Merge tag 'docs-5.3' of git://git.lwn.net/linux

Pull Documentation updates from Jonathan Corbet:
 "It's been a relatively busy cycle for docs:

   - A fair pile of RST conversions, many from Mauro. These create more
     than the usual number of simple but annoying merge conflicts with
     other trees, unfortunately. He has a lot more of these waiting on
     the wings that, I think, will go to you directly later on.

   - A new document on how to use merges and rebases in kernel repos,
     and one on Spectre vulnerabilities.

   - Various improvements to the build system, including automatic
     markup of function() references because some people, for reasons I
     will never understand, were of the opinion that
     :c:func:``function()`` is unattractive and not fun to type.

   - We now recommend using sphinx 1.7, but still support back to 1.4.

   - Lots of smaller improvements, warning fixes, typo fixes, etc"

* tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits)
  docs: automarkup.py: ignore exceptions when seeking for xrefs
  docs: Move binderfs to admin-guide
  Disable Sphinx SmartyPants in HTML output
  doc: RCU callback locks need only _bh, not necessarily _irq
  docs: format kernel-parameters -- as code
  Doc : doc-guide : Fix a typo
  platform: x86: get rid of a non-existent document
  Add the RCU docs to the core-api manual
  Documentation: RCU: Add TOC tree hooks
  Documentation: RCU: Rename txt files to rst
  Documentation: RCU: Convert RCU UP systems to reST
  Documentation: RCU: Convert RCU linked list to reST
  Documentation: RCU: Convert RCU basic concepts to reST
  docs: filesystems: Remove uneeded .rst extension on toctables
  scripts/sphinx-pre-install: fix out-of-tree build
  docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/
  Documentation: PGP: update for newer HW devices
  Documentation: Add section about CPU vulnerabilities for Spectre
  Documentation: platform: Delete x86-laptop-drivers.txt
  docs: Note that :c:func: should no longer be used
  ...

1 files changed, 98 insertions, 0 deletions

diff --git a/Documentation/fault-injection/notifier-error-inject.rst b/Documentation/fault-injection/notifier-error-inject.rst
new file mode 100644
index 000000000000..1668b6e48d3a
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+Notifier error injection
+========================
+
+Notifier error injection provides the ability to inject artificial errors to
+specified notifier chain callbacks. It is useful to test the error handling of
+notifier call chain failures which is rarely executed.  There are kernel
+modules that can be used to test the following notifiers.
+
+ * PM notifier
+ * Memory hotplug notifier
+ * powerpc pSeries reconfig notifier
+ * Netdevice notifier
+
+PM notifier error injection module
+----------------------------------
+This feature is controlled through debugfs interface
+
+  /sys/kernel/debug/notifier-error-inject/pm/actions/<notifier event>/error
+
+Possible PM notifier events to be failed are:
+
+ * PM_HIBERNATION_PREPARE
+ * PM_SUSPEND_PREPARE
+ * PM_RESTORE_PREPARE
+
+Example: Inject PM suspend error (-12 = -ENOMEM)::
+
+	# cd /sys/kernel/debug/notifier-error-inject/pm/
+	# echo -12 > actions/PM_SUSPEND_PREPARE/error
+	# echo mem > /sys/power/state
+	bash: echo: write error: Cannot allocate memory
+
+Memory hotplug notifier error injection module
+----------------------------------------------
+This feature is controlled through debugfs interface
+
+  /sys/kernel/debug/notifier-error-inject/memory/actions/<notifier event>/error
+
+Possible memory notifier events to be failed are:
+
+ * MEM_GOING_ONLINE
+ * MEM_GOING_OFFLINE
+
+Example: Inject memory hotplug offline error (-12 == -ENOMEM)::
+
+	# cd /sys/kernel/debug/notifier-error-inject/memory
+	# echo -12 > actions/MEM_GOING_OFFLINE/error
+	# echo offline > /sys/devices/system/memory/memoryXXX/state
+	bash: echo: write error: Cannot allocate memory
+
+powerpc pSeries reconfig notifier error injection module
+--------------------------------------------------------
+This feature is controlled through debugfs interface
+
+  /sys/kernel/debug/notifier-error-inject/pSeries-reconfig/actions/<notifier event>/error
+
+Possible pSeries reconfig notifier events to be failed are:
+
+ * PSERIES_RECONFIG_ADD
+ * PSERIES_RECONFIG_REMOVE
+ * PSERIES_DRCONF_MEM_ADD
+ * PSERIES_DRCONF_MEM_REMOVE
+
+Netdevice notifier error injection module
+----------------------------------------------
+This feature is controlled through debugfs interface
+
+  /sys/kernel/debug/notifier-error-inject/netdev/actions/<notifier event>/error
+
+Netdevice notifier events which can be failed are:
+
+ * NETDEV_REGISTER
+ * NETDEV_CHANGEMTU
+ * NETDEV_CHANGENAME
+ * NETDEV_PRE_UP
+ * NETDEV_PRE_TYPE_CHANGE
+ * NETDEV_POST_INIT
+ * NETDEV_PRECHANGEMTU
+ * NETDEV_PRECHANGEUPPER
+ * NETDEV_CHANGEUPPER
+
+Example: Inject netdevice mtu change error (-22 == -EINVAL)::
+
+	# cd /sys/kernel/debug/notifier-error-inject/netdev
+	# echo -22 > actions/NETDEV_CHANGEMTU/error
+	# ip link set eth0 mtu 1024
+	RTNETLINK answers: Invalid argument
+
+For more usage examples
+-----------------------
+There are tools/testing/selftests using the notifier error injection features
+for CPU and memory notifiers.
+
+ * tools/testing/selftests/cpu-hotplug/on-off-test.sh
+ * tools/testing/selftests/memory-hotplug/on-off-test.sh
+
+These scripts first do simple online and offline tests and then do fault
+injection tests if notifier error injection module is available.