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, 178 insertions, 0 deletions

diff --git a/Documentation/fault-injection/nvme-fault-injection.rst b/Documentation/fault-injection/nvme-fault-injection.rst
new file mode 100644
index 000000000000..cdb2e829228e
--- /dev/null
+++ b/Documentation/fault-injection/nvme-fault-injection.rst
@@ -0,0 +1,178 @@
+NVMe Fault Injection
+====================
+Linux's fault injection framework provides a systematic way to support
+error injection via debugfs in the /sys/kernel/debug directory. When
+enabled, the default NVME_SC_INVALID_OPCODE with no retry will be
+injected into the nvme_end_request. Users can change the default status
+code and no retry flag via the debugfs. The list of Generic Command
+Status can be found in include/linux/nvme.h
+
+Following examples show how to inject an error into the nvme.
+
+First, enable CONFIG_FAULT_INJECTION_DEBUG_FS kernel config,
+recompile the kernel. After booting up the kernel, do the
+following.
+
+Example 1: Inject default status code with no retry
+---------------------------------------------------
+
+::
+
+  mount /dev/nvme0n1 /mnt
+  echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
+  echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
+  cp a.file /mnt
+
+Expected Result::
+
+  cp: cannot stat ‘/mnt/a.file’: Input/output error
+
+Message from dmesg::
+
+  FAULT_INJECTION: forcing a failure.
+  name fault_inject, interval 1, probability 100, space 0, times 1
+  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.15.0-rc8+ #2
+  Hardware name: innotek GmbH VirtualBox/VirtualBox,
+  BIOS VirtualBox 12/01/2006
+  Call Trace:
+    <IRQ>
+    dump_stack+0x5c/0x7d
+    should_fail+0x148/0x170
+    nvme_should_fail+0x2f/0x50 [nvme_core]
+    nvme_process_cq+0xe7/0x1d0 [nvme]
+    nvme_irq+0x1e/0x40 [nvme]
+    __handle_irq_event_percpu+0x3a/0x190
+    handle_irq_event_percpu+0x30/0x70
+    handle_irq_event+0x36/0x60
+    handle_fasteoi_irq+0x78/0x120
+    handle_irq+0xa7/0x130
+    ? tick_irq_enter+0xa8/0xc0
+    do_IRQ+0x43/0xc0
+    common_interrupt+0xa2/0xa2
+    </IRQ>
+  RIP: 0010:native_safe_halt+0x2/0x10
+  RSP: 0018:ffffffff82003e90 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdd
+  RAX: ffffffff817a10c0 RBX: ffffffff82012480 RCX: 0000000000000000
+  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
+  RBP: 0000000000000000 R08: 000000008e38ce64 R09: 0000000000000000
+  R10: 0000000000000000 R11: 0000000000000000 R12: ffffffff82012480
+  R13: ffffffff82012480 R14: 0000000000000000 R15: 0000000000000000
+    ? __sched_text_end+0x4/0x4
+    default_idle+0x18/0xf0
+    do_idle+0x150/0x1d0
+    cpu_startup_entry+0x6f/0x80
+    start_kernel+0x4c4/0x4e4
+    ? set_init_arg+0x55/0x55
+    secondary_startup_64+0xa5/0xb0
+    print_req_error: I/O error, dev nvme0n1, sector 9240
+  EXT4-fs error (device nvme0n1): ext4_find_entry:1436:
+  inode #2: comm cp: reading directory lblock 0
+
+Example 2: Inject default status code with retry
+------------------------------------------------
+
+::
+
+  mount /dev/nvme0n1 /mnt
+  echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/times
+  echo 100 > /sys/kernel/debug/nvme0n1/fault_inject/probability
+  echo 1 > /sys/kernel/debug/nvme0n1/fault_inject/status
+  echo 0 > /sys/kernel/debug/nvme0n1/fault_inject/dont_retry
+
+  cp a.file /mnt
+
+Expected Result::
+
+  command success without error
+
+Message from dmesg::
+
+  FAULT_INJECTION: forcing a failure.
+  name fault_inject, interval 1, probability 100, space 0, times 1
+  CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.15.0-rc8+ #4
+  Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
+  Call Trace:
+    <IRQ>
+    dump_stack+0x5c/0x7d
+    should_fail+0x148/0x170
+    nvme_should_fail+0x30/0x60 [nvme_core]
+    nvme_loop_queue_response+0x84/0x110 [nvme_loop]
+    nvmet_req_complete+0x11/0x40 [nvmet]
+    nvmet_bio_done+0x28/0x40 [nvmet]
+    blk_update_request+0xb0/0x310
+    blk_mq_end_request+0x18/0x60
+    flush_smp_call_function_queue+0x3d/0xf0
+    smp_call_function_single_interrupt+0x2c/0xc0
+    call_function_single_interrupt+0xa2/0xb0
+    </IRQ>
+  RIP: 0010:native_safe_halt+0x2/0x10
+  RSP: 0018:ffffc9000068bec0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff04
+  RAX: ffffffff817a10c0 RBX: ffff88011a3c9680 RCX: 0000000000000000
+  RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
+  RBP: 0000000000000001 R08: 000000008e38c131 R09: 0000000000000000
+  R10: 0000000000000000 R11: 0000000000000000 R12: ffff88011a3c9680
+  R13: ffff88011a3c9680 R14: 0000000000000000 R15: 0000000000000000
+    ? __sched_text_end+0x4/0x4
+    default_idle+0x18/0xf0
+    do_idle+0x150/0x1d0
+    cpu_startup_entry+0x6f/0x80
+    start_secondary+0x187/0x1e0
+    secondary_startup_64+0xa5/0xb0
+
+Example 3: Inject an error into the 10th admin command
+------------------------------------------------------
+
+::
+
+  echo 100 > /sys/kernel/debug/nvme0/fault_inject/probability
+  echo 10 > /sys/kernel/debug/nvme0/fault_inject/space
+  echo 1 > /sys/kernel/debug/nvme0/fault_inject/times
+  nvme reset /dev/nvme0
+
+Expected Result::
+
+  After NVMe controller reset, the reinitialization may or may not succeed.
+  It depends on which admin command is actually forced to fail.
+
+Message from dmesg::
+
+  nvme nvme0: resetting controller
+  FAULT_INJECTION: forcing a failure.
+  name fault_inject, interval 1, probability 100, space 1, times 1
+  CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.2.0-rc2+ #2
+  Hardware name: MSI MS-7A45/B150M MORTAR ARCTIC (MS-7A45), BIOS 1.50 04/25/2017
+  Call Trace:
+   <IRQ>
+   dump_stack+0x63/0x85
+   should_fail+0x14a/0x170
+   nvme_should_fail+0x38/0x80 [nvme_core]
+   nvme_irq+0x129/0x280 [nvme]
+   ? blk_mq_end_request+0xb3/0x120
+   __handle_irq_event_percpu+0x84/0x1a0
+   handle_irq_event_percpu+0x32/0x80
+   handle_irq_event+0x3b/0x60
+   handle_edge_irq+0x7f/0x1a0
+   handle_irq+0x20/0x30
+   do_IRQ+0x4e/0xe0
+   common_interrupt+0xf/0xf
+   </IRQ>
+  RIP: 0010:cpuidle_enter_state+0xc5/0x460
+  Code: ff e8 8f 5f 86 ff 80 7d c7 00 74 17 9c 58 0f 1f 44 00 00 f6 c4 02 0f 85 69 03 00 00 31 ff e8 62 aa 8c ff fb 66 0f 1f 44 00 00 <45> 85 ed 0f 88 37 03 00 00 4c 8b 45 d0 4c 2b 45 b8 48 ba cf f7 53
+  RSP: 0018:ffffffff88c03dd0 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdc
+  RAX: ffff9dac25a2ac80 RBX: ffffffff88d53760 RCX: 000000000000001f
+  RDX: 0000000000000000 RSI: 000000002d958403 RDI: 0000000000000000
+  RBP: ffffffff88c03e18 R08: fffffff75e35ffb7 R09: 00000a49a56c0b48
+  R10: ffffffff88c03da0 R11: 0000000000001b0c R12: ffff9dac25a34d00
+  R13: 0000000000000006 R14: 0000000000000006 R15: ffffffff88d53760
+   cpuidle_enter+0x2e/0x40
+   call_cpuidle+0x23/0x40
+   do_idle+0x201/0x280
+   cpu_startup_entry+0x1d/0x20
+   rest_init+0xaa/0xb0
+   arch_call_rest_init+0xe/0x1b
+   start_kernel+0x51c/0x53b
+   x86_64_start_reservations+0x24/0x26
+   x86_64_start_kernel+0x74/0x77
+   secondary_startup_64+0xa4/0xb0
+  nvme nvme0: Could not set queue count (16385)
+  nvme nvme0: IO queues not created