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authorPaul E. McKenney <paulmck@linux.ibm.com>2019-04-19 07:38:27 -0700
committerPaul E. McKenney <paulmck@linux.ibm.com>2019-05-28 09:06:09 -0700
commitc682db558e6eec10a711b0a6bcb8c35fd15f6a39 (patch)
tree2ef1e00e69c82e2181a85b6ef32af5741cc2a7f2 /tools
parent3432d765c59ba026de49bd4f1f0c2adeff0e7a16 (diff)
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rcutorture: Add trivial RCU implementation
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@linux.ibm.com> [ paulmck: Fix symbol issue reported by kbuild test robot <lkp@intel.com>. ] [ 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 <andrea.parri@amarulasolutions.com>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL14
-rw-r--r--tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot3
2 files changed, 17 insertions, 0 deletions
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
new file mode 100644
index 000000000000..4d8eb5bfb6f6
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL
@@ -0,0 +1,14 @@
+CONFIG_SMP=y
+CONFIG_NR_CPUS=8
+CONFIG_PREEMPT_NONE=y
+CONFIG_PREEMPT_VOLUNTARY=n
+CONFIG_PREEMPT=n
+CONFIG_HZ_PERIODIC=n
+CONFIG_NO_HZ_IDLE=y
+CONFIG_NO_HZ_FULL=n
+CONFIG_HOTPLUG_CPU=n
+CONFIG_SUSPEND=n
+CONFIG_HIBERNATION=n
+CONFIG_DEBUG_LOCK_ALLOC=n
+CONFIG_DEBUG_OBJECTS_RCU_HEAD=n
+CONFIG_RCU_EXPERT=y
diff --git a/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot
new file mode 100644
index 000000000000..7017f5f5a55f
--- /dev/null
+++ b/tools/testing/selftests/rcutorture/configs/rcu/TRIVIAL.boot
@@ -0,0 +1,3 @@
+rcutorture.torture_type=trivial
+rcutorture.onoff_interval=0
+rcutorture.shuffle_interval=0