torture: Make kvm-recheck-lock.sh tolerate qemu-cmd comments

The qemu-cmd file can contain comments that are not relevant to the
operation of kvm-recheck-lock.sh. This commit therefore strips these
comments before looking for timing information.

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

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>

rcutorture/kvm-recheck-*: Improve result directory readability check

The kvm-recheck-(lock|rcu|rcuperf).sh scripts check whether the
user-specified results directory exists. If not, it prints out error
message that says the specified directory is unreadable. To make the
message more precise, this commit adds a readability check.

Fixes: 2193e1604eac ("rcutorture: Abstract kvm-recheck.sh")

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
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>

torture: Better summary diagnostics for build failures

The reaction of kvm-recheck.sh is obscure at best, and easy to miss
completely. This commit therefore prints "BUG: Build failed" in the
summary at the end of a run. This commit also adds the line of dashes
in cases where performance info is not available, and also avoids
printing nonsense diagnostics in cases where some of the normal test
output is not available. In addition, this commit saves off the .config
file even when the build fails.

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

locktorture: Add kvm-recheck.sh plug-in for locktorture

This commit adds the kvm-recheck-lock.sh plug-in for locktorture to
print out lock-specific progress statistics.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>