Merge branch 'docs-next' of git://git.lwn.net/linux

Pull documentation updates from Jonathan Corbet:
 "After a fair amount of churn in the last couple of cycles, docs are
  taking it easier this time around. Lots of fixes and some new
  documentation, but nothing all that radical. Perhaps the most
  interesting change for many is the scripts/sphinx-pre-install tool
  from Mauro; it will tell you exactly which packages you need to
  install to get a working docs toolchain on your system.

  There are two little patches reaching outside of Documentation/; both
  just tweak kerneldoc comments to eliminate warnings and fix some
  dangling doc pointers"

* 'docs-next' of git://git.lwn.net/linux: (52 commits)
  Documentation/sphinx: fix kernel-doc decode for non-utf-8 locale
  genalloc: Fix an incorrect kerneldoc comment
  doc: Add documentation for the genalloc subsystem
  assoc_array: fix path to assoc_array documentation
  kernel-doc parser mishandles declarations split into lines
  docs: ReSTify table of contents in core.rst
  docs: process: drop git snapshots from applying-patches.rst
  Documentation:input: fix typo
  swap: Remove obsolete sentence
  sphinx.rst: Allow Sphinx version 1.6 at the docs
  docs-rst: fix verbatim font size on tables
  Documentation: stable-kernel-rules: fix broken git urls
  rtmutex: update rt-mutex
  rtmutex: update rt-mutex-design
  docs: fix minimal sphinx version in conf.py
  docs: fix nested numbering in the TOC
  NVMEM documentation fix: A minor typo
  docs-rst: pdf: use same vertical margin on all Sphinx versions
  doc: Makefile: if sphinx is not found, run a check script
  docs: Fix paths in security/keys
  ...

Documentation/Makefile

@@ -22,6 +22,8 @@ ifeq ($(HAVE_SPHINX),0)
 
 .DEFAULT:
 	$(warning The '$(SPHINXBUILD)' command was not found. Make sure you have Sphinx installed and in PATH, or set the SPHINXBUILD make variable to point to the full path of the '$(SPHINXBUILD)' executable.)
+	@echo
+	@./scripts/sphinx-pre-install
 	@echo "  SKIP    Sphinx $@ target."
 
 else # HAVE_SPHINX
@@ -95,16 +97,6 @@ endif # HAVE_SPHINX
 # The following targets are independent of HAVE_SPHINX, and the rules should
 # work or silently pass without Sphinx.
 
-# no-ops for the Sphinx toolchain
-sgmldocs:
-	@:
-psdocs:
-	@:
-mandocs:
-	@:
-installmandocs:
-	@:
-
 cleandocs:
 	$(Q)rm -rf $(BUILDDIR)
 	$(Q)$(MAKE) BUILDDIR=$(abspath $(BUILDDIR)) $(build)=Documentation/media clean

Documentation/arm/firmware.txt

@@ -60,7 +60,7 @@ Example of using a firmware operation:
 
 	/* some platform code, e.g. SMP initialization */
 
-	__raw_writel(virt_to_phys(exynos4_secondary_startup),
+	__raw_writel(__pa_symbol(exynos4_secondary_startup),
 		CPU1_BOOT_REG);
 
 	/* Call Exynos specific smc call */

Documentation/conf.py

@@ -29,7 +29,7 @@ from load_config import loadConfig
 # -- General configuration ------------------------------------------------
 
 # If your documentation needs a minimal Sphinx version, state it here.
-needs_sphinx = '1.2'
+needs_sphinx = '1.3'
 
 # Add any Sphinx extension module names here, as strings. They can be
 # extensions coming with Sphinx (named 'sphinx.ext.*') or your custom
@@ -344,8 +344,8 @@ if major == 1 and minor > 3:
 if major == 1 and minor <= 4:
     latex_elements['preamble']  += '\\usepackage[margin=0.5in, top=1in, bottom=1in]{geometry}'
 elif major == 1 and (minor > 5 or (minor == 5 and patch >= 3)):
-    latex_elements['sphinxsetup'] = 'hmargin=0.5in, vmargin=0.5in'
-
+    latex_elements['sphinxsetup'] = 'hmargin=0.5in, vmargin=1in'
+    latex_elements['preamble']  += '\\fvset{fontsize=auto}\n'
 
 # Grouping the document tree into LaTeX files. List of tuples
 # (source start file, target name, title,

Documentation/core-api/genalloc.rst

@@ -0,0 +1,144 @@
+The genalloc/genpool subsystem
+==============================
+
+There are a number of memory-allocation subsystems in the kernel, each
+aimed at a specific need.  Sometimes, however, a kernel developer needs to
+implement a new allocator for a specific range of special-purpose memory;
+often that memory is located on a device somewhere.  The author of the
+driver for that device can certainly write a little allocator to get the
+job done, but that is the way to fill the kernel with dozens of poorly
+tested allocators.  Back in 2005, Jes Sorensen lifted one of those
+allocators from the sym53c8xx_2 driver and posted_ it as a generic module
+for the creation of ad hoc memory allocators.  This code was merged
+for the 2.6.13 release; it has been modified considerably since then.
+
+.. _posted: https://lwn.net/Articles/125842/
+
+Code using this allocator should include <linux/genalloc.h>.  The action
+begins with the creation of a pool using one of:
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_create		
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: devm_gen_pool_create
+
+A call to :c:func:`gen_pool_create` will create a pool.  The granularity of
+allocations is set with min_alloc_order; it is a log-base-2 number like
+those used by the page allocator, but it refers to bytes rather than pages.
+So, if min_alloc_order is passed as 3, then all allocations will be a
+multiple of eight bytes.  Increasing min_alloc_order decreases the memory
+required to track the memory in the pool.  The nid parameter specifies
+which NUMA node should be used for the allocation of the housekeeping
+structures; it can be -1 if the caller doesn't care.
+
+The "managed" interface :c:func:`devm_gen_pool_create` ties the pool to a
+specific device.  Among other things, it will automatically clean up the
+pool when the given device is destroyed.
+
+A pool is shut down with:
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_destroy
+
+It's worth noting that, if there are still allocations outstanding from the
+given pool, this function will take the rather extreme step of invoking
+BUG(), crashing the entire system.  You have been warned.
+
+A freshly created pool has no memory to allocate.  It is fairly useless in
+that state, so one of the first orders of business is usually to add memory
+to the pool.  That can be done with one of:
+
+.. kernel-doc:: include/linux/genalloc.h
+   :functions: gen_pool_add
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_add_virt
+
+A call to :c:func:`gen_pool_add` will place the size bytes of memory
+starting at addr (in the kernel's virtual address space) into the given
+pool, once again using nid as the node ID for ancillary memory allocations.
+The :c:func:`gen_pool_add_virt` variant associates an explicit physical
+address with the memory; this is only necessary if the pool will be used
+for DMA allocations.
+
+The functions for allocating memory from the pool (and putting it back)
+are:
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_alloc
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_dma_alloc
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_free
+
+As one would expect, :c:func:`gen_pool_alloc` will allocate size< bytes
+from the given pool.  The :c:func:`gen_pool_dma_alloc` variant allocates
+memory for use with DMA operations, returning the associated physical
+address in the space pointed to by dma.  This will only work if the memory
+was added with :c:func:`gen_pool_add_virt`.  Note that this function
+departs from the usual genpool pattern of using unsigned long values to
+represent kernel addresses; it returns a void * instead.
+
+That all seems relatively simple; indeed, some developers clearly found it
+to be too simple.  After all, the interface above provides no control over
+how the allocation functions choose which specific piece of memory to
+return.  If that sort of control is needed, the following functions will be
+of interest:
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_alloc_algo
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_set_algo
+
+Allocations with :c:func:`gen_pool_alloc_algo` specify an algorithm to be
+used to choose the memory to be allocated; the default algorithm can be set
+with :c:func:`gen_pool_set_algo`.  The data value is passed to the
+algorithm; most ignore it, but it is occasionally needed.  One can,
+naturally, write a special-purpose algorithm, but there is a fair set
+already available:
+
+- gen_pool_first_fit is a simple first-fit allocator; this is the default
+  algorithm if none other has been specified.
+
+- gen_pool_first_fit_align forces the allocation to have a specific
+  alignment (passed via data in a genpool_data_align structure).
+
+- gen_pool_first_fit_order_align aligns the allocation to the order of the
+  size.  A 60-byte allocation will thus be 64-byte aligned, for example.
+
+- gen_pool_best_fit, as one would expect, is a simple best-fit allocator.
+
+- gen_pool_fixed_alloc allocates at a specific offset (passed in a
+  genpool_data_fixed structure via the data parameter) within the pool.
+  If the indicated memory is not available the allocation fails.
+
+There is a handful of other functions, mostly for purposes like querying
+the space available in the pool or iterating through chunks of memory.
+Most users, however, should not need much beyond what has been described
+above.  With luck, wider awareness of this module will help to prevent the
+writing of special-purpose memory allocators in the future.
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_virt_to_phys
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_for_each_chunk
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: addr_in_gen_pool
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_avail
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_size
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: gen_pool_get
+
+.. kernel-doc:: lib/genalloc.c
+   :functions: of_gen_pool_get

Documentation/core-api/index.rst

@@ -20,6 +20,7 @@ Core utilities
    genericirq
    flexible-arrays
    librs
+   genalloc
 
 Interfaces for kernel debugging
 ===============================

Documentation/dev-tools/gdb-kernel-debugging.rst

@@ -31,11 +31,13 @@ Setup
   CONFIG_DEBUG_INFO_REDUCED off. If your architecture supports
   CONFIG_FRAME_POINTER, keep it enabled.
 
-- Install that kernel on the guest.
+- Install that kernel on the guest, turn off KASLR if necessary by adding
+  "nokaslr" to the kernel command line.
   Alternatively, QEMU allows to boot the kernel directly using -kernel,
   -append, -initrd command line switches. This is generally only useful if
   you do not depend on modules. See QEMU documentation for more details on
-  this mode.
+  this mode. In this case, you should build the kernel with
+  CONFIG_RANDOMIZE_BASE disabled if the architecture supports KASLR.
 
 - Enable the gdb stub of QEMU/KVM, either
 

Documentation/dev-tools/kgdb.rst

@@ -348,6 +348,15 @@ default behavior is always set to 0.
     - ``echo 1 > /sys/module/debug_core/parameters/kgdbreboot``
     - Enter the debugger on reboot notify.
 
+Kernel parameter: ``nokaslr``
+-----------------------------
+
+If the architecture that you are using enable KASLR by default,
+you should consider turning it off.  KASLR randomizes the
+virtual address where the kernel image is mapped and confuse
+gdb which resolve kernel symbol address from symbol table
+of vmlinux.
+
 Using kdb
 =========
 
@@ -358,7 +367,7 @@ This is a quick example of how to use kdb.
 
 1. Configure kgdboc at boot using kernel parameters::
 
-	console=ttyS0,115200 kgdboc=ttyS0,115200
+	console=ttyS0,115200 kgdboc=ttyS0,115200 nokaslr
 
    OR
 

Documentation/doc-guide/sphinx.rst

@@ -19,6 +19,110 @@ Finally, there are thousands of plain text documentation files scattered around
 ``Documentation``. Some of these will likely be converted to reStructuredText
 over time, but the bulk of them will remain in plain text.
 
+.. _sphinx_install:
+
+Sphinx Install
+==============
+
+The ReST markups currently used by the Documentation/ files are meant to be
+built with ``Sphinx`` version 1.3 or upper. If you're desiring to build
+PDF outputs, it is recommended to use version 1.4.6 or upper.
+
+There's a script that checks for the Spinx requirements. Please see
+:ref:`sphinx-pre-install` for further details.
+
+Most distributions are shipped with Sphinx, but its toolchain is fragile,
+and it is not uncommon that upgrading it or some other Python packages
+on your machine would cause the documentation build to break.
+
+A way to get rid of that is to use a different version than the one shipped
+on your distributions. In order to do that, it is recommended to install
+Sphinx inside a virtual environment, using ``virtualenv-3``
+or ``virtualenv``, depending on how your distribution packaged Python 3.
+
+.. note::
+
+   #) Sphinx versions below 1.5 don't work properly with Python's
+      docutils version 0.13.1 or upper. So, if you're willing to use
+      those versions, you should run ``pip install 'docutils==0.12'``.
+
+   #) It is recommended to use the RTD theme for html output. Depending
+      on the Sphinx version, it should be installed  in separate,
+      with ``pip install sphinx_rtd_theme``.
+
+   #) Some ReST pages contain math expressions. Due to the way Sphinx work,
+      those expressions are written using LaTeX notation. It needs texlive
+      installed with amdfonts and amsmath in order to evaluate them.
+
+In summary, if you want to install Sphinx version 1.4.9, you should do::
+
+       $ virtualenv sphinx_1.4
+       $ . sphinx_1.4/bin/activate
+       (sphinx_1.4) $ pip install -r Documentation/sphinx/requirements.txt
+
+After running ``. sphinx_1.4/bin/activate``, the prompt will change,
+in order to indicate that you're using the new environment. If you
+open a new shell, you need to rerun this command to enter again at
+the virtual environment before building the documentation.
+
+Image output
+------------
+
+The kernel documentation build system contains an extension that
+handles images on both GraphViz and SVG formats (see
+:ref:`sphinx_kfigure`).
+
+For it to work, you need to install both GraphViz and ImageMagick
+packages. If those packages are not installed, the build system will
+still build the documentation, but won't include any images at the
+output.
+
+PDF and LaTeX builds
+--------------------
+
+Such builds are currently supported only with Sphinx versions 1.4 and upper.
+
+For PDF and LaTeX output, you'll also need ``XeLaTeX`` version 3.14159265.
+
+Depending on the distribution, you may also need to install a series of
+``texlive`` packages that provide the minimal set of functionalities
+required for ``XeLaTeX`` to work.
+
+.. _sphinx-pre-install:
+
+Checking for Sphinx dependencies
+--------------------------------
+
+There's a script that automatically check for Sphinx dependencies. If it can
+recognize your distribution, it will also give a hint about the install
+command line options for your distro::
+
+	$ ./scripts/sphinx-pre-install
+	Checking if the needed tools for Fedora release 26 (Twenty Six) are available
+	Warning: better to also install "texlive-luatex85".
+	You should run:
+
+		sudo dnf install -y texlive-luatex85
+		/usr/bin/virtualenv sphinx_1.4
+		. sphinx_1.4/bin/activate
+		pip install -r Documentation/sphinx/requirements.txt
+
+	Can't build as 1 mandatory dependency is missing at ./scripts/sphinx-pre-install line 468.
+
+By default, it checks all the requirements for both html and PDF, including
+the requirements for images, math expressions and LaTeX build, and assumes
+that a virtual Python environment will be used. The ones needed for html
+builds are assumed to be mandatory; the others to be optional.
+
+It supports two optional parameters:
+
+``--no-pdf``
+	Disable checks for PDF;
+
+``--no-virtualenv``
+	Use OS packaging for Sphinx instead of Python virtual environment.
+
+
 Sphinx Build
 ============
 
@@ -118,7 +222,7 @@ Here are some specific guidelines for the kernel documentation:
 the C domain
 ------------
 
-The `Sphinx C Domain`_ (name c) is suited for documentation of C API. E.g. a
+The **Sphinx C Domain** (name c) is suited for documentation of C API. E.g. a
 function prototype:
 
 .. code-block:: rst
@@ -229,6 +333,7 @@ Rendered as:
 
         - column 3
 
+.. _sphinx_kfigure:
 
 Figures & Images
 ================

Documentation/driver-api/basics.rst

@@ -4,7 +4,7 @@ Driver Basics
 Driver Entry and Exit points
 ----------------------------
 
-.. kernel-doc:: include/linux/init.h
+.. kernel-doc:: include/linux/module.h
    :internal:
 
 Driver device table
@@ -103,9 +103,6 @@ Kernel utility functions
 .. kernel-doc:: kernel/panic.c
    :export:
 
-.. kernel-doc:: kernel/sys.c
-   :export:
-
 .. kernel-doc:: kernel/rcu/tree.c
    :export:
 

Documentation/driver-api/dma-buf.rst

@@ -139,9 +139,6 @@ DMA Fences
 Seqno Hardware Fences
 ~~~~~~~~~~~~~~~~~~~~~
 
-.. kernel-doc:: drivers/dma-buf/seqno-fence.c
-   :export:
-
 .. kernel-doc:: include/linux/seqno-fence.h
    :internal:
 

Documentation/driver-api/miscellaneous.rst

@@ -47,4 +47,3 @@ used by one consumer at a time.
 
 .. kernel-doc:: drivers/pwm/core.c
    :export:
-   

Documentation/driver-api/s390-drivers.rst

@@ -75,7 +75,7 @@ The channel-measurement facility provides a means to collect measurement
 data which is made available by the channel subsystem for each channel
 attached device.
 
-.. kernel-doc:: arch/s390/include/asm/cmb.h
+.. kernel-doc:: arch/s390/include/uapi/asm/cmb.h
    :internal:
 
 .. kernel-doc:: drivers/s390/cio/cmf.c

Documentation/driver-api/scsi.rst

@@ -224,14 +224,6 @@ mid to lowlevel SCSI driver interface
 .. kernel-doc:: drivers/scsi/hosts.c
    :export:
 
-drivers/scsi/constants.c
-~~~~~~~~~~~~~~~~~~~~~~~~
-
-mid to lowlevel SCSI driver interface
-
-.. kernel-doc:: drivers/scsi/constants.c
-   :export:
-
 Transport classes
 -----------------
 

Documentation/features/core/tracehook/arch-support.txt

@@ -25,7 +25,7 @@
     |     mn10300: |  ok  |
     |       nios2: |  ok  |
     |    openrisc: |  ok  |
-    |      parisc: | TODO |
+    |      parisc: |  ok  |
     |     powerpc: |  ok  |
     |        s390: |  ok  |
     |       score: | TODO |

Documentation/filesystems/vfs.txt

@@ -829,9 +829,7 @@ struct address_space_operations {
   swap_activate: Called when swapon is used on a file to allocate
 	space if necessary and pin the block lookup information in
 	memory. A return value of zero indicates success,
-	in which case this file can be used to back swapspace. The
-	swapspace operations will be proxied to this address space's
-	->swap_{out,in} methods.
+	in which case this file can be used to back swapspace.
 
   swap_deactivate: Called during swapoff on files where swap_activate
 	was successful.

Documentation/input/input.rst

@@ -109,7 +109,7 @@ evdev nodes are created with minors starting with 256.
 keyboard
 ~~~~~~~~
 
-``keyboard`` is in-kernel input handler ad is a part of VT code. It
+``keyboard`` is in-kernel input handler and is a part of VT code. It
 consumes keyboard keystrokes and handles user input for VT consoles.
 
 mousedev

Documentation/input/joydev/index.rst

@@ -12,7 +12,6 @@ Linux Joystick support
 
 .. toctree::
 	:maxdepth: 3
-	:numbered:
 
 	joystick
 	joystick-api

Documentation/kbuild/makefiles.txt

@@ -297,9 +297,9 @@ more details, with real examples.
 	ccflags-y specifies options for compiling with $(CC).
 
 	Example:
-		# drivers/acpi/Makefile
-		ccflags-y := -Os
-		ccflags-$(CONFIG_ACPI_DEBUG) += -DACPI_DEBUG_OUTPUT
+		# drivers/acpi/acpica/Makefile
+		ccflags-y			:= -Os -D_LINUX -DBUILDING_ACPICA
+		ccflags-$(CONFIG_ACPI_DEBUG)	+= -DACPI_DEBUG_OUTPUT
 
 	This variable is necessary because the top Makefile owns the
 	variable $(KBUILD_CFLAGS) and uses it for compilation flags for the

Documentation/locking/rt-mutex.txt

@@ -28,14 +28,13 @@ magic bullet for poorly designed applications, but it allows
 well-designed applications to use userspace locks in critical parts of
 an high priority thread, without losing determinism.
 
-The enqueueing of the waiters into the rtmutex waiter list is done in
+The enqueueing of the waiters into the rtmutex waiter tree is done in
 priority order. For same priorities FIFO order is chosen. For each
 rtmutex, only the top priority waiter is enqueued into the owner's
-priority waiters list. This list too queues in priority order. Whenever
+priority waiters tree. This tree too queues in priority order. Whenever
 the top priority waiter of a task changes (for example it timed out or
-got a signal), the priority of the owner task is readjusted. [The
-priority enqueueing is handled by "plists", see include/linux/plist.h
-for more details.]
+got a signal), the priority of the owner task is readjusted. The
+priority enqueueing is handled by "pi_waiters".
 
 RT-mutexes are optimized for fastpath operations and have no internal
 locking overhead when locking an uncontended mutex or unlocking a mutex
@@ -46,34 +45,29 @@ is used]
 The state of the rt-mutex is tracked via the owner field of the rt-mutex
 structure:
 
-rt_mutex->owner holds the task_struct pointer of the owner. Bit 0 and 1
-are used to keep track of the "owner is pending" and "rtmutex has
-waiters" state.
+lock->owner holds the task_struct pointer of the owner. Bit 0 is used to
+keep track of the "lock has waiters" state.
 
- owner		bit1	bit0
- NULL		0	0	mutex is free (fast acquire possible)
- NULL		0	1	invalid state
- NULL		1	0	Transitional state*
- NULL		1	1	invalid state
- taskpointer	0	0	mutex is held (fast release possible)
- taskpointer	0	1	task is pending owner
- taskpointer	1	0	mutex is held and has waiters
- taskpointer	1	1	task is pending owner and mutex has waiters
+ owner        bit0
+ NULL         0       lock is free (fast acquire possible)
+ NULL         1       lock is free and has waiters and the top waiter
+			is going to take the lock*
+ taskpointer  0       lock is held (fast release possible)
+ taskpointer  1       lock is held and has waiters**
 
-Pending-ownership handling is a performance optimization:
-pending-ownership is assigned to the first (highest priority) waiter of
-the mutex, when the mutex is released. The thread is woken up and once
-it starts executing it can acquire the mutex. Until the mutex is taken
-by it (bit 0 is cleared) a competing higher priority thread can "steal"
-the mutex which puts the woken up thread back on the waiters list.
+The fast atomic compare exchange based acquire and release is only
+possible when bit 0 of lock->owner is 0.
 
-The pending-ownership optimization is especially important for the
-uninterrupted workflow of high-prio tasks which repeatedly
-takes/releases locks that have lower-prio waiters. Without this
-optimization the higher-prio thread would ping-pong to the lower-prio
-task [because at unlock time we always assign a new owner].
+(*) It also can be a transitional state when grabbing the lock
+with ->wait_lock is held. To prevent any fast path cmpxchg to the lock,
+we need to set the bit0 before looking at the lock, and the owner may be
+NULL in this small time, hence this can be a transitional state.
 
-(*) The "mutex has waiters" bit gets set to take the lock. If the lock
-doesn't already have an owner, this bit is quickly cleared if there are
-no waiters.  So this is a transitional state to synchronize with looking
-at the owner field of the mutex and the mutex owner releasing the lock.
+(**) There is a small time when bit 0 is set but there are no
+waiters. This can happen when grabbing the lock in the slow path.
+To prevent a cmpxchg of the owner releasing the lock, we need to
+set this bit before looking at the lock.
+
+BTW, there is still technically a "Pending Owner", it's just not called
+that anymore. The pending owner happens to be the top_waiter of a lock
+that has no owner and has been woken up to grab the lock.