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| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-01-23 03:24:08 +0100 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2015-03-11 21:22:38 +0100 |
| commit | 37745d281069682d901f00c0121949a7d224195f (patch) | |
| tree | 0c15fd487faa046a257336b4205572b066873ca7 /kernel | |
| parent | rcu: Detect stalls caused by failure to propagate up rcu_node tree (diff) | |
| download | linux-37745d281069682d901f00c0121949a7d224195f.tar.xz linux-37745d281069682d901f00c0121949a7d224195f.zip | |
rcu: Provide diagnostic option to slow down grace-period initialization
Grace-period initialization normally proceeds quite quickly, so
that it is very difficult to reproduce races against grace-period
initialization. This commit therefore allows grace-period
initialization to be artificially slowed down, increasing
race-reproduction probability. A pair of new Kconfig parameters are
provided, CONFIG_RCU_TORTURE_TEST_SLOW_INIT to enable the slowdowns, and
CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY to specify the number of jiffies
of slowdown to apply. A boot-time parameter named rcutree.gp_init_delay
allows boot-time delay to be specified. By default, no delay will be
applied even if CONFIG_RCU_TORTURE_TEST_SLOW_INIT is set.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/rcu/tree.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 3b7e4133ca99..b42001fd55fb 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -160,6 +160,12 @@ static void invoke_rcu_callbacks(struct rcu_state *rsp, struct rcu_data *rdp); static int kthread_prio = CONFIG_RCU_KTHREAD_PRIO; module_param(kthread_prio, int, 0644); +/* Delay in jiffies for grace-period initialization delays. */ +static int gp_init_delay = IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_INIT) + ? CONFIG_RCU_TORTURE_TEST_SLOW_INIT_DELAY + : 0; +module_param(gp_init_delay, int, 0644); + /* * Track the rcutorture test sequence number and the update version * number within a given test. The rcutorture_testseq is incremented @@ -1769,6 +1775,10 @@ static int rcu_gp_init(struct rcu_state *rsp) raw_spin_unlock_irq(&rnp->lock); cond_resched_rcu_qs(); ACCESS_ONCE(rsp->gp_activity) = jiffies; + if (IS_ENABLED(CONFIG_RCU_TORTURE_TEST_SLOW_INIT) && + gp_init_delay > 0 && + !(rsp->gpnum % (rcu_num_nodes * 10))) + schedule_timeout_uninterruptible(gp_init_delay); } mutex_unlock(&rsp->onoff_mutex); |