torture: Use mktemp instead of guessing at unique names

This commit drags the rcutorture scripting kicking and screaming into the
twenty-first century by making use of the BSD-derived mktemp command to
create temporary files and directories. In happy contrast to many of its
ill-behaved predecessors, mktemp seems to actually work reasonably reliably!

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

torture: Make kvm-find-errors.sh report link-time undefined symbols

This commit makes kvm-find-errors.sh check for and report undefined
symbols that are detected at link time.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

torture: Allow standalone kvm-recheck.sh run detect --trust-make

Normally, kvm-recheck.sh is run from kvm.sh, which provides the
TORTURE_TRUST_MAKE environment variable that, if a non-empty string,
indicates that the --trust-make command-line parameter has been passed
to kvm.sh. If there was no --trust-make, kvm-recheck.sh insists
that the Make.out file contain at least one "CC" command. Thus, when
kvm-recheck.sh is run standalone to evaluate a prior --trust-make run,
it will incorrectly insist that a proper kernel build did not happen.

This commit therefore causes kvm-recheck.sh to also search the "log"
file in the top-level results directory for the string "--trust-make".

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

torture: Add --trust-make to suppress "make clean"

The current rcutorture scripts unconditionally do "make clean", which is
a good way of getting the needed testing done despite any imperfections in
Makefile dependency tracking. However, this can be a bit irritating when
repeatedly running a single scenario after small changes, for example,
when debugging a problem that affects only a single scenario. This commit
therefore adds a --trust-make argument that suppresses the "make clean".

Even when using ccache, this speeds up kernel builds by up to almost an
order of magnitude on my laptop.

Reported-by: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

tools/.../rcutorture: Convert to SPDX license identifier

Replace the license boiler plate with a SPDX license identifier.
While in the area, update an email address and add copyright notices.

Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>

torture: Provide TMPDIR environment variable to specify tmpdir

Both rcutorture and locktorture currently place temporary files in /tmp,
in keeping with decades-long tradition. However, sometimes it is useful
to specify an alternative temporary directory, for example, for space
or performance reasons. This commit therefore causes the torture-test
scripting to use the path specified in the TMPDIR environment variable,
or to fall back to traditional /tmp if this variable is not set.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

rcutorture: Make build-output parsing correctly flag RCU's warnings

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

rcutorture: Set executable bit and drop bash from Usage

This commit sets the executable bit on test scripts config2frag.sh
and kvm.sh. Since #!/bin/bash is set in all the scripts, this commit
also drops it from all usage lines because the scripts can now all be
invoked directly.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

rcutorture: Use bash shell for all the test scripts

Some of the scripts encode a default /bin/sh shell. On systems which use
dash as default shell, these scripts fail as they are bash scripts. I
encountered this while testing the sprintf() changes on a Debian system
where dash is the default shell.

This commit changes all such uses to use bash explicitly.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

rcutorture: Stop tracking FSF's postal address

All of the rcutorture scripts has the usual GPL header, which contains
a long-obsolete postal address for FSF. To avoid the need to track the
FSF office's movements, this commit substitutes the URL where GPL may
be found.

Reported-by: Greg KH <gregkh@linuxfoundation.org>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>

rcutorture: Flag errors and warnings with color coding

The output of the rcutorture scripts often requires interpretation, so
this commit simplifies this interpretation by tagging messages as
BUGs (colored red) or WARNINGs (colored yellow).

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>

rcutorture: Add KVM-based test framework

This commit adds the test framework that I used to test RCU under KVM.
This consists of a group of scripts and Kconfig fragments.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Greg KH <gregkh@linuxfoundation.org>