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| author |   Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-04-11 16:41:20 -0700 |
|---|---|---|
| committer | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2018-05-15 10:29:24 -0700 |
| commit | 5fe0a56298e674358ff2740a6288bf21509d895d (patch) | |
| tree | 61a2926d9340b746ff535c954d193e0ae9c6448c /kernel/rcu | |
| parent | rcu: Add accessor macros for the ->need_future_gp[] array (diff) | |
| download | linux-dev-5fe0a56298e674358ff2740a6288bf21509d895d.tar.xz linux-dev-5fe0a56298e674358ff2740a6288bf21509d895d.zip | |
rcu: Make rcu_gp_kthread() check for early-boot activity
The rcu_gp_kthread() function immediately sleeps waiting to be notified
of the need for a new grace period, which currently works because there
are a number of code sequences that will provide the needed wakeup later.
However, some of these code sequences need to acquire the root rcu_node
structure's ->lock, and contention on that lock has started manifesting.
This commit therefore makes rcu_gp_kthread() check for early-boot activity
when it starts up, omitting the initial sleep in that case.
Reported-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Nicholas Piggin <npiggin@gmail.com>
Diffstat (limited to 'kernel/rcu')
| -rw-r--r-- | kernel/rcu/tree.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 79fb99951a0c..497f139056c7 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -2192,6 +2192,12 @@ static int __noreturn rcu_gp_kthread(void *arg) struct rcu_state *rsp = arg; struct rcu_node *rnp = rcu_get_root(rsp); + /* Check for early-boot work. */ + raw_spin_lock_irq_rcu_node(rnp); + if (need_any_future_gp(rnp)) + WRITE_ONCE(rsp->gp_flags, RCU_GP_FLAG_INIT); + raw_spin_unlock_irq_rcu_node(rnp); + rcu_bind_gp_kthread(); for (;;) { |