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2021-07-06scftorture: Avoid false-positive warnings in scftorture_invoker()Paul E. McKenney
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 <paulmck@kernel.org>
2021-01-04scftorture: Add debug output for wrong-CPU warningPaul E. McKenney
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 <paulmck@kernel.org>
2020-11-06scftorture: Add full-test stutter capabilityPaul E. McKenney
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 <clm@fb.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-11-06scftorture: Add an alternative IPI vectorPaul E. McKenney
The scftorture tests currently use only smp_call_function() and friends, which means that these tests cannot locate bugs caused by interactions between different IPI vectors. This commit therefore adds the rescheduling IPI to the mix. Note that this commit permits resched_cpus() only when scftorture is built in. This is a workaround. Longer term, this will use real wakeups rather than resched_cpu(). Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Add cond_resched() to test loopPaul E. McKenney
Although the test loop does randomly delay, which would provide quiescent states and so forth, it is possible for there to be a series of long smp_call_function*() handler runtimes with no delays, which results in softlockup and RCU CPU stall warning messages. This commit therefore inserts a cond_resched() into the main test loop. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Adapt memory-ordering test to UP operationPaul E. McKenney
On uniprocessor systems, smp_call_function() does nothing. This commit therefore avoids complaining about the lack of handler accesses in the single-CPU case where there is no handler. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Block scftorture_invoker() kthreads for offline CPUsPaul E. McKenney
Currently, CPU-hotplug operations might result in all but two of (say) 100 CPUs being offline, which in turn might result in false-positive diagnostics due to overload. This commit therefore causes scftorture_invoker() kthreads for offline CPUs to loop blocking for 200 milliseconds at a time, thus continuously adjusting the number of threads to match the number of online CPUs. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Check unexpected "switch" statement valuePaul E. McKenney
This commit adds a "default" case to the switch statement in scftorture_invoke_one() which contains a WARN_ON_ONCE() and an assignment to ->scfc_out to suppress knock-on warnings. These knock-on warnings could otherwise cause the user to think that there was a memory-ordering problem in smp_call_function() instead of a bug in scftorture.c itself. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Make symbol 'scf_torture_rand' staticWei Yongjun
The sparse tool complains as follows kernel/scftorture.c:124:1: warning: symbol '__pcpu_scope_scf_torture_rand' was not declared. Should it be static? And this per-CPU variable is not used outside of scftorture.c, so this commit marks it static. Reported-by: Hulk Robot <hulkci@huawei.com> Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Prevent compiler from reducing race probabilitiesPaul E. McKenney
Detecting smp_call_function() memory misordering requires close timing, so it is necessary to have the checks immediately before and after the call to the smp_call_function*() function under test. This commit therefore inserts barrier() calls to prevent the compiler from optimizing memory-misordering detection down into the zone of extreme improbability. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Flag errors in torture-compatible mannerPaul E. McKenney
This commit prints error counts on the statistics line and also adds a "!!!" if any of the counters are non-zero. Allocation failures are (somewhat) forgiven, but all other errors result in a "FAILURE" print at the end of the test. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Consolidate scftorture_invoke_one() scf_check initializationPaul E. McKenney
This commit hoists much of the initialization of the scf_check structure out of the switch statement, thus saving a few lines of code. The initialization of the ->scfc_in field remains in each leg of the switch statement in order to more heavily stress memory ordering. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Consolidate scftorture_invoke_one() check and kfree()Paul E. McKenney
This commit moves checking of the ->scfc_out field and the freeing of the scf_check structure down below the end of switch statement, thus saving a few lines of code. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Add smp_call_function() memory-ordering checksPaul E. McKenney
This commit adds checks for memory misordering across calls to and returns from smp_call_function() in the case where the caller waits. Misordering results in a splat. Note that in contrast to smp_call_function_single(), this code does not test memory ordering into the handler in the no-wait case because none of the handlers would be able to free the scf_check structure without introducing heavy synchronization to work out which was last. [ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Add smp_call_function_many() memory-ordering checksPaul E. McKenney
This commit adds checks for memory misordering across calls to and returns from smp_call_function_many() in the case where the caller waits. Misordering results in a splat. Note that in contrast to smp_call_function_single(), this code does not test memory ordering into the handler in the no-wait case because none of the handlers would be able to free the scf_check structure without introducing heavy synchronization to work out which was last. [ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Add smp_call_function_single() memory-ordering checksPaul E. McKenney
This commit adds checks for memory misordering across calls to smp_call_function_single() and also across returns in the case where the caller waits. Misordering results in a splat. [ paulmck: s/GFP_KERNEL/GFP_ATOMIC/ per kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Summarize per-thread statisticsPaul E. McKenney
This commit summarizes the per-thread statistics, providing counts of the number of single, many, and all calls, both no-wait and wait, and, for the single case, the number where the target CPU was offline. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Implement weighted primitive selectionPaul E. McKenney
This commit uses the scftorture.weight* kernel parameters to randomly chooses between smp_call_function_single(), smp_call_function_many(), and smp_call_function(). For each variant, it also randomly chooses whether to invoke it synchronously (wait=1) or asynchronously (wait=0). The percentage weighting for each option are dumped to the console log (search for "scf_sel_dump"). This accumulates statistics, which a later commit will dump out at the end of the run. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2020-08-24scftorture: Add smp_call_function() torture testPaul E. McKenney
This commit adds an smp_call_function() torture test that repeatedly invokes this function and complains if things go badly awry. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>