The scftorture test module's scf_handler() function is supposed to provide
three different distributions of short delays (including "no delay") and
one distribution of long delays, if specified by the scftorture.longwait
module parameter.  However, the second of the two non-zero-wait short delays
is disabled due to the first such delay's "goto out" not being enclosed in
the "then" clause with the "udelay()".

This commit therefore adjusts the code to provide the intended set of
delays.

Fixes: e9d338a0b179 ("scftorture: Add smp_call_function() torture test")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Unconditionally log messages corresponding to errors.

Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Li Zhijian <zhijianx.li@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

There are no longer any users of SCFTORTOUT(), so this commit removes it.

Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Li Zhijian <zhijianx.li@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

Add '\n' to macros to flush message for each call.

Acked-by: Davidlohr Bueso <dbueso@suse.de>
Signed-off-by: Li Zhijian <zhijianx.li@intel.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

When running scftorture as a module, any scf_torture_init() issues will be
reflected in the error code from modprobe or insmod, as the case may be.
However, these error codes are not available when running scftorture
built-in, for example, when using the kvm.sh script.  This commit
therefore adds WARN_ON_ONCE() to allow distinguishing scf_torture_init()
errors when running scftorture built-in.

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

Currently, only those IPIs that invoke scftorture's scf_handler()
IPI handler function are counted.  This means that runs exercising
only scftorture.weight_resched will look like they have made no forward
progress, resulting in "GP HANG" complaints from the rcutorture scripting.
This commit therefore increments the scf_invoked_count per-CPU counter
immediately after calling resched_cpu().

Fixes: 1ac78b49d61d4 ("scftorture: Add an alternative IPI vector")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

The "all zero weights makes no sense" error is emitted even when
scftorture.weight_resched is non-zero because it was left out of
the enclosing "if" condition.  This commit adds it in.

Fixes: 1ac78b49d61d4 ("scftorture: Add an alternative IPI vector")
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

If (say) a 10-hour scftorture run is started, but the module parameters
are so nonsensical that the run doesn't even start, then scftorture will
wait the full ten hours when run built into a guest OS.  This commit
therefore shuts down the system in this case so that the error is reported
immediately instead of ten hours hence.

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

This commit reworks the weighting calculations to allow zero to
be specified to disable a given weight.  For example, specifying the
scftorture.weight_resched=0 kernel boot parameter without specifying a
non-zero value for any of the other scftorture.weight_* parameters would
provide the default weights for the others, but would refrain from doing
any resched-based IPIs.

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

When scftorture finds an error in the module parameters controlling
the relative frequencies of smp_call_function*() variants, it takes an
early exit.  So early that it has not allocated memory to track the
kthreads running the test, which results in a segfault.  This commit
therefore checks for the existence of the memory before attempting
to stop the kthreads that would otherwise have been recorded in that
non-existent memory.

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