kernel.git/tools/testing/selftests/rcutorture, branch linux-5.4.y

rcutorture: Test TREE03 with the threadirqs kernel boot parameter

2019-08-01T21:30:22Z

Since commit 05f415715ce45 ("rcu: Speed up expedited GPs when interrupting RCU reader") in v5.0 and through v5.1, booting with the threadirqs kernel boot parameter caused self-deadlocks, which can be reproduced using the following command on an 8-CPU system: tools/testing/selftests/rcutorture/bin/kvm.sh --duration 5 --configs "TREE03" --bootargs "threadirqs" This commit therefore adds the threadirqs kernel boot parameter to the TREE03 rcutorture scenario in order to more quickly detect future similar bugs. Link: http://lkml.kernel.org/r/20190626135447.y24mvfuid5fifwjc@linutronix.de Signed-off-by: Paul E. McKenney Cc: Sebastian Andrzej Siewior Cc: Joel Fernandes

torture: Expand last_ts variable in kvm-test-1-run.sh

2019-08-01T21:30:22Z

The kvm-test-1-run.sh script says 'test -z "last_ts"' which always evaluates to true (AKA zero) regardless of the value of the last_ts shell variable. This commit therefore inserts the needed dollar sign ("$"). Signed-off-by: Paul E. McKenney

torture: Suppress propagating trace_printk() warning

2019-05-28T16:06:09Z

When trace_printk() is used, a message including "BUG" is printed to the console, which fools the rcutorture scripting into believing that the corresponding test scenario failed. This commit therefore filters out this particular instance of "BUG", thus avoiding the false-positive test-failure report. Signed-off-by: Paul E. McKenney

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

2019-05-28T16:06:09Z

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 Signed-off-by: Paul E. McKenney

torture: Make --cpus override idleness calculations

2019-05-28T16:06:09Z

Currently, rcutorture will use relatively few CPUs to build the kernel on a busy system, which is often as it should be. However, if the user has used the --cpus argument to dedicate a specified number of CPUs to this torture test, it would be good if the kernel build also made use of them. This commit therefore changes the cpus2use.sh script to use --cpus when specified and to do the idleness calculations otherwise. Signed-off-by: Paul E. McKenney

torture: Run kernel build in source directory

2019-05-28T16:06:09Z

For historical reasons, rcutorture places its build products in a tools/testing/selftests/rcutorture/b1 directory using the O= kbuild command-line argument. However, doing this requires that the source directory be pristine: Not just "make clean" pristine, but instead "make mrproper" (or, equivalently, "make distclean") pristine. Therefore, rcutorture executes a "make mrproper" before each build. Unfortunately, "make mrproper" has the side effect of removing pretty much everything, including tags files and cscope databases, which can be inconvenient to people whose workflow centers around a single source tree. This commit therefore makes rcutorture do the build directly in the source directory, removing the need for "make mrproper". This works because all needed build products are moved to their proper place in the "res" directory immediately after the build completes, so that multiple rcutorture kernels can still run concurrently. Reported-by: Peter Zijlstra Signed-off-by: Paul E. McKenney

torture: Add function graph-tracing cheat sheet

2019-05-28T16:06:09Z

Signed-off-by: Paul E. McKenney

torture: Capture qemu output

2019-05-28T16:06:09Z

Currently qemu output appears on standard output, but is inaccessible later on. This commit therefore captures this output and causes kvm-recheck.sh to output this output if QEMU gave a non-zero non-137 exit code. (And exit code of 137 indicates that QEMU was killed, in which case we want to know about the hang rather than the fact that QEMU was killed.) Signed-off-by: Paul E. McKenney

rcutorture: Tweak kvm options

2019-05-28T16:06:09Z

In one of my rcutorture tests the TSC clocksource got marked unstable due to a large difference in the TSC value. I'm not sure if the guest run for a long time with disabled interrupts or if the host was very busy and didn't schedule the guest for some time. I took a look on the qemu/KVM options and decided to update the options: - Use kvm{32|64} as CPU. We could probably use `host' (like ARM does) for maximum available features but since we don't run any userland I'm not sure if it makes any difference. - Drop the "noapic" option. There is no history why the APIC was disabled, I see no reason for it. Once old qemu versions fade away, we can add "x2apic=on,tsc-deadline=on,hypervisor=on,tsc_adjust=on". - Additional config options. It ensures that the kernel knowns that it runs as a kvm guest and can use virt devices like the kvm-clock as clocksource. The kvm-clock was the main motivation here. - I didn't add a random HW device. It would make the random device ready earlier (not it doesn't complete the initialisation at all) but I doubt that there is any need for this. Signed-off-by: Sebastian Andrzej Siewior [ paulmck: The world is not quite ready for CONFIG_PARAVIRT_SPINLOCKS=y and x2apic, so they are omitted for the time being. ] Signed-off-by: Paul E. McKenney

rcutorture: Add trivial RCU implementation

2019-05-28T16:06:09Z

I have been showing off a trivial RCU implementation for non-preemptive environments for some time now: #define rcu_read_lock() #define rcu_read_unlock() #define rcu_dereference(p) READ_ONCE(p) #define rcu_assign_pointer(p, v) smp_store_release(&(p), (v)) void synchronize_rcu(void) { int cpu; for_each_online_cpu(cpu) sched_setaffinity(current->pid, cpumask_of(cpu)); } Trivial or not, as the old saying goes, "if it ain't tested, it don't work!". This commit therefore adds a "trivial" flavor to rcutorture and a corresponding TRIVIAL test scenario. This variant does not handle CPU hotplug, which is unconditionally enabled on x86 for post-v5.1-rc3 kernels, which is why the TRIVIAL.boot says "rcutorture.onoff_interval=0". This commit actually does handle CONFIG_PREEMPT=y kernels, but only because it turns back the Linux-kernel clock in order to provide these alternative definitions (or the moral equivalent thereof): #define rcu_read_lock() preempt_disable() #define rcu_read_unlock() preempt_enable() In CONFIG_PREEMPT=n kernels without debugging, these are equivalent to empty macros give or take a compiler barrier. However, the have been successfully tested with actual empty macros as well. Signed-off-by: Paul E. McKenney [ paulmck: Fix symbol issue reported by kbuild test robot . ] [ paulmck: Work around sched_setaffinity() issue noted by Andrea Parri. ] [ paulmck: Add rcutorture.shuffle_interval=0 to TRIVIAL.boot to fix interaction with shuffler task noted by Peter Zijlstra. ] Tested-by: Andrea Parri