Merge tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-tracegrafted

Pull tracing fixes from Steven Rostedt:

 - Fix error output of boot instance creation failure

   Currently if a boot instance creation fails, instead of printing out
   the name of the instance that failed, it prints "(null)". That is
   because it prints "cur_str" that had already been processed by
   strsep(). Print the saved name instead.

   While at it, print the error code of the failure.

 - Fix use-after-free for same named historgrams

   Histograms can be named so that they can be used in multiple events.
   But if the named histogram has a variable attached, the second event
   that uses the named histogram which duplicates it and needs to free
   the original after duplication leaves the old variable in place and
   still visible. If another histogram uses than variable, it will use
   the stale one which will try to reference the freed duplicate
   histogram and crash the kernel.

   Free the duplicate variables along with the duplicated histogram
   data.

 - Check return value of kthread_run() in event self test

   The events self tests uses a kthread for testing but does not check
   if it succeeded in creating a kthread. If the kthread creation were
   to fail, the code will still try to call kthread_stop() on the error
   returned.

 - Fix race between reading trace_pipe and updating subbuffer size

   If a user is reading the trace_pipe file at the same time they update
   the ring buffer sub-buffer size, can cause the trace_pipe read to
   read stale data. Add trace_access_lock() around updating the ring
   buffer sub-buffer size.

 - Fix eventfs_inode on failure path in creation of the events directory

   In the creation of the "events" directory, if after allocating the
   eventfs_inode a failure is detected, it calls cleanup_ei() which
   calls free_ei(). The free_ei() will test if eventfs_inode being freed
   has no children. It is a bug if it does. But on the failure case of
   the creation of the "events" directory, the children lists have not
   yet been initialized and the free will trigger a warning because
   list_empty() on an uninitialized list returns false.

   Move the initialization into init_ei() where it makes more sense and
   makes sure that a created eventfs_inode has its lists initialized
   upon creation.

 - Check return value of kthread_run() in ftrace direct sample code

   The sample code that shows how to use the ftrace direct calls does
   not test the return of kthread_run() to see if it succeeds. Return a
   failure if the kthread_run() doesn't succeed.

 - Clear user events state on fork in case of alloc failure

   On fork, the child gets a pointer to the parent's user events state.
   It makes a copy of it then updates the child's pointer to it. But if
   the allocation fails, the duplication function leaves the child with
   a pointer to its parent's descriptor. When the child cleans up its
   data, it will free the parent's descriptor while the parent is still
   using it.

   In the duplication function, set the child's user_event_mm to NULL
   before testing if the allocation succeeded, and when it exits it will
   not free the parent's descriptor.

 - Fix retry exhaustion in simple ring buffer reader swap

   simple_ring_buffer_swap_reader_page() starts with retry set to 8 and
   post-decrements it only after a failed link replacement. On the final
   attempt, a successful replacement leaves retry at zero, while a
   failed replacement leaves it at -1.

   But the check for success expects the retry value to be non-zero and
   exits with an error on zero. This is the opposite result. Fix it.

 - Fail nicely when the remote swap_reader_page() returns an error

   Currently, if the swap_reader_page() of a remote buffer fails, it
   triggers a WARN_ON_ONCE() and continues normally. Instead, have it
   exit with an error and a pr_warn() print instead of a full WARNING.

* tag 'trace-v7.3-2' of git://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace:
  ring-buffer: Stop remote reader update when page swap fails
  tracing: Fix retry exhaustion in simple ring buffer reader swap
  tracing/user_events: Clear copied tracing state before fork duplication
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-multi-modify
  samples/ftrace: Fix kthread_stop() on ERR_PTR in ftrace-direct-modify
  eventfs: Initialize ei->children and ei->list in init_ei()
  tracing: Fix use-after-free in trace_pipe read on sub-buffer order change
  tracing: Fix crash passing ERR_PTR to kthread_stop()
  tracing: Fix use-after-free with same-name named triggers
  tracing: Fix logged instance name on creation failure

3 files changed, 370 insertions, 0 deletions

diff --git a/Documentation/driver-api/phy/index.rst b/Documentation/driver-api/phy/index.rst
new file mode 100644
index 000000000..579cfe3b7
--- /dev/null
+++ b/Documentation/driver-api/phy/index.rst
@@ -0,0 +1,10 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+Generic PHY Framework
+=====================
+
+.. toctree::
+
+   phy
+   samsung-usb2
diff --git a/Documentation/driver-api/phy/phy.rst b/Documentation/driver-api/phy/phy.rst
new file mode 100644
index 000000000..0865c2e94
--- /dev/null
+++ b/Documentation/driver-api/phy/phy.rst
@@ -0,0 +1,223 @@
+=============
+PHY subsystem
+=============
+
+:Author: Kishon Vijay Abraham I <kishon@ti.com>
+
+This document explains the Generic PHY Framework along with the APIs provided,
+and how-to-use.
+
+Introduction
+============
+
+*PHY* is the abbreviation for physical layer. It is used to connect a device
+to the physical medium e.g., the USB controller has a PHY to provide functions
+such as serialization, de-serialization, encoding, decoding and is responsible
+for obtaining the required data transmission rate. Note that some USB
+controllers have PHY functionality embedded into it and others use an external
+PHY. Other peripherals that use PHY include Wireless LAN, Ethernet,
+SATA etc.
+
+The intention of creating this framework is to bring the PHY drivers spread
+all over the Linux kernel to drivers/phy to increase code reuse and for
+better code maintainability.
+
+This framework will be of use only to devices that use external PHY (PHY
+functionality is not embedded within the controller).
+
+Registering/Unregistering the PHY provider
+==========================================
+
+PHY provider refers to an entity that implements one or more PHY instances.
+For the simple case where the PHY provider implements only a single instance of
+the PHY, the framework provides its own implementation of of_xlate in
+of_phy_simple_xlate. If the PHY provider implements multiple instances, it
+should provide its own implementation of of_xlate. of_xlate is used only for
+dt boot case.
+
+::
+
+	#define of_phy_provider_register(dev, xlate)    \
+		__of_phy_provider_register((dev), NULL, THIS_MODULE, (xlate))
+
+	#define devm_of_phy_provider_register(dev, xlate)       \
+		__devm_of_phy_provider_register((dev), NULL, THIS_MODULE,
+						(xlate))
+
+of_phy_provider_register and devm_of_phy_provider_register macros can be used to
+register the phy_provider and it takes device and of_xlate as
+arguments. For the dt boot case, all PHY providers should use one of the above
+2 macros to register the PHY provider.
+
+Often the device tree nodes associated with a PHY provider will contain a set
+of children that each represent a single PHY. Some bindings may nest the child
+nodes within extra levels for context and extensibility, in which case the low
+level of_phy_provider_register_full() and devm_of_phy_provider_register_full()
+macros can be used to override the node containing the children.
+
+::
+
+	#define of_phy_provider_register_full(dev, children, xlate) \
+		__of_phy_provider_register(dev, children, THIS_MODULE, xlate)
+
+	#define devm_of_phy_provider_register_full(dev, children, xlate) \
+		__devm_of_phy_provider_register_full(dev, children,
+						     THIS_MODULE, xlate)
+
+	void devm_of_phy_provider_unregister(struct device *dev,
+		struct phy_provider *phy_provider);
+	void of_phy_provider_unregister(struct phy_provider *phy_provider);
+
+devm_of_phy_provider_unregister and of_phy_provider_unregister can be used to
+unregister the PHY.
+
+Creating the PHY
+================
+
+The PHY driver should create the PHY in order for other peripheral controllers
+to make use of it. The PHY framework provides 2 APIs to create the PHY.
+
+::
+
+	struct phy *phy_create(struct device *dev, struct device_node *node,
+			       const struct phy_ops *ops);
+	struct phy *devm_phy_create(struct device *dev,
+				    struct device_node *node,
+				    const struct phy_ops *ops);
+
+The PHY drivers can use one of the above 2 APIs to create the PHY by passing
+the device pointer and phy ops.
+phy_ops is a set of function pointers for performing PHY operations such as
+init, exit, power_on and power_off.
+
+Inorder to dereference the private data (in phy_ops), the phy provider driver
+can use phy_set_drvdata() after creating the PHY and use phy_get_drvdata() in
+phy_ops to get back the private data.
+
+Getting a reference to the PHY
+==============================
+
+Before the controller can make use of the PHY, it has to get a reference to
+it. This framework provides the following APIs to get a reference to the PHY.
+
+::
+
+	struct phy *phy_get(struct device *dev, const char *string);
+	struct phy *devm_phy_get(struct device *dev, const char *string);
+	struct phy *devm_phy_optional_get(struct device *dev,
+					  const char *string);
+	struct phy *devm_of_phy_get(struct device *dev, struct device_node *np,
+				    const char *con_id);
+	struct phy *devm_of_phy_optional_get(struct device *dev,
+					     struct device_node *np,
+					     const char *con_id);
+	struct phy *devm_of_phy_get_by_index(struct device *dev,
+					     struct device_node *np,
+					     int index);
+
+phy_get, devm_phy_get and devm_phy_optional_get can be used to get the PHY.
+In the case of dt boot, the string arguments
+should contain the phy name as given in the dt data and in the case of
+non-dt boot, it should contain the label of the PHY.  The two
+devm_phy_get associates the device with the PHY using devres on
+successful PHY get. On driver detach, release function is invoked on
+the devres data and devres data is freed.
+The _optional_get variants should be used when the phy is optional. These
+functions will never return -ENODEV, but instead return NULL when
+the phy cannot be found.
+Some generic drivers, such as ehci, may use multiple phys. In this case,
+devm_of_phy_get or devm_of_phy_get_by_index can be used to get a phy
+reference based on name or index.
+
+It should be noted that NULL is a valid phy reference. All phy
+consumer calls on the NULL phy become NOPs. That is the release calls,
+the phy_init() and phy_exit() calls, and phy_power_on() and
+phy_power_off() calls are all NOP when applied to a NULL phy. The NULL
+phy is useful in devices for handling optional phy devices.
+
+Order of API calls
+==================
+
+The general order of calls should be::
+
+    [devm_][of_]phy_get()
+    phy_init()
+    phy_power_on()
+    [phy_set_mode[_ext]()]
+    ...
+    phy_power_off()
+    phy_exit()
+    [[of_]phy_put()]
+
+Some PHY drivers may not implement :c:func:`phy_init` or :c:func:`phy_power_on`,
+but controllers should always call these functions to be compatible with other
+PHYs. Some PHYs may require :c:func:`phy_set_mode <phy_set_mode_ext>`, while
+others may use a default mode (typically configured via devicetree or other
+firmware). For compatibility, you should always call this function if you know
+what mode you will be using. Generally, this function should be called after
+:c:func:`phy_power_on`, although some PHY drivers may allow it at any time.
+
+Releasing a reference to the PHY
+================================
+
+When the controller no longer needs the PHY, it has to release the reference
+to the PHY it has obtained using the APIs mentioned in the above section. The
+PHY framework provides 2 APIs to release a reference to the PHY.
+
+::
+
+	void phy_put(struct phy *phy);
+	void devm_phy_put(struct device *dev, struct phy *phy);
+
+Both these APIs are used to release a reference to the PHY and devm_phy_put
+destroys the devres associated with this PHY.
+
+Destroying the PHY
+==================
+
+When the driver that created the PHY is unloaded, it should destroy the PHY it
+created using one of the following 2 APIs::
+
+	void phy_destroy(struct phy *phy);
+	void devm_phy_destroy(struct device *dev, struct phy *phy);
+
+Both these APIs destroy the PHY and devm_phy_destroy destroys the devres
+associated with this PHY.
+
+PM Runtime
+==========
+
+This subsystem is pm runtime enabled. So while creating the PHY,
+pm_runtime_enable of the phy device created by this subsystem is called and
+while destroying the PHY, pm_runtime_disable is called. Note that the phy
+device created by this subsystem will be a child of the device that calls
+phy_create (PHY provider device).
+
+So pm_runtime_get_sync of the phy_device created by this subsystem will invoke
+pm_runtime_get_sync of PHY provider device because of parent-child relationship.
+It should also be noted that phy_power_on and phy_power_off performs
+phy_pm_runtime_get_sync and phy_pm_runtime_put respectively.
+There are exported APIs like phy_pm_runtime_get, phy_pm_runtime_get_sync,
+phy_pm_runtime_put and phy_pm_runtime_put_sync for performing PM operations.
+
+PHY Mappings
+============
+
+In order to get reference to a PHY without help from DeviceTree, the framework
+offers lookups which can be compared to clkdev that allow clk structures to be
+bound to devices. A lookup can be made during runtime when a handle to the
+struct phy already exists.
+
+The framework offers the following API for registering and unregistering the
+lookups::
+
+	int phy_create_lookup(struct phy *phy, const char *con_id,
+			      const char *dev_id);
+	void phy_remove_lookup(struct phy *phy, const char *con_id,
+			       const char *dev_id);
+
+DeviceTree Binding
+==================
+
+The documentation for PHY dt binding can be found @
+Documentation/devicetree/bindings/phy/phy-bindings.txt
diff --git a/Documentation/driver-api/phy/samsung-usb2.rst b/Documentation/driver-api/phy/samsung-usb2.rst
new file mode 100644
index 000000000..c48c8b979
--- /dev/null
+++ b/Documentation/driver-api/phy/samsung-usb2.rst
@@ -0,0 +1,137 @@
+====================================
+Samsung USB 2.0 PHY adaptation layer
+====================================
+
+1. Description
+--------------
+
+The architecture of the USB 2.0 PHY module in Samsung SoCs is similar
+among many SoCs. In spite of the similarities it proved difficult to
+create a one driver that would fit all these PHY controllers. Often
+the differences were minor and were found in particular bits of the
+registers of the PHY. In some rare cases the order of register writes or
+the PHY powering up process had to be altered. This adaptation layer is
+a compromise between having separate drivers and having a single driver
+with added support for many special cases.
+
+2. Files description
+--------------------
+
+- phy-samsung-usb2.c
+   This is the main file of the adaptation layer. This file contains
+   the probe function and provides two callbacks to the Generic PHY
+   Framework. This two callbacks are used to power on and power off the
+   phy. They carry out the common work that has to be done on all version
+   of the PHY module. Depending on which SoC was chosen they execute SoC
+   specific callbacks. The specific SoC version is selected by choosing
+   the appropriate compatible string. In addition, this file contains
+   struct of_device_id definitions for particular SoCs.
+
+- phy-samsung-usb2.h
+   This is the include file. It declares the structures used by this
+   driver. In addition it should contain extern declarations for
+   structures that describe particular SoCs.
+
+3. Supporting SoCs
+------------------
+
+To support a new SoC a new file should be added to the drivers/phy
+directory. Each SoC's configuration is stored in an instance of the
+struct samsung_usb2_phy_config::
+
+  struct samsung_usb2_phy_config {
+	const struct samsung_usb2_common_phy *phys;
+	int (*rate_to_clk)(unsigned long, u32 *);
+	unsigned int num_phys;
+	bool has_mode_switch;
+  };
+
+The num_phys is the number of phys handled by the driver. `*phys` is an
+array that contains the configuration for each phy. The has_mode_switch
+property is a boolean flag that determines whether the SoC has USB host
+and device on a single pair of pins. If so, a special register has to
+be modified to change the internal routing of these pins between a USB
+device or host module.
+
+For example the configuration for Exynos 4210 is following::
+
+  const struct samsung_usb2_phy_config exynos4210_usb2_phy_config = {
+	.has_mode_switch        = 0,
+	.num_phys		= EXYNOS4210_NUM_PHYS,
+	.phys			= exynos4210_phys,
+	.rate_to_clk		= exynos4210_rate_to_clk,
+  }
+
+- `int (*rate_to_clk)(unsigned long, u32 *)`
+
+	The rate_to_clk callback is to convert the rate of the clock
+	used as the reference clock for the PHY module to the value
+	that should be written in the hardware register.
+
+The exynos4210_phys configuration array is as follows::
+
+  static const struct samsung_usb2_common_phy exynos4210_phys[] = {
+	{
+		.label		= "device",
+		.id		= EXYNOS4210_DEVICE,
+		.power_on	= exynos4210_power_on,
+		.power_off	= exynos4210_power_off,
+	},
+	{
+		.label		= "host",
+		.id		= EXYNOS4210_HOST,
+		.power_on	= exynos4210_power_on,
+		.power_off	= exynos4210_power_off,
+	},
+	{
+		.label		= "hsic0",
+		.id		= EXYNOS4210_HSIC0,
+		.power_on	= exynos4210_power_on,
+		.power_off	= exynos4210_power_off,
+	},
+	{
+		.label		= "hsic1",
+		.id		= EXYNOS4210_HSIC1,
+		.power_on	= exynos4210_power_on,
+		.power_off	= exynos4210_power_off,
+	},
+	{},
+  };
+
+- `int (*power_on)(struct samsung_usb2_phy_instance *);`
+  `int (*power_off)(struct samsung_usb2_phy_instance *);`
+
+	These two callbacks are used to power on and power off the phy
+	by modifying appropriate registers.
+
+Final change to the driver is adding appropriate compatible value to the
+phy-samsung-usb2.c file. In case of Exynos 4210 the following lines were
+added to the struct of_device_id samsung_usb2_phy_of_match[] array::
+
+  #ifdef CONFIG_PHY_EXYNOS4210_USB2
+	{
+		.compatible = "samsung,exynos4210-usb2-phy",
+		.data = &exynos4210_usb2_phy_config,
+	},
+  #endif
+
+To add further flexibility to the driver the Kconfig file enables to
+include support for selected SoCs in the compiled driver. The Kconfig
+entry for Exynos 4210 is following::
+
+  config PHY_EXYNOS4210_USB2
+	bool "Support for Exynos 4210"
+	depends on PHY_SAMSUNG_USB2
+	depends on CPU_EXYNOS4210
+	help
+	  Enable USB PHY support for Exynos 4210. This option requires that
+	  Samsung USB 2.0 PHY driver is enabled and means that support for this
+	  particular SoC is compiled in the driver. In case of Exynos 4210 four
+	  phys are available - device, host, HSCI0 and HSCI1.
+
+The newly created file that supports the new SoC has to be also added to the
+Makefile. In case of Exynos 4210 the added line is following::
+
+  obj-$(CONFIG_PHY_EXYNOS4210_USB2)       += phy-exynos4210-usb2.o
+
+After completing these steps the support for the new SoC should be ready.