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| author | Paul E. McKenney <paul.mckenney@linaro.org> | 2012-07-02 14:42:01 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2012-09-23 07:42:49 -0700 |
| commit | e3ebfb96f396731ca2d0b108785d5da31b53ab00 (patch) | |
| tree | 7bac429c3cad5f00894746270322d5a4119cea47 /lib | |
| parent | a10d206ef1a83121ab7430cb196e0376a7145b22 (diff) | |
| download | linux-e3ebfb96f396731ca2d0b108785d5da31b53ab00.tar.gz | |
rcu: Add PROVE_RCU_DELAY to provoke difficult races
There have been some recent bugs that were triggered only when preemptible RCU's __rcu_read_unlock() was preempted just after setting ->rcu_read_lock_nesting to INT_MIN, which is a low-probability event. Therefore, reproducing those bugs (to say nothing of gaining confidence in alleged fixes) was quite difficult. This commit therefore creates a new debug-only RCU kernel config option that forces a short delay in __rcu_read_unlock() to increase the probability of those sorts of bugs occurring. Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/Kconfig.debug | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 2403a63b5da5..dacbbe4d7a80 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -629,6 +629,20 @@ config PROVE_RCU_REPEATEDLY Say N if you are unsure. +config PROVE_RCU_DELAY + bool "RCU debugging: preemptible RCU race provocation" + depends on DEBUG_KERNEL && PREEMPT_RCU + default n + help + There is a class of races that involve an unlikely preemption + of __rcu_read_unlock() just after ->rcu_read_lock_nesting has + been set to INT_MIN. This feature inserts a delay at that + point to increase the probability of these races. + + Say Y to increase probability of preemption of __rcu_read_unlock(). + + Say N if you are unsure. + config SPARSE_RCU_POINTER bool "RCU debugging: sparse-based checks for pointer usage" default n |