Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull RCU updates from Ingo Molnar:
 "The main RCU related changes in this cycle were:

   - Additional cleanups after RCU flavor consolidation

   - Grace-period forward-progress cleanups and improvements

   - Documentation updates

   - Miscellaneous fixes

   - spin_is_locked() conversions to lockdep

   - SPDX changes to RCU source and header files

   - SRCU updates

   - Torture-test updates, including nolibc updates and moving nolibc to
     tools/include"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (71 commits)
  locking/locktorture: Convert to SPDX license identifier
  linux/torture: Convert to SPDX license identifier
  torture: Convert to SPDX license identifier
  linux/srcu: Convert to SPDX license identifier
  linux/rcutree: Convert to SPDX license identifier
  linux/rcutiny: Convert to SPDX license identifier
  linux/rcu_sync: Convert to SPDX license identifier
  linux/rcu_segcblist: Convert to SPDX license identifier
  linux/rcupdate: Convert to SPDX license identifier
  linux/rcu_node_tree: Convert to SPDX license identifier
  rcu/update: Convert to SPDX license identifier
  rcu/tree: Convert to SPDX license identifier
  rcu/tiny: Convert to SPDX license identifier
  rcu/sync: Convert to SPDX license identifier
  rcu/srcu: Convert to SPDX license identifier
  rcu/rcutorture: Convert to SPDX license identifier
  rcu/rcu_segcblist: Convert to SPDX license identifier
  rcu/rcuperf: Convert to SPDX license identifier
  rcu/rcu.h: Convert to SPDX license identifier
  RCU/torture.txt: Remove section MODULE PARAMETERS
  ...

18 files changed, 864 insertions, 131 deletions

diff --git a/tools/testing/selftests/rcutorture/bin/nolibc.h b/tools/include/nolibc/nolibc.h
index f98f5b92d3eb..1708e9f9f8aa 100644
--- a/tools/testing/selftests/rcutorture/bin/nolibc.h
+++ b/tools/include/nolibc/nolibc.h
@@ -3,7 +3,85 @@
  * Copyright (C) 2017-2018 Willy Tarreau <w@1wt.eu>
  */
 
-/* some archs (at least aarch64) don't expose the regular syscalls anymore by
+/*
+ * This file is designed to be used as a libc alternative for minimal programs
+ * with very limited requirements. It consists of a small number of syscall and
+ * type definitions, and the minimal startup code needed to call main().
+ * All syscalls are declared as static functions so that they can be optimized
+ * away by the compiler when not used.
+ *
+ * Syscalls are split into 3 levels:
+ *   - The lower level is the arch-specific syscall() definition, consisting in
+ *     assembly code in compound expressions. These are called my_syscall0() to
+ *     my_syscall6() depending on the number of arguments. The MIPS
+ *     implementation is limited to 5 arguments. All input arguments are cast
+ *     to a long stored in a register. These expressions always return the
+ *     syscall's return value as a signed long value which is often either a
+ *     pointer or the negated errno value.
+ *
+ *   - The second level is mostly architecture-independent. It is made of
+ *     static functions called sys_<name>() which rely on my_syscallN()
+ *     depending on the syscall definition. These functions are responsible
+ *     for exposing the appropriate types for the syscall arguments (int,
+ *     pointers, etc) and for setting the appropriate return type (often int).
+ *     A few of them are architecture-specific because the syscalls are not all
+ *     mapped exactly the same among architectures. For example, some archs do
+ *     not implement select() and need pselect6() instead, so the sys_select()
+ *     function will have to abstract this.
+ *
+ *   - The third level is the libc call definition. It exposes the lower raw
+ *     sys_<name>() calls in a way that looks like what a libc usually does,
+ *     takes care of specific input values, and of setting errno upon error.
+ *     There can be minor variations compared to standard libc calls. For
+ *     example the open() call always takes 3 args here.
+ *
+ * The errno variable is declared static and unused. This way it can be
+ * optimized away if not used. However this means that a program made of
+ * multiple C files may observe different errno values (one per C file). For
+ * the type of programs this project targets it usually is not a problem. The
+ * resulting program may even be reduced by defining the NOLIBC_IGNORE_ERRNO
+ * macro, in which case the errno value will never be assigned.
+ *
+ * Some stdint-like integer types are defined. These are valid on all currently
+ * supported architectures, because signs are enforced, ints are assumed to be
+ * 32 bits, longs the size of a pointer and long long 64 bits. If more
+ * architectures have to be supported, this may need to be adapted.
+ *
+ * Some macro definitions like the O_* values passed to open(), and some
+ * structures like the sys_stat struct depend on the architecture.
+ *
+ * The definitions start with the architecture-specific parts, which are picked
+ * based on what the compiler knows about the target architecture, and are
+ * completed with the generic code. Since it is the compiler which sets the
+ * target architecture, cross-compiling normally works out of the box without
+ * having to specify anything.
+ *
+ * Finally some very common libc-level functions are provided. It is the case
+ * for a few functions usually found in string.h, ctype.h, or stdlib.h. Nothing
+ * is currently provided regarding stdio emulation.
+ *
+ * The macro NOLIBC is always defined, so that it is possible for a program to
+ * check this macro to know if it is being built against and decide to disable
+ * some features or simply not to include some standard libc files.
+ *
+ * Ideally this file should be split in multiple files for easier long term
+ * maintenance, but provided as a single file as it is now, it's quite
+ * convenient to use. Maybe some variations involving a set of includes at the
+ * top could work.
+ *
+ * A simple static executable may be built this way :
+ *      $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
+ *            -static -include nolibc.h -lgcc -o hello hello.c
+ *
+ * A very useful calling convention table may be found here :
+ *      http://man7.org/linux/man-pages/man2/syscall.2.html
+ *
+ * This doc is quite convenient though not necessarily up to date :
+ *      https://w3challs.com/syscalls/
+ *
+ */
+
+/* Some archs (at least aarch64) don't expose the regular syscalls anymore by
  * default, either because they have an "_at" replacement, or because there are
  * more modern alternatives. For now we'd rather still use them.
  */
@@ -19,18 +97,6 @@
 
 #define NOLIBC
 
-/* Build a static executable this way :
- *      $ gcc -fno-asynchronous-unwind-tables -fno-ident -s -Os -nostdlib \
- *            -static -include nolibc.h -lgcc -o hello hello.c
- *
- * Useful calling convention table found here :
- *      http://man7.org/linux/man-pages/man2/syscall.2.html
- *
- * This doc is even better :
- *      https://w3challs.com/syscalls/
- */
-
-
 /* this way it will be removed if unused */
 static int errno;
 
@@ -81,9 +147,9 @@ typedef   signed long        time_t;
 
 /* for poll() */
 struct pollfd {
-    int fd;
-    short int events;
-    short int revents;
+	int fd;
+	short int events;
+	short int revents;
 };
 
 /* for select() */
@@ -239,7 +305,7 @@ struct stat {
 		"syscall\n"                                                   \
 		: "=a" (_ret)                                                 \
 		: "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })
@@ -255,7 +321,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1),                                                 \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })
@@ -272,7 +338,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1), "r"(_arg2),                                     \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })
@@ -290,7 +356,7 @@ struct stat {
 		: "=a" (_ret)                                                 \
 		: "r"(_arg1), "r"(_arg2), "r"(_arg3),                         \
 		  "0"(_num)                                                   \
-		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"                                \
+		: "rcx", "r8", "r9", "r10", "r11", "memory", "cc"             \
 	);                                                                    \
 	_ret;                                                                 \
 })
@@ -1006,7 +1072,7 @@ struct sys_stat_struct {
 		: "=r"(_num), "=r"(_arg4)                                     \
 		: "r"(_num)                                                   \
 		: "memory", "cc", "at", "v1", "hi", "lo",                     \
-									      \
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9"  \
 	);                                                                    \
 	_arg4 ? -_num : _num;                                                 \
 })
@@ -1025,7 +1091,7 @@ struct sys_stat_struct {
 		: "0"(_num),                                                  \
 		  "r"(_arg1)                                                  \
 		: "memory", "cc", "at", "v1", "hi", "lo",                     \
-									      \
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9"  \
 	);                                                                    \
 	_arg4 ? -_num : _num;                                                 \
 })
@@ -1045,7 +1111,7 @@ struct sys_stat_struct {
 		: "0"(_num),                                                  \
 		  "r"(_arg1), "r"(_arg2)                                      \
 		: "memory", "cc", "at", "v1", "hi", "lo",                     \
-									      \
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9"  \
 	);                                                                    \
 	_arg4 ? -_num : _num;                                                 \
 })
@@ -1066,7 +1132,7 @@ struct sys_stat_struct {
 		: "0"(_num),                                                  \
 		  "r"(_arg1), "r"(_arg2), "r"(_arg3)                          \
 		: "memory", "cc", "at", "v1", "hi", "lo",                     \
-									      \
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9"  \
 	);                                                                    \
 	_arg4 ? -_num : _num;                                                 \
 })
@@ -1087,7 +1153,7 @@ struct sys_stat_struct {
 		: "0"(_num),                                                  \
 		  "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4)              \
 		: "memory", "cc", "at", "v1", "hi", "lo",                     \
-									      \
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9"  \
 	);                                                                    \
 	_arg4 ? -_num : _num;                                                 \
 })
@@ -1110,7 +1176,7 @@ struct sys_stat_struct {
 		: "0"(_num),                                                  \
 		  "r"(_arg1), "r"(_arg2), "r"(_arg3), "r"(_arg4), "r"(_arg5)  \
 		: "memory", "cc", "at", "v1", "hi", "lo",                     \
-									      \
+		  "t0", "t1", "t2", "t3", "t4", "t5", "t6", "t7", "t8", "t9"  \
 	);                                                                    \
 	_arg4 ? -_num : _num;                                                 \
 })
diff --git a/tools/memory-model/.gitignore b/tools/memory-model/.gitignore
new file mode 100644
index 000000000000..b1d34c52f3c3
--- /dev/null
+++ b/tools/memory-model/.gitignore
@@ -0,0 +1 @@
+litmus
diff --git a/tools/memory-model/README b/tools/memory-model/README
index acf9077cffaa..0f2c366518c6 100644
--- a/tools/memory-model/README
+++ b/tools/memory-model/README
@@ -156,6 +156,8 @@ lock.cat
 README
 	This file.
 
+scripts	Various scripts, see scripts/README.
+
 
 ===========
 LIMITATIONS
diff --git a/tools/memory-model/linux-kernel.bell b/tools/memory-model/linux-kernel.bell
index b84fb2f67109..796513362c05 100644
--- a/tools/memory-model/linux-kernel.bell
+++ b/tools/memory-model/linux-kernel.bell
@@ -29,7 +29,8 @@ enum Barriers = 'wmb (*smp_wmb*) ||
 		'sync-rcu (*synchronize_rcu*) ||
 		'before-atomic (*smp_mb__before_atomic*) ||
 		'after-atomic (*smp_mb__after_atomic*) ||
-		'after-spinlock (*smp_mb__after_spinlock*)
+		'after-spinlock (*smp_mb__after_spinlock*) ||
+		'after-unlock-lock (*smp_mb__after_unlock_lock*)
 instructions F[Barriers]
 
 (* Compute matching pairs of nested Rcu-lock and Rcu-unlock *)
diff --git a/tools/memory-model/linux-kernel.cat b/tools/memory-model/linux-kernel.cat
index 882fc33274ac..8f23c74a96fd 100644
--- a/tools/memory-model/linux-kernel.cat
+++ b/tools/memory-model/linux-kernel.cat
@@ -30,7 +30,9 @@ let wmb = [W] ; fencerel(Wmb) ; [W]
 let mb = ([M] ; fencerel(Mb) ; [M]) |
 	([M] ; fencerel(Before-atomic) ; [RMW] ; po? ; [M]) |
 	([M] ; po? ; [RMW] ; fencerel(After-atomic) ; [M]) |
-	([M] ; po? ; [LKW] ; fencerel(After-spinlock) ; [M])
+	([M] ; po? ; [LKW] ; fencerel(After-spinlock) ; [M]) |
+	([M] ; po ; [UL] ; (co | po) ; [LKW] ;
+		fencerel(After-unlock-lock) ; [M])
 let gp = po ; [Sync-rcu] ; po?
 
 let strong-fence = mb | gp
diff --git a/tools/memory-model/linux-kernel.def b/tools/memory-model/linux-kernel.def
index 6fa3eb28d40b..b27911cc087d 100644
--- a/tools/memory-model/linux-kernel.def
+++ b/tools/memory-model/linux-kernel.def
@@ -23,6 +23,7 @@ smp_wmb() { __fence{wmb}; }
 smp_mb__before_atomic() { __fence{before-atomic}; }
 smp_mb__after_atomic() { __fence{after-atomic}; }
 smp_mb__after_spinlock() { __fence{after-spinlock}; }
+smp_mb__after_unlock_lock() { __fence{after-unlock-lock}; }
 
 // Exchange
 xchg(X,V)  __xchg{mb}(X,V)
diff --git a/tools/memory-model/scripts/README b/tools/memory-model/scripts/README
new file mode 100644
index 000000000000..29375a1fbbfa
--- /dev/null
+++ b/tools/memory-model/scripts/README
@@ -0,0 +1,70 @@
+			============
+			LKMM SCRIPTS
+			============
+
+
+These scripts are run from the tools/memory-model directory.
+
+checkalllitmus.sh
+
+	Run all litmus tests in the litmus-tests directory, checking
+	the results against the expected results recorded in the
+	"Result:" comment lines.
+
+checkghlitmus.sh
+
+	Run all litmus tests in the https://github.com/paulmckrcu/litmus
+	archive that are C-language and that have "Result:" comment lines
+	documenting expected results, comparing the actual results to
+	those expected.
+
+checklitmushist.sh
+
+	Run all litmus tests having .litmus.out files from previous
+	initlitmushist.sh or newlitmushist.sh runs, comparing the
+	herd output to that of the original runs.
+
+checklitmus.sh
+
+	Check a single litmus test against its "Result:" expected result.
+
+cmplitmushist.sh
+
+	Compare output from two different runs of the same litmus tests,
+	with the absolute pathnames of the tests to run provided one
+	name per line on standard input.  Not normally run manually,
+	provided instead for use by other scripts.
+
+initlitmushist.sh
+
+	Run all litmus tests having no more than the specified number
+	of processes given a specified timeout, recording the results
+	in .litmus.out files.
+
+judgelitmus.sh
+
+	Given a .litmus file and its .litmus.out herd output, check the
+	.litmus.out file against the .litmus file's "Result:" comment to
+	judge whether the test ran correctly.  Not normally run manually,
+	provided instead for use by other scripts.
+
+newlitmushist.sh
+
+	For all new or updated litmus tests having no more than the
+	specified number of processes given a specified timeout, run
+	and record the results in .litmus.out files.
+
+parseargs.sh
+
+	Parse command-line arguments.  Not normally run manually,
+	provided instead for use by other scripts.
+
+runlitmushist.sh
+
+	Run the litmus tests whose absolute pathnames are provided one
+	name per line on standard input.  Not normally run manually,
+	provided instead for use by other scripts.
+
+README
+
+	This file
diff --git a/tools/memory-model/scripts/checkalllitmus.sh b/tools/memory-model/scripts/checkalllitmus.sh
index ca528f9a24d4..b35fcd61ecf6 100755
--- a/tools/memory-model/scripts/checkalllitmus.sh
+++ b/tools/memory-model/scripts/checkalllitmus.sh
@@ -1,42 +1,27 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
 #
-# Run herd tests on all .litmus files in the specified directory (which
-# defaults to litmus-tests) and check each file's result against a "Result:"
-# comment within that litmus test.  If the verification result does not
-# match that specified in the litmus test, this script prints an error
-# message prefixed with "^^^".  It also outputs verification results to
-# a file whose name is that of the specified litmus test, but with ".out"
-# appended.
+# Run herd tests on all .litmus files in the litmus-tests directory
+# and check each file's result against a "Result:" comment within that
+# litmus test.  If the verification result does not match that specified
+# in the litmus test, this script prints an error message prefixed with
+# "^^^".  It also outputs verification results to a file whose name is
+# that of the specified litmus test, but with ".out" appended.
 #
 # Usage:
-#	checkalllitmus.sh [ directory ]
+#	checkalllitmus.sh
 #
-# The LINUX_HERD_OPTIONS environment variable may be used to specify
-# arguments to herd, whose default is defined by the checklitmus.sh script.
-# Thus, one would normally run this in the directory containing the memory
-# model, specifying the pathname of the litmus test to check.
+# Run this in the directory containing the memory model.
 #
 # This script makes no attempt to run the litmus tests concurrently.
 #
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, you can access it online at
-# http://www.gnu.org/licenses/gpl-2.0.html.
-#
 # Copyright IBM Corporation, 2018
 #
 # Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 
-litmusdir=${1-litmus-tests}
+. scripts/parseargs.sh
+
+litmusdir=litmus-tests
 if test -d "$litmusdir" -a -r "$litmusdir" -a -x "$litmusdir"
 then
 	:
@@ -45,6 +30,14 @@ else
 	exit 255
 fi
 
+# Create any new directories that have appeared in the github litmus
+# repo since the last run.
+if test "$LKMM_DESTDIR" != "."
+then
+	find $litmusdir -type d -print |
+	( cd "$LKMM_DESTDIR"; sed -e 's/^/mkdir -p /' | sh )
+fi
+
 # Find the checklitmus script.  If it is not where we expect it, then
 # assume that the caller has the PATH environment variable set
 # appropriately.
@@ -57,7 +50,7 @@ fi
 
 # Run the script on all the litmus tests in the specified directory
 ret=0
-for i in litmus-tests/*.litmus
+for i in $litmusdir/*.litmus
 do
 	if ! $clscript $i
 	then
@@ -66,8 +59,8 @@ do
 done
 if test "$ret" -ne 0
 then
-	echo " ^^^ VERIFICATION MISMATCHES"
+	echo " ^^^ VERIFICATION MISMATCHES" 1>&2
 else
-	echo All litmus tests verified as was expected.
+	echo All litmus tests verified as was expected. 1>&2
 fi
 exit $ret
diff --git a/tools/memory-model/scripts/checkghlitmus.sh b/tools/memory-model/scripts/checkghlitmus.sh
new file mode 100644
index 000000000000..6589fbb6f653
--- /dev/null
+++ b/tools/memory-model/scripts/checkghlitmus.sh
@@ -0,0 +1,65 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Runs the C-language litmus tests having a maximum number of processes
+# to run, defaults to 6.
+#
+# sh checkghlitmus.sh
+#
+# Run from the Linux kernel tools/memory-model directory.  See the
+# parseargs.sh scripts for arguments.
+
+. scripts/parseargs.sh
+
+T=/tmp/checkghlitmus.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
+
+# Clone the repository if it is not already present.
+if test -d litmus
+then
+	:
+else
+	git clone https://github.com/paulmckrcu/litmus
+	( cd litmus; git checkout origin/master )
+fi
+
+# Create any new directories that have appeared in the github litmus
+# repo since the last run.
+if test "$LKMM_DESTDIR" != "."
+then
+	find litmus -type d -print |
+	( cd "$LKMM_DESTDIR"; sed -e 's/^/mkdir -p /' | sh )
+fi
+
+# Create a list of the C-language litmus tests previously run.
+( cd $LKMM_DESTDIR; find litmus -name '*.litmus.out' -print ) |
+	sed -e 's/\.out$//' |
+	xargs -r egrep -l '^ \* Result: (Never|Sometimes|Always|DEADLOCK)' |
+	xargs -r grep -L "^P${LKMM_PROCS}"> $T/list-C-already
+
+# Create a list of C-language litmus tests with "Result:" commands and
+# no more than the specified number of processes.
+find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C
+xargs < $T/list-C -r egrep -l '^ \* Result: (Never|Sometimes|Always|DEADLOCK)' > $T/list-C-result
+xargs < $T/list-C-result -r grep -L "^P${LKMM_PROCS}" > $T/list-C-result-short
+
+# Form list of tests without corresponding .litmus.out files
+sort $T/list-C-already $T/list-C-result-short | uniq -u > $T/list-C-needed
+
+# Run any needed tests.
+if scripts/runlitmushist.sh < $T/list-C-needed > $T/run.stdout 2> $T/run.stderr
+then
+	errs=
+else
+	errs=1
+fi
+
+sed < $T/list-C-result-short -e 's,^,scripts/judgelitmus.sh ,' |
+	sh > $T/judge.stdout 2> $T/judge.stderr
+
+if test -n "$errs"
+then
+	cat $T/run.stderr 1>&2
+fi
+grep '!!!' $T/judge.stdout
diff --git a/tools/memory-model/scripts/checklitmus.sh b/tools/memory-model/scripts/checklitmus.sh
index bf12a75c0719..dd08801a30b0 100755
--- a/tools/memory-model/scripts/checklitmus.sh
+++ b/tools/memory-model/scripts/checklitmus.sh
@@ -1,40 +1,24 @@
 #!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
 #
-# Run a herd test and check the result against a "Result:" comment within
-# the litmus test.  If the verification result does not match that specified
-# in the litmus test, this script prints an error message prefixed with
-# "^^^" and exits with a non-zero status.  It also outputs verification
+# Run a herd test and invokes judgelitmus.sh to check the result against
+# a "Result:" comment within the litmus test.  It also outputs verification
 # results to a file whose name is that of the specified litmus test, but
 # with ".out" appended.
 #
 # Usage:
 #	checklitmus.sh file.litmus
 #
-# The LINUX_HERD_OPTIONS environment variable may be used to specify
-# arguments to herd, which default to "-conf linux-kernel.cfg".  Thus,
-# one would normally run this in the directory containing the memory model,
-# specifying the pathname of the litmus test to check.
-#
-# This program is free software; you can redistribute it and/or modify
-# it under the terms of the GNU General Public License as published by
-# the Free Software Foundation; either version 2 of the License, or
-# (at your option) any later version.
-#
-# This program is distributed in the hope that it will be useful,
-# but WITHOUT ANY WARRANTY; without even the implied warranty of
-# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
-# GNU General Public License for more details.
-#
-# You should have received a copy of the GNU General Public License
-# along with this program; if not, you can access it online at
-# http://www.gnu.org/licenses/gpl-2.0.html.
+# Run this in the directory containing the memory model, specifying the
+# pathname of the litmus test to check.  The caller is expected to have
+# properly set up the LKMM environment variables.
 #
 # Copyright IBM Corporation, 2018
 #
 # Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
 
 litmus=$1
-herdoptions=${LINUX_HERD_OPTIONS--conf linux-kernel.cfg}
+herdoptions=${LKMM_HERD_OPTIONS--conf linux-kernel.cfg}
 
 if test -f "$litmus" -a -r "$litmus"
 then
@@ -43,44 +27,8 @@ else
 	echo ' --- ' error: \"$litmus\" is not a readable file
 	exit 255
 fi
-if grep -q '^ \* Result: ' $litmus
-then
-	outcome=`grep -m 1 '^ \* Result: ' $litmus | awk '{ print $3 }'`
-else
-	outcome=specified
-fi
 
-echo Herd options: $herdoptions > $litmus.out
-/usr/bin/time herd7 -o ~/tmp $herdoptions $litmus >> $litmus.out 2>&1
-grep "Herd options:" $litmus.out
-grep '^Observation' $litmus.out
-if grep -q '^Observation' $litmus.out
-then
-	:
-else
-	cat $litmus.out
-	echo ' ^^^ Verification error'
-	echo ' ^^^ Verification error' >> $litmus.out 2>&1
-	exit 255
-fi
-if test "$outcome" = DEADLOCK
-then
-	echo grep 3 and 4
-	if grep '^Observation' $litmus.out | grep -q 'Never 0 0$'
-	then
-		ret=0
-	else
-		echo " ^^^ Unexpected non-$outcome verification"
-		echo " ^^^ Unexpected non-$outcome verification" >> $litmus.out 2>&1
-		ret=1
-	fi
-elif grep '^Observation' $litmus.out | grep -q $outcome || test "$outcome" = Maybe
-then
-	ret=0
-else
-	echo " ^^^ Unexpected non-$outcome verification"
-	echo " ^^^ Unexpected non-$outcome verification" >> $litmus.out 2>&1
-	ret=1
-fi
-tail -2 $litmus.out | head -1
-exit $ret
+echo Herd options: $herdoptions > $LKMM_DESTDIR/$litmus.out
+/usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $litmus >> $LKMM_DESTDIR/$litmus.out 2>&1
+
+scripts/judgelitmus.sh $litmus
diff --git a/tools/memory-model/scripts/checklitmushist.sh b/tools/memory-model/scripts/checklitmushist.sh
new file mode 100644
index 000000000000..1d210ffb7c8a
--- /dev/null
+++ b/tools/memory-model/scripts/checklitmushist.sh
@@ -0,0 +1,60 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Reruns the C-language litmus tests previously run that match the
+# specified criteria, and compares the result to that of the previous
+# runs from initlitmushist.sh and/or newlitmushist.sh.
+#
+# sh checklitmushist.sh
+#
+# Run from the Linux kernel tools/memory-model directory.
+# See scripts/parseargs.sh for list of arguments.
+#
+# Copyright IBM Corporation, 2018
+#
+# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+. scripts/parseargs.sh
+
+T=/tmp/checklitmushist.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
+
+if test -d litmus
+then
+	:
+else
+	echo Run scripts/initlitmushist.sh first, need litmus repo.
+	exit 1
+fi
+
+# Create the results directory and populate it with subdirectories.
+# The initial output is created here to avoid clobbering the output
+# generated earlier.
+mkdir $T/results
+find litmus -type d -print | ( cd $T/results; sed -e 's/^/mkdir -p /' | sh )
+
+# Create the list of litmus tests already run, then remove those that
+# are excluded by this run's --procs argument.
+( cd $LKMM_DESTDIR; find litmus -name '*.litmus.out' -print ) |
+	sed -e 's/\.out$//' |
+	xargs -r grep -L "^P${LKMM_PROCS}"> $T/list-C-already
+xargs < $T/list-C-already -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
+
+# Redirect output, run tests, then restore destination directory.
+destdir="$LKMM_DESTDIR"
+LKMM_DESTDIR=$T/results; export LKMM_DESTDIR
+scripts/runlitmushist.sh < $T/list-C-short > $T/runlitmushist.sh.out 2>&1
+LKMM_DESTDIR="$destdir"; export LKMM_DESTDIR
+
+# Move the newly generated .litmus.out files to .litmus.out.new files
+# in the destination directory.
+cdir=`pwd`
+ddir=`awk -v c="$cdir" -v d="$LKMM_DESTDIR" \
+	'END { if (d ~ /^\//) print d; else print c "/" d; }' < /dev/null`
+( cd $T/results; find litmus -type f -name '*.litmus.out' -print |
+  sed -e 's,^.*$,cp & '"$ddir"'/&.new,' | sh )
+
+sed < $T/list-C-short -e 's,^,'"$LKMM_DESTDIR/"',' |
+	sh scripts/cmplitmushist.sh
+exit $?
diff --git a/tools/memory-model/scripts/cmplitmushist.sh b/tools/memory-model/scripts/cmplitmushist.sh
new file mode 100644
index 000000000000..0f498aeeccf5
--- /dev/null
+++ b/tools/memory-model/scripts/cmplitmushist.sh
@@ -0,0 +1,87 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Compares .out and .out.new files for each name on standard input,
+# one full pathname per line.  Outputs comparison results followed by
+# a summary.
+#
+# sh cmplitmushist.sh
+
+T=/tmp/cmplitmushist.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
+
+# comparetest oldpath newpath
+perfect=0
+obsline=0
+noobsline=0
+obsresult=0
+badcompare=0
+comparetest () {
+	grep -v 'maxresident)k\|minor)pagefaults\|^Time' $1 > $T/oldout
+	grep -v 'maxresident)k\|minor)pagefaults\|^Time' $2 > $T/newout
+	if cmp -s $T/oldout $T/newout && grep -q '^Observation' $1
+	then
+		echo Exact output match: $2
+		perfect=`expr "$perfect" + 1`
+		return 0
+	fi
+
+	grep '^Observation' $1 > $T/oldout
+	grep '^Observation' $2 > $T/newout
+	if test -s $T/oldout -o -s $T/newout
+	then
+		if cmp -s $T/oldout $T/newout
+		then
+			echo Matching Observation result and counts: $2
+			obsline=`expr "$obsline" + 1`
+			return 0
+		fi
+	else
+		echo Missing Observation line "(e.g., herd7 timeout)": $2
+		noobsline=`expr "$noobsline" + 1`
+		return 0
+	fi
+
+	grep '^Observation' $1 | awk '{ print $3 }' > $T/oldout
+	grep '^Observation' $2 | awk '{ print $3 }' > $T/newout
+	if cmp -s $T/oldout $T/newout
+	then
+		echo Matching Observation Always/Sometimes/Never result: $2
+		obsresult=`expr "$obsresult" + 1`
+		return 0
+	fi
+	echo ' !!!' Result changed: $2
+	badcompare=`expr "$badcompare" + 1`
+	return 1
+}
+
+sed -e 's/^.*$/comparetest &.out &.out.new/' > $T/cmpscript
+. $T/cmpscript > $T/cmpscript.out
+cat $T/cmpscript.out
+
+echo ' ---' Summary: 1>&2
+grep '!!!' $T/cmpscript.out 1>&2
+if test "$perfect" -ne 0
+then
+	echo Exact output matches: $perfect 1>&2
+fi
+if test "$obsline" -ne 0
+then
+	echo Matching Observation result and counts: $obsline 1>&2
+fi
+if test "$noobsline" -ne 0
+then
+	echo Missing Observation line "(e.g., herd7 timeout)": $noobsline 1>&2
+fi
+if test "$obsresult" -ne 0
+then
+	echo Matching Observation Always/Sometimes/Never result: $obsresult 1>&2
+fi
+if test "$badcompare" -ne 0
+then
+	echo "!!!" Result changed: $badcompare 1>&2
+	exit 1
+fi
+
+exit 0
diff --git a/tools/memory-model/scripts/initlitmushist.sh b/tools/memory-model/scripts/initlitmushist.sh
new file mode 100644
index 000000000000..956b6957484d
--- /dev/null
+++ b/tools/memory-model/scripts/initlitmushist.sh
@@ -0,0 +1,68 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Runs the C-language litmus tests matching the specified criteria.
+# Generates the output for each .litmus file into a corresponding
+# .litmus.out file, and does not judge the result.
+#
+# sh initlitmushist.sh
+#
+# Run from the Linux kernel tools/memory-model directory.
+# See scripts/parseargs.sh for list of arguments.
+#
+# This script can consume significant wallclock time and CPU, especially as
+# the value of --procs rises.  On a four-core (eight hardware threads)
+# 2.5GHz x86 with a one-minute per-run timeout:
+#
+# --procs wallclock CPU		timeouts	tests
+#	1 0m11.241s 0m1.086s           0	   19
+#	2 1m12.598s 2m8.459s           2	  393
+#	3 1m30.007s 6m2.479s           4	 2291
+#	4 3m26.042s 18m5.139s	       9	 3217
+#	5 4m26.661s 23m54.128s	      13	 3784
+#	6 4m41.900s 26m4.721s         13	 4352
+#	7 5m51.463s 35m50.868s        13	 4626
+#	8 10m5.235s 68m43.672s        34	 5117
+#	9 15m57.80s 105m58.101s       69	 5156
+#      10 16m14.13s 103m35.009s       69         5165
+#      20 27m48.55s 198m3.286s       156         5269
+#
+# Increasing the timeout on the 20-process run to five minutes increases
+# the runtime to about 90 minutes with the CPU time rising to about
+# 10 hours.  On the other hand, it decreases the number of timeouts to 101.
+#
+# Note that there are historical tests for which herd7 will fail
+# completely, for example, litmus/manual/atomic/C-unlock-wait-00.litmus
+# contains a call to spin_unlock_wait(), which no longer exists in either
+# the kernel or LKMM.
+
+. scripts/parseargs.sh
+
+T=/tmp/initlitmushist.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
+
+if test -d litmus
+then
+	:
+else
+	git clone https://github.com/paulmckrcu/litmus
+	( cd litmus; git checkout origin/master )
+fi
+
+# Create any new directories that have appeared in the github litmus
+# repo since the last run.
+if test "$LKMM_DESTDIR" != "."
+then
+	find litmus -type d -print |
+	( cd "$LKMM_DESTDIR"; sed -e 's/^/mkdir -p /' | sh )
+fi
+
+# Create a list of the C-language litmus tests with no more than the
+# specified number of processes (per the --procs argument).
+find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C
+xargs < $T/list-C -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
+
+scripts/runlitmushist.sh < $T/list-C-short
+
+exit 0
diff --git a/tools/memory-model/scripts/judgelitmus.sh b/tools/memory-model/scripts/judgelitmus.sh
new file mode 100644
index 000000000000..0cc63875e395
--- /dev/null
+++ b/tools/memory-model/scripts/judgelitmus.sh
@@ -0,0 +1,78 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Given a .litmus test and the corresponding .litmus.out file, check
+# the .litmus.out file against the "Result:" comment to judge whether
+# the test ran correctly.
+#
+# Usage:
+#	judgelitmus.sh file.litmus
+#
+# Run this in the directory containing the memory model, specifying the
+# pathname of the litmus test to check.
+#
+# Copyright IBM Corporation, 2018
+#
+# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+litmus=$1
+
+if test -f "$litmus" -a -r "$litmus"
+then
+	:
+else
+	echo ' --- ' error: \"$litmus\" is not a readable file
+	exit 255
+fi
+if test -f "$LKMM_DESTDIR/$litmus".out -a -r "$LKMM_DESTDIR/$litmus".out
+then
+	:
+else
+	echo ' --- ' error: \"$LKMM_DESTDIR/$litmus\".out is not a readable file
+	exit 255
+fi
+if grep -q '^ \* Result: ' $litmus
+then
+	outcome=`grep -m 1 '^ \* Result: ' $litmus | awk '{ print $3 }'`
+else
+	outcome=specified
+fi
+
+grep '^Observation' $LKMM_DESTDIR/$litmus.out
+if grep -q '^Observation' $LKMM_DESTDIR/$litmus.out
+then
+	:
+else
+	echo ' !!! Verification error' $litmus
+	if ! grep -q '!!!' $LKMM_DESTDIR/$litmus.out
+	then
+		echo ' !!! Verification error' >> $LKMM_DESTDIR/$litmus.out 2>&1
+	fi
+	exit 255
+fi
+if test "$outcome" = DEADLOCK
+then
+	if grep '^Observation' $LKMM_DESTDIR/$litmus.out | grep -q 'Never 0 0$'
+	then
+		ret=0
+	else
+		echo " !!! Unexpected non-$outcome verification" $litmus
+		if ! grep -q '!!!' $LKMM_DESTDIR/$litmus.out
+		then
+			echo " !!! Unexpected non-$outcome verification" >> $LKMM_DESTDIR/$litmus.out 2>&1
+		fi
+		ret=1
+	fi
+elif grep '^Observation' $LKMM_DESTDIR/$litmus.out | grep -q $outcome || test "$outcome" = Maybe
+then
+	ret=0
+else
+	echo " !!! Unexpected non-$outcome verification" $litmus
+	if ! grep -q '!!!' $LKMM_DESTDIR/$litmus.out
+	then
+		echo " !!! Unexpected non-$outcome verification" >> $LKMM_DESTDIR/$litmus.out 2>&1
+	fi
+	ret=1
+fi
+tail -2 $LKMM_DESTDIR/$litmus.out | head -1
+exit $ret
diff --git a/tools/memory-model/scripts/newlitmushist.sh b/tools/memory-model/scripts/newlitmushist.sh
new file mode 100644
index 000000000000..991f8f814881
--- /dev/null
+++ b/tools/memory-model/scripts/newlitmushist.sh
@@ -0,0 +1,61 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Runs the C-language litmus tests matching the specified criteria
+# that do not already have a corresponding .litmus.out file, and does
+# not judge the result.
+#
+# sh newlitmushist.sh
+#
+# Run from the Linux kernel tools/memory-model directory.
+# See scripts/parseargs.sh for list of arguments.
+#
+# Copyright IBM Corporation, 2018
+#
+# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+. scripts/parseargs.sh
+
+T=/tmp/newlitmushist.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
+
+if test -d litmus
+then
+	:
+else
+	echo Run scripts/initlitmushist.sh first, need litmus repo.
+	exit 1
+fi
+
+# Create any new directories that have appeared in the github litmus
+# repo since the last run.
+if test "$LKMM_DESTDIR" != "."
+then
+	find litmus -type d -print |
+	( cd "$LKMM_DESTDIR"; sed -e 's/^/mkdir -p /' | sh )
+fi
+
+# Create a list of the C-language litmus tests previously run.
+( cd $LKMM_DESTDIR; find litmus -name '*.litmus.out' -print ) |
+	sed -e 's/\.out$//' |
+	xargs -r grep -L "^P${LKMM_PROCS}"> $T/list-C-already
+
+# Form full list of litmus tests with no more than the specified
+# number of processes (per the --procs argument).
+find litmus -name '*.litmus' -exec grep -l -m 1 "^C " {} \; > $T/list-C-all
+xargs < $T/list-C-all -r grep -L "^P${LKMM_PROCS}" > $T/list-C-short
+
+# Form list of new tests.  Note: This does not handle litmus-test deletion!
+sort $T/list-C-already $T/list-C-short | uniq -u > $T/list-C-new
+
+# Form list of litmus tests that have changed since the last run.
+sed < $T/list-C-short -e 's,^.*$,if test & -nt '"$LKMM_DESTDIR"'/&.out; then echo &; fi,' > $T/list-C-script
+sh $T/list-C-script > $T/list-C-newer
+
+# Merge the list of new and of updated litmus tests: These must be (re)run.
+sort -u $T/list-C-new $T/list-C-newer > $T/list-C-needed
+
+scripts/runlitmushist.sh < $T/list-C-needed
+
+exit 0
diff --git a/tools/memory-model/scripts/parseargs.sh b/tools/memory-model/scripts/parseargs.sh
new file mode 100644
index 000000000000..859e1d581e05
--- /dev/null
+++ b/tools/memory-model/scripts/parseargs.sh
@@ -0,0 +1,136 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0+
+#
+# the corresponding .litmus.out file, and does not judge the result.
+#
+# . scripts/parseargs.sh
+#
+# Include into other Linux kernel tools/memory-model scripts.
+#
+# Copyright IBM Corporation, 2018
+#
+# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+T=/tmp/parseargs.sh.$$
+mkdir $T
+
+# Initialize one parameter: initparam name default
+initparam () {
+	echo if test -z '"$'$1'"' > $T/s
+	echo then >> $T/s
+	echo	$1='"'$2'"' >> $T/s
+	echo	export $1 >> $T/s
+	echo fi >> $T/s
+	echo $1_DEF='$'$1  >> $T/s
+	. $T/s
+}
+
+initparam LKMM_DESTDIR "."
+initparam LKMM_HERD_OPTIONS "-conf linux-kernel.cfg"
+initparam LKMM_JOBS `getconf _NPROCESSORS_ONLN`
+initparam LKMM_PROCS "3"
+initparam LKMM_TIMEOUT "1m"
+
+scriptname=$0
+
+usagehelp () {
+	echo "Usage $scriptname [ arguments ]"
+	echo "      --destdir path (place for .litmus.out, default by .litmus)"
+	echo "      --herdopts -conf linux-kernel.cfg ..."
+	echo "      --jobs N (number of jobs, default one per CPU)"
+	echo "      --procs N (litmus tests with at most this many processes)"
+	echo "      --timeout N (herd7 timeout (e.g., 10s, 1m, 2hr, 1d, '')"
+	echo "Defaults: --destdir '$LKMM_DESTDIR_DEF' --herdopts '$LKMM_HERD_OPTIONS_DEF' --jobs '$LKMM_JOBS_DEF' --procs '$LKMM_PROCS_DEF' --timeout '$LKMM_TIMEOUT_DEF'"
+	exit 1
+}
+
+usage () {
+	usagehelp 1>&2
+}
+
+# checkarg --argname argtype $# arg mustmatch cannotmatch
+checkarg () {
+	if test $3 -le 1
+	then
+		echo $1 needs argument $2 matching \"$5\"
+		usage
+	fi
+	if echo "$4" | grep -q -e "$5"
+	then
+		:
+	else
+		echo $1 $2 \"$4\" must match \"$5\"
+		usage
+	fi
+	if echo "$4" | grep -q -e "$6"
+	then
+		echo $1 $2 \"$4\" must not match \"$6\"
+		usage
+	fi
+}
+
+while test $# -gt 0
+do
+	case "$1" in
+	--destdir)
+		checkarg --destdir "(path to directory)" "$#" "$2" '.\+' '^--'
+		LKMM_DESTDIR="$2"
+		mkdir $LKMM_DESTDIR > /dev/null 2>&1
+		if ! test -e "$LKMM_DESTDIR"
+		then
+			echo "Cannot create directory --destdir '$LKMM_DESTDIR'"
+			usage
+		fi
+		if test -d "$LKMM_DESTDIR" -a -w "$LKMM_DESTDIR" -a -x "$LKMM_DESTDIR"
+		then
+			:
+		else
+			echo "Directory --destdir '$LKMM_DESTDIR' insufficient permissions to create files"
+			usage
+		fi
+		shift
+		;;
+	--herdopts|--herdopt)
+		checkarg --destdir "(herd options)" "$#" "$2" '.*' '^--'
+		LKMM_HERD_OPTIONS="$2"
+		shift
+		;;
+	-j[1-9]*)
+		njobs="`echo $1 | sed -e 's/^-j//'`"
+		trailchars="`echo $njobs | sed -e 's/[0-9]\+\(.*\)$/\1/'`"
+		if test -n "$trailchars"
+		then
+			echo $1 trailing characters "'$trailchars'"
+			usagehelp
+		fi
+		LKMM_JOBS="`echo $njobs | sed -e 's/^\([0-9]\+\).*$/\1/'`"
+		;;
+	--jobs|--job|-j)
+		checkarg --jobs "(number)" "$#" "$2" '^[1-9][0-9]\+$' '^--'
+		LKMM_JOBS="$2"
+		shift
+		;;
+	--procs|--proc)
+		checkarg --procs "(number)" "$#" "$2" '^[0-9]\+$' '^--'
+		LKMM_PROCS="$2"
+		shift
+		;;
+	--timeout)
+		checkarg --timeout "(timeout spec)" "$#" "$2" '^\([0-9]\+[smhd]\?\|\)$' '^--'
+		LKMM_TIMEOUT="$2"
+		shift
+		;;
+	*)
+		echo Unknown argument $1
+		usage
+		;;
+	esac
+	shift
+done
+if test -z "$LKMM_TIMEOUT"
+then
+	LKMM_TIMEOUT_CMD=""; export LKMM_TIMEOUT_CMD
+else
+	LKMM_TIMEOUT_CMD="timeout $LKMM_TIMEOUT"; export LKMM_TIMEOUT_CMD
+fi
+rm -rf $T
diff --git a/tools/memory-model/scripts/runlitmushist.sh b/tools/memory-model/scripts/runlitmushist.sh
new file mode 100644
index 000000000000..e507f5f933d5
--- /dev/null
+++ b/tools/memory-model/scripts/runlitmushist.sh
@@ -0,0 +1,87 @@
+#!/bin/bash
+# SPDX-License-Identifier: GPL-2.0+
+#
+# Runs the C-language litmus tests specified on standard input, using up
+# to the specified number of CPUs (defaulting to all of them) and placing
+# the results in the specified directory (defaulting to the same place
+# the litmus test came from).
+#
+# sh runlitmushist.sh
+#
+# Run from the Linux kernel tools/memory-model directory.
+# This script uses environment variables produced by parseargs.sh.
+#
+# Copyright IBM Corporation, 2018
+#
+# Author: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
+
+T=/tmp/runlitmushist.sh.$$
+trap 'rm -rf $T' 0
+mkdir $T
+
+if test -d litmus
+then
+	:
+else
+	echo Directory \"litmus\" missing, aborting run.
+	exit 1
+fi
+
+# Prefixes for per-CPU scripts
+for ((i=0;i<$LKMM_JOBS;i++))
+do
+	echo dir="$LKMM_DESTDIR" > $T/$i.sh
+	echo T=$T >> $T/$i.sh
+	echo herdoptions=\"$LKMM_HERD_OPTIONS\" >> $T/$i.sh
+	cat << '___EOF___' >> $T/$i.sh
+	runtest () {
+		echo ' ... ' /usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $1 '>' $dir/$1.out '2>&1'
+		if /usr/bin/time $LKMM_TIMEOUT_CMD herd7 $herdoptions $1 > $dir/$1.out 2>&1
+		then
+			if ! grep -q '^Observation ' $dir/$1.out
+			then
+				echo ' !!! Herd failed, no Observation:' $1
+			fi
+		else
+			exitcode=$?
+			if test "$exitcode" -eq 124
+			then
+				exitmsg="timed out"
+			else
+				exitmsg="failed, exit code $exitcode"
+			fi
+			echo ' !!! Herd' ${exitmsg}: $1
+		fi
+	}
+___EOF___
+done
+
+awk -v q="'" -v b='\\' '
+{
+	print "echo `grep " q "^P[0-9]" b "+(" q " " $0 " | tail -1 | sed -e " q "s/^P" b "([0-9]" b "+" b ")(.*$/" b "1/" q "` " $0
+}' | bash |
+sort -k1n |
+awk -v ncpu=$LKMM_JOBS -v t=$T '
+{
+	print "runtest " $2 >> t "/" NR % ncpu ".sh";
+}
+
+END {
+	for (i = 0; i < ncpu; i++) {
+		print "sh " t "/" i ".sh > " t "/" i ".sh.out 2>&1 &";
+		close(t "/" i ".sh");
+	}
+	print "wait";
+}' | sh
+cat $T/*.sh.out
+if grep -q '!!!' $T/*.sh.out
+then
+	echo ' ---' Summary: 1>&2
+	grep '!!!' $T/*.sh.out 1>&2
+	nfail="`grep '!!!' $T/*.sh.out | wc -l`"
+	echo 'Number of failed herd runs (e.g., timeout): ' $nfail 1>&2
+	exit 1
+else
+	echo All runs completed successfully. 1>&2
+	exit 0
+fi
diff --git a/tools/testing/selftests/rcutorture/bin/mkinitrd.sh b/tools/testing/selftests/rcutorture/bin/mkinitrd.sh
index da298394daa2..83552bb007b4 100755
--- a/tools/testing/selftests/rcutorture/bin/mkinitrd.sh
+++ b/tools/testing/selftests/rcutorture/bin/mkinitrd.sh
@@ -40,17 +40,24 @@ mkdir $T
 cat > $T/init << '__EOF___'
 #!/bin/sh
 # Run in userspace a few milliseconds every second.  This helps to
-# exercise the NO_HZ_FULL portions of RCU.
+# exercise the NO_HZ_FULL portions of RCU.  The 192 instances of "a" was
+# empirically shown to give a nice multi-millisecond burst of user-mode
+# execution on a 2GHz CPU, as desired.  Modern CPUs will vary from a
+# couple of milliseconds up to perhaps 100 milliseconds, which is an
+# acceptable range.
+#
+# Why not calibrate an exact delay?  Because within this initrd, we
+# are restricted to Bourne-shell builtins, which as far as I know do not
+# provide any means of obtaining a fine-grained timestamp.
+
+a4="a a a a"
+a16="$a4 $a4 $a4 $a4"
+a64="$a16 $a16 $a16 $a16"
+a192="$a64 $a64 $a64"
 while :
 do
 	q=
-	for i in \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a \
-		a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a a
+	for i in $a192
 	do
 		q="$q $i"
 	done
@@ -124,8 +131,8 @@ if echo -e "#if __x86_64__||__i386__||__i486__||__i586__||__i686__" \
    | grep -q '^yes'; then
 	# architecture supported by nolibc
         ${CROSS_COMPILE}gcc -fno-asynchronous-unwind-tables -fno-ident \
-		-nostdlib -include ../bin/nolibc.h -lgcc -s -static -Os \
-		-o init init.c
+		-nostdlib -include ../../../../include/nolibc/nolibc.h \
+		-lgcc -s -static -Os -o init init.c
 else
 	${CROSS_COMPILE}gcc -s -static -Os -o init init.c
 fi