linux-toradex.git/kernel/scftorture.c, branch v5.16-rc6

scftorture: Warn on individual scf_torture_init() error conditions

2021-09-16T17:27:48+00:00

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

scftorture: Count reschedule IPIs

2021-09-16T17:27:48+00:00

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

scftorture: Account for weight_resched when checking for all zeroes

2021-09-16T17:27:48+00:00

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

scftorture: Shut down if nonsensical arguments given

2021-09-16T17:27:48+00:00

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

scftorture: Allow zero weight to exclude an smp_call_function*() category

2021-09-16T17:25:16+00:00

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

scftorture: Avoid NULL pointer exception on early exit

2021-07-27T18:39:30+00:00

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

scftorture: Add RPC-like IPI tests

2021-07-27T18:39:30+00:00

This commit adds the single_weight_rpc module parameter, which causes the
IPI handler to awaken the IPI sender.  In many scheduler configurations,
this will result in an IPI back to the sender that is likely to be
received at a time when the sender CPU is idle.  The intent is to stress
IPI reception during CPU busy-to-idle transitions.

Signed-off-by: Paul E. McKenney

scftorture: Avoid false-positive warnings in scftorture_invoker()

2021-07-06T19:37:55+00:00

If the call to set_cpus_allowed_ptr() in scftorture_invoker()
fails, a later WARN_ONCE() complains.  But with the advent of
570a752b7a9b ("lib/smp_processor_id: Use is_percpu_thread() instead of
nr_cpus_allowed"), this complaint can be drowned out by complaints from
smp_processor_id().  The rationale for this change is that scftorture's
kthreads are not marked with PF_NO_SETAFFINITY, which means that a system
administrator could change affinity at any time.

However, scftorture is a torture test, and the system administrator might
well have a valid test-the-test reason for changing affinity.  This commit
therefore changes to raw_smp_processor_id() in order to avoid the noise,
and also adds a WARN_ON_ONCE() to the call to set_cpus_allowed_ptr() in
order to directly detect immediate failure.  There is no WARN_ON_ONCE()
within the test loop, allowing human-reflex-based affinity resetting,
if desired.

Signed-off-by: Paul E. McKenney

scftorture: Add debug output for wrong-CPU warning

2021-01-04T21:53:41+00:00

This commit adds the desired CPU, the actual CPU, and nr_cpu_ids to
the wrong-CPU warning in scftorture_invoker(), the better to help with
debugging.

Signed-off-by: Paul E. McKenney

scftorture: Add full-test stutter capability

2020-11-07T01:13:56+00:00

In virtual environments on systems with hardware assist, inter-processor
interrupts must do very different things based on whether the target
vCPU is running or not.  This commit therefore enables torture-test
stuttering to better test these running/not-running transitions.

Suggested-by: Chris Mason 
Signed-off-by: Paul E. McKenney