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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 <[email protected]> [ paulmck: Fix symbol issue reported by kbuild test robot <[email protected]>. ] [ 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 <[email protected]>
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Paul E. McKenney
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May 28, 2019
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Original file line number | Diff line number | Diff line change |
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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 |
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Original file line number | Diff line number | Diff line change |
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@@ -0,0 +1,3 @@ | ||
rcutorture.torture_type=trivial | ||
rcutorture.onoff_interval=0 | ||
rcutorture.shuffle_interval=0 |