Merge 4.4.224 into android-4.4-p

Changes in 4.4.224
	USB: serial: qcserial: Add DW5816e support
	Revert "net: phy: Avoid polling PHY with PHY_IGNORE_INTERRUPTS"
	dp83640: reverse arguments to list_add_tail
	net/mlx4_core: Fix use of ENOSPC around mlx4_counter_alloc()
	sch_sfq: validate silly quantum values
	sch_choke: avoid potential panic in choke_reset()
	Revert "ACPI / video: Add force_native quirk for HP Pavilion dv6"
	enic: do not overwrite error code
	ipv6: fix cleanup ordering for ip6_mr failure
	binfmt_elf: move brk out of mmap when doing direct loader exec
	x86/apm: Don't access __preempt_count with zeroed fs
	Revert "IB/ipoib: Update broadcast object if PKey value was changed in index 0"
	USB: uas: add quirk for LaCie 2Big Quadra
	USB: serial: garmin_gps: add sanity checking for data length
	batman-adv: fix batadv_nc_random_weight_tq
	scripts/decodecode: fix trapping instruction formatting
	phy: micrel: Ensure interrupts are reenabled on resume
	binfmt_elf: Do not move brk for INTERP-less ET_EXEC
	ext4: add cond_resched() to ext4_protect_reserved_inode
	net: ipv6: add net argument to ip6_dst_lookup_flow
	net: ipv6_stub: use ip6_dst_lookup_flow instead of ip6_dst_lookup
	blktrace: Fix potential deadlock between delete & sysfs ops
	blktrace: fix unlocked access to init/start-stop/teardown
	blktrace: fix trace mutex deadlock
	blktrace: Protect q->blk_trace with RCU
	blktrace: fix dereference after null check
	ptp: do not explicitly set drvdata in ptp_clock_register()
	ptp: use is_visible method to hide unused attributes
	ptp: create "pins" together with the rest of attributes
	chardev: add helper function to register char devs with a struct device
	ptp: Fix pass zero to ERR_PTR() in ptp_clock_register
	ptp: fix the race between the release of ptp_clock and cdev
	ptp: free ptp device pin descriptors properly
	net: handle no dst on skb in icmp6_send
	net/sonic: Fix a resource leak in an error handling path in 'jazz_sonic_probe()'
	net: moxa: Fix a potential double 'free_irq()'
	drop_monitor: work around gcc-10 stringop-overflow warning
	scsi: sg: add sg_remove_request in sg_write
	spi: spi-dw: Add lock protect dw_spi rx/tx to prevent concurrent calls
	cifs: Check for timeout on Negotiate stage
	cifs: Fix a race condition with cifs_echo_request
	dmaengine: pch_dma.c: Avoid data race between probe and irq handler
	dmaengine: mmp_tdma: Reset channel error on release
	drm/qxl: lost qxl_bo_kunmap_atomic_page in qxl_image_init_helper()
	ipc/util.c: sysvipc_find_ipc() incorrectly updates position index
	net: openvswitch: fix csum updates for MPLS actions
	gre: do not keep the GRE header around in collect medata mode
	mm/memory_hotplug.c: fix overflow in test_pages_in_a_zone()
	scsi: qla2xxx: Avoid double completion of abort command
	i40e: avoid NVM acquire deadlock during NVM update
	net/mlx5: Fix driver load error flow when firmware is stuck
	netfilter: conntrack: avoid gcc-10 zero-length-bounds warning
	IB/mlx4: Test return value of calls to ib_get_cached_pkey
	pnp: Use list_for_each_entry() instead of open coding
	gcc-10 warnings: fix low-hanging fruit
	kbuild: compute false-positive -Wmaybe-uninitialized cases in Kconfig
	Stop the ad-hoc games with -Wno-maybe-initialized
	gcc-10: disable 'zero-length-bounds' warning for now
	gcc-10: disable 'array-bounds' warning for now
	gcc-10: disable 'stringop-overflow' warning for now
	gcc-10: disable 'restrict' warning for now
	block: defer timeouts to a workqueue
	blk-mq: Allow timeouts to run while queue is freezing
	blk-mq: sync the update nr_hw_queues with blk_mq_queue_tag_busy_iter
	blk-mq: Allow blocking queue tag iter callbacks
	x86/paravirt: Remove the unused irq_enable_sysexit pv op
	gcc-10: avoid shadowing standard library 'free()' in crypto
	net: fix a potential recursive NETDEV_FEAT_CHANGE
	net: ipv4: really enforce backoff for redirects
	netlabel: cope with NULL catmap
	ALSA: hda/realtek - Limit int mic boost for Thinkpad T530
	ALSA: rawmidi: Fix racy buffer resize under concurrent accesses
	ALSA: rawmidi: Initialize allocated buffers
	USB: gadget: fix illegal array access in binding with UDC
	ARM: dts: imx27-phytec-phycard-s-rdk: Fix the I2C1 pinctrl entries
	x86: Fix early boot crash on gcc-10, third try
	exec: Move would_dump into flush_old_exec
	usb: gadget: net2272: Fix a memory leak in an error handling path in 'net2272_plat_probe()'
	usb: gadget: audio: Fix a missing error return value in audio_bind()
	usb: gadget: legacy: fix error return code in gncm_bind()
	usb: gadget: legacy: fix error return code in cdc_bind()
	Revert "ALSA: hda/realtek: Fix pop noise on ALC225"
	ARM: dts: r8a7740: Add missing extal2 to CPG node
	KVM: x86: Fix off-by-one error in kvm_vcpu_ioctl_x86_setup_mce
	Makefile: disallow data races on gcc-10 as well
	scsi: iscsi: Fix a potential deadlock in the timeout handler
	Linux 4.4.224

Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I384313d39dead8b0babb144803269033f4aacc53

1 files changed, 86 insertions, 0 deletions

diff --git a/fs/char_dev.c b/fs/char_dev.c
index f1f3bb812799..9154a2d7b195 100644
--- a/fs/char_dev.c
+++ b/fs/char_dev.c
@@ -472,6 +472,85 @@ int cdev_add(struct cdev *p, dev_t dev, unsigned count)
 	return 0;
 }
 
+/**
+ * cdev_set_parent() - set the parent kobject for a char device
+ * @p: the cdev structure
+ * @kobj: the kobject to take a reference to
+ *
+ * cdev_set_parent() sets a parent kobject which will be referenced
+ * appropriately so the parent is not freed before the cdev. This
+ * should be called before cdev_add.
+ */
+void cdev_set_parent(struct cdev *p, struct kobject *kobj)
+{
+	WARN_ON(!kobj->state_initialized);
+	p->kobj.parent = kobj;
+}
+
+/**
+ * cdev_device_add() - add a char device and it's corresponding
+ *	struct device, linkink
+ * @dev: the device structure
+ * @cdev: the cdev structure
+ *
+ * cdev_device_add() adds the char device represented by @cdev to the system,
+ * just as cdev_add does. It then adds @dev to the system using device_add
+ * The dev_t for the char device will be taken from the struct device which
+ * needs to be initialized first. This helper function correctly takes a
+ * reference to the parent device so the parent will not get released until
+ * all references to the cdev are released.
+ *
+ * This helper uses dev->devt for the device number. If it is not set
+ * it will not add the cdev and it will be equivalent to device_add.
+ *
+ * This function should be used whenever the struct cdev and the
+ * struct device are members of the same structure whose lifetime is
+ * managed by the struct device.
+ *
+ * NOTE: Callers must assume that userspace was able to open the cdev and
+ * can call cdev fops callbacks at any time, even if this function fails.
+ */
+int cdev_device_add(struct cdev *cdev, struct device *dev)
+{
+	int rc = 0;
+
+	if (dev->devt) {
+		cdev_set_parent(cdev, &dev->kobj);
+
+		rc = cdev_add(cdev, dev->devt, 1);
+		if (rc)
+			return rc;
+	}
+
+	rc = device_add(dev);
+	if (rc)
+		cdev_del(cdev);
+
+	return rc;
+}
+
+/**
+ * cdev_device_del() - inverse of cdev_device_add
+ * @dev: the device structure
+ * @cdev: the cdev structure
+ *
+ * cdev_device_del() is a helper function to call cdev_del and device_del.
+ * It should be used whenever cdev_device_add is used.
+ *
+ * If dev->devt is not set it will not remove the cdev and will be equivalent
+ * to device_del.
+ *
+ * NOTE: This guarantees that associated sysfs callbacks are not running
+ * or runnable, however any cdevs already open will remain and their fops
+ * will still be callable even after this function returns.
+ */
+void cdev_device_del(struct cdev *cdev, struct device *dev)
+{
+	device_del(dev);
+	if (dev->devt)
+		cdev_del(cdev);
+}
+
 static void cdev_unmap(dev_t dev, unsigned count)
 {
 	kobj_unmap(cdev_map, dev, count);
@@ -483,6 +562,10 @@ static void cdev_unmap(dev_t dev, unsigned count)
  *
  * cdev_del() removes @p from the system, possibly freeing the structure
  * itself.
+ *
+ * NOTE: This guarantees that cdev device will no longer be able to be
+ * opened, however any cdevs already open will remain and their fops will
+ * still be callable even after cdev_del returns.
  */
 void cdev_del(struct cdev *p)
 {
@@ -571,5 +654,8 @@ EXPORT_SYMBOL(cdev_init);
 EXPORT_SYMBOL(cdev_alloc);
 EXPORT_SYMBOL(cdev_del);
 EXPORT_SYMBOL(cdev_add);
+EXPORT_SYMBOL(cdev_set_parent);
+EXPORT_SYMBOL(cdev_device_add);
+EXPORT_SYMBOL(cdev_device_del);
 EXPORT_SYMBOL(__register_chrdev);
 EXPORT_SYMBOL(__unregister_chrdev);