_t, __rsp_t)                     \
+                                                                        \
+/* Shared ring entry */                                                 \
+union __name##_sring_entry {                                            \
+    __req_t req;                                                        \
+    __rsp_t rsp;                                                        \
+};                                                                      \
+                                                                        \
+/* Shared ring page */                                                  \
+struct __name##_sring {                                                 \
+    RING_IDX req_prod, req_event;                                       \
+    RING_IDX rsp_prod, rsp_event;                                       \
+    uint8_t __pad[48];                                                  \
+    union __name##_sring_entry ring[1]; /* variable-length */           \
+};                                                                      \
+                                                                        \
+/* "Front" end's private variables */                                   \
+struct __name##_front_ring {                                            \
+    RING_IDX req_prod_pvt;                                              \
+    RING_IDX rsp_cons;                                                  \
+    unsigned int nr_ents;                                               \
+    struct __name##_sring *sring;                                       \
+};                                                                      \
+                                                                        \
+/* "Back" end's private variables */                                    \
+struct __name##_back_ring {                                             \
+    RING_IDX rsp_prod_pvt;                                              \
+    RING_IDX req_cons;                                                  \
+    unsigned int nr_ents;                                               \
+    struct __name##_sring *sring;                                       \
+};                                                                      \
+                                                                        \
 /*
  * Macros for manipulating rings.
  *
@@ -116,105 +113,99 @@ struct __name##_back_ring {						\
  */
 
 /* Initialising empty rings */
-#define SHARED_RING_INIT(_s) do {					\
-    (_s)->req_prod  = (_s)->rsp_prod  = 0;				\
-    (_s)->req_event = (_s)->rsp_event = 1;				\
-    memset((_s)->pad, 0, sizeof((_s)->pad));				\
+#define SHARED_RING_INIT(_s) do {                                       \
+    (_s)->req_prod  = (_s)->rsp_prod  = 0;                              \
+    (_s)->req_event = (_s)->rsp_event = 1;                              \
+    (void)memset((_s)->__pad, 0, sizeof((_s)->__pad));                  \
 } while(0)
 
-#define FRONT_RING_INIT(_r, _s, __size) do {				\
-    (_r)->req_prod_pvt = 0;						\
-    (_r)->rsp_cons = 0;							\
-    (_r)->nr_ents = __RING_SIZE(_s, __size);				\
-    (_r)->sring = (_s);							\
+#define FRONT_RING_ATTACH(_r, _s, _i, __size) do {                      \
+    (_r)->req_prod_pvt = (_i);                                          \
+    (_r)->rsp_cons = (_i);                                              \
+    (_r)->nr_ents = __RING_SIZE(_s, __size);                            \
+    (_r)->sring = (_s);                                                 \
 } while (0)
 
-#define BACK_RING_INIT(_r, _s, __size) do {				\
-    (_r)->rsp_prod_pvt = 0;						\
-    (_r)->req_cons = 0;							\
-    (_r)->nr_ents = __RING_SIZE(_s, __size);				\
-    (_r)->sring = (_s);							\
-} while (0)
+#define FRONT_RING_INIT(_r, _s, __size) FRONT_RING_ATTACH(_r, _s, 0, __size)
 
-/* Initialize to existing shared indexes -- for recovery */
-#define FRONT_RING_ATTACH(_r, _s, __size) do {				\
-    (_r)->sring = (_s);							\
-    (_r)->req_prod_pvt = (_s)->req_prod;				\
-    (_r)->rsp_cons = (_s)->rsp_prod;					\
-    (_r)->nr_ents = __RING_SIZE(_s, __size);				\
+#define BACK_RING_ATTACH(_r, _s, _i, __size) do {                       \
+    (_r)->rsp_prod_pvt = (_i);                                          \
+    (_r)->req_cons = (_i);                                              \
+    (_r)->nr_ents = __RING_SIZE(_s, __size);                            \
+    (_r)->sring = (_s);                                                 \
 } while (0)
 
-#define BACK_RING_ATTACH(_r, _s, __size) do {				\
-    (_r)->sring = (_s);							\
-    (_r)->rsp_prod_pvt = (_s)->rsp_prod;				\
-    (_r)->req_cons = (_s)->req_prod;					\
-    (_r)->nr_ents = __RING_SIZE(_s, __size);				\
-} while (0)
+#define BACK_RING_INIT(_r, _s, __size) BACK_RING_ATTACH(_r, _s, 0, __size)
 
 /* How big is this ring? */
-#define RING_SIZE(_r)							\
+#define RING_SIZE(_r)                                                   \
     ((_r)->nr_ents)
 
 /* Number of free requests (for use on front side only). */
-#define RING_FREE_REQUESTS(_r)						\
+#define RING_FREE_REQUESTS(_r)                                          \
     (RING_SIZE(_r) - ((_r)->req_prod_pvt - (_r)->rsp_cons))
 
 /* Test if there is an empty slot available on the front ring.
  * (This is only meaningful from the front. )
  */
-#define RING_FULL(_r)							\
+#define RING_FULL(_r)                                                   \
     (RING_FREE_REQUESTS(_r) == 0)
 
 /* Test if there are outstanding messages to be processed on a ring. */
-#define RING_HAS_UNCONSUMED_RESPONSES(_r)				\
+#define RING_HAS_UNCONSUMED_RESPONSES(_r)                               \
     ((_r)->sring->rsp_prod - (_r)->rsp_cons)
 
-#define RING_HAS_UNCONSUMED_REQUESTS(_r)				\
-    ({									\
-	unsigned int req = (_r)->sring->req_prod - (_r)->req_cons;	\
-	unsigned int rsp = RING_SIZE(_r) -				\
-			   ((_r)->req_cons - (_r)->rsp_prod_pvt);	\
-	req < rsp ? req : rsp;						\
-    })
+#define RING_HAS_UNCONSUMED_REQUESTS(_r) ({                             \
+    unsigned int req = (_r)->sring->req_prod - (_r)->req_cons;          \
+    unsigned int rsp = RING_SIZE(_r) -                                  \
+        ((_r)->req_cons - (_r)->rsp_prod_pvt);                          \
+    req < rsp ? req : rsp;                                              \
+})
 
 /* Direct access to individual ring elements, by index. */
-#define RING_GET_REQUEST(_r, _idx)					\
+#define RING_GET_REQUEST(_r, _idx)                                      \
     (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].req))
 
+#define RING_GET_RESPONSE(_r, _idx)                                     \
+    (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
+
 /*
- * Get a local copy of a request.
+ * Get a local copy of a request/response.
  *
- * Use this in preference to RING_GET_REQUEST() so all processing is
+ * Use this in preference to RING_GET_{REQUEST,RESPONSE}() so all processing is
  * done on a local copy that cannot be modified by the other end.
  *
  * Note that https://gcc.gnu.org/bugzilla/show_bug.cgi?id=58145 may cause this
- * to be ineffective where _req is a struct which consists of only bitfields.
+ * to be ineffective where dest is a struct which consists of only bitfields.
  */
-#define RING_COPY_REQUEST(_r, _idx, _req) do {				\
-	/* Use volatile to force the copy into _req. */			\
-	*(_req) = *(volatile typeof(_req))RING_GET_REQUEST(_r, _idx);	\
+#define RING_COPY_(type, r, idx, dest) do {				\
+	/* Use volatile to force the copy into dest. */			\
+	*(dest) = *(volatile typeof(dest))RING_GET_##type(r, idx);	\
 } while (0)
 
-#define RING_GET_RESPONSE(_r, _idx)					\
-    (&((_r)->sring->ring[((_idx) & (RING_SIZE(_r) - 1))].rsp))
+#define RING_COPY_REQUEST(r, idx, req)  RING_COPY_(REQUEST, r, idx, req)
+#define RING_COPY_RESPONSE(r, idx, rsp) RING_COPY_(RESPONSE, r, idx, rsp)
 
 /* Loop termination condition: Would the specified index overflow the ring? */
-#define RING_REQUEST_CONS_OVERFLOW(_r, _cons)				\
+#define RING_REQUEST_CONS_OVERFLOW(_r, _cons)                           \
     (((_cons) - (_r)->rsp_prod_pvt) >= RING_SIZE(_r))
 
 /* Ill-behaved frontend determination: Can there be this many requests? */
-#define RING_REQUEST_PROD_OVERFLOW(_r, _prod)               \
+#define RING_REQUEST_PROD_OVERFLOW(_r, _prod)                           \
     (((_prod) - (_r)->rsp_prod_pvt) > RING_SIZE(_r))
 
+/* Ill-behaved backend determination: Can there be this many responses? */
+#define RING_RESPONSE_PROD_OVERFLOW(_r, _prod)                          \
+    (((_prod) - (_r)->rsp_cons) > RING_SIZE(_r))
 
-#define RING_PUSH_REQUESTS(_r) do {					\
-    wmb(); /* back sees requests /before/ updated producer index */	\
-    (_r)->sring->req_prod = (_r)->req_prod_pvt;				\
+#define RING_PUSH_REQUESTS(_r) do {                                    \
+    wmb(); /* back sees requests /before/ updated producer index */    \
+    (_r)->sring->req_prod = (_r)->req_prod_pvt;                        \
 } while (0)
 
-#define RING_PUSH_RESPONSES(_r) do {					\
-    wmb(); /* front sees responses /before/ updated producer index */	\
-    (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt;				\
+#define RING_PUSH_RESPONSES(_r) do {                                   \
+    wmb(); /* front sees resps /before/ updated producer index */      \
+    (_r)->sring->rsp_prod = (_r)->rsp_prod_pvt;                        \
 } while (0)
 
 /*
@@ -247,40 +238,40 @@ struct __name##_back_ring {						\
  *  field appropriately.
  */
 
-#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do {		\
-    RING_IDX __old = (_r)->sring->req_prod;				\
-    RING_IDX __new = (_r)->req_prod_pvt;				\
-    wmb(); /* back sees requests /before/ updated producer index */	\
-    (_r)->sring->req_prod = __new;					\
-    mb(); /* back sees new requests /before/ we check req_event */	\
-    (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) <		\
-		 (RING_IDX)(__new - __old));				\
+#define RING_PUSH_REQUESTS_AND_CHECK_NOTIFY(_r, _notify) do {          \
+    RING_IDX __old = (_r)->sring->req_prod;                            \
+    RING_IDX __new = (_r)->req_prod_pvt;                               \
+    wmb(); /* back sees requests /before/ updated producer index */    \
+    (_r)->sring->req_prod = __new;                                     \
+    mb(); /* back sees new requests /before/ we check req_event */     \
+    (_notify) = ((RING_IDX)(__new - (_r)->sring->req_event) <          \
+                 (RING_IDX)(__new - __old));                           \
 } while (0)
 
-#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do {		\
-    RING_IDX __old = (_r)->sring->rsp_prod;				\
-    RING_IDX __new = (_r)->rsp_prod_pvt;				\
-    wmb(); /* front sees responses /before/ updated producer index */	\
-    (_r)->sring->rsp_prod = __new;					\
-    mb(); /* front sees new responses /before/ we check rsp_event */	\
-    (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) <		\
-		 (RING_IDX)(__new - __old));				\
+#define RING_PUSH_RESPONSES_AND_CHECK_NOTIFY(_r, _notify) do {         \
+    RING_IDX __old = (_r)->sring->rsp_prod;                            \
+    RING_IDX __new = (_r)->rsp_prod_pvt;                               \
+    wmb(); /* front sees resps /before/ updated producer index */      \
+    (_r)->sring->rsp_prod = __new;                                     \
+    mb(); /* front sees new resps /before/ we check rsp_event */       \
+    (_notify) = ((RING_IDX)(__new - (_r)->sring->rsp_event) <          \
+                 (RING_IDX)(__new - __old));                           \
 } while (0)
 
-#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do {		\
-    (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r);			\
-    if (_work_to_do) break;						\
-    (_r)->sring->req_event = (_r)->req_cons + 1;			\
-    mb();								\
-    (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r);			\
+#define RING_FINAL_CHECK_FOR_REQUESTS(_r, _work_to_do) do {            \
+    (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r);                  \
+    if (_work_to_do) break;                                            \
+    (_r)->sring->req_event = (_r)->req_cons + 1;                       \
+    mb();                                                              \
+    (_work_to_do) = RING_HAS_UNCONSUMED_REQUESTS(_r);                  \
 } while (0)
 
-#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do {		\
-    (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r);			\
-    if (_work_to_do) break;						\
-    (_r)->sring->rsp_event = (_r)->rsp_cons + 1;			\
-    mb();								\
-    (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r);			\
+#define RING_FINAL_CHECK_FOR_RESPONSES(_r, _work_to_do) do {           \
+    (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r);                 \
+    if (_work_to_do) break;                                            \
+    (_r)->sring->rsp_event = (_r)->rsp_cons + 1;                       \
+    mb();                                                              \
+    (_work_to_do) = RING_HAS_UNCONSUMED_RESPONSES(_r);                 \
 } while (0)
 
 #endif /* __XEN_PUBLIC_IO_RING_H__ */