[GIT PULL] RCU fixes

From: Ingo Molnar
Date: Mon Feb 04 2013 - 13:17:26 EST


Linus,

Please pull the latest core-urgent-for-linus git tree from:

git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-urgent-for-linus

HEAD: d36b7b9643faca8aab8cee8d824f75c800b337ac Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu into core/urgent

Two small fixlets.

Thanks,

Ingo

------------------>
Paul Gortmaker (2):
rcu: Prevent soft-lockup complaints about no-CBs CPUs
rcu: Make rcu_nocb_poll an early_param instead of module_param


Documentation/kernel-parameters.txt | 2 +-
kernel/rcutree_plugin.h | 13 ++++++++++---
2 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 363e348..6c72381 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -2438,7 +2438,7 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
real-time workloads. It can also improve energy
efficiency for asymmetric multiprocessors.

- rcu_nocbs_poll [KNL,BOOT]
+ rcu_nocb_poll [KNL,BOOT]
Rather than requiring that offloaded CPUs
(specified by rcu_nocbs= above) explicitly
awaken the corresponding "rcuoN" kthreads,
diff --git a/kernel/rcutree_plugin.h b/kernel/rcutree_plugin.h
index f6e5ec2..c1cc7e1 100644
--- a/kernel/rcutree_plugin.h
+++ b/kernel/rcutree_plugin.h
@@ -40,8 +40,7 @@
#ifdef CONFIG_RCU_NOCB_CPU
static cpumask_var_t rcu_nocb_mask; /* CPUs to have callbacks offloaded. */
static bool have_rcu_nocb_mask; /* Was rcu_nocb_mask allocated? */
-static bool rcu_nocb_poll; /* Offload kthread are to poll. */
-module_param(rcu_nocb_poll, bool, 0444);
+static bool __read_mostly rcu_nocb_poll; /* Offload kthread are to poll. */
static char __initdata nocb_buf[NR_CPUS * 5];
#endif /* #ifdef CONFIG_RCU_NOCB_CPU */

@@ -2159,6 +2158,13 @@ static int __init rcu_nocb_setup(char *str)
}
__setup("rcu_nocbs=", rcu_nocb_setup);

+static int __init parse_rcu_nocb_poll(char *arg)
+{
+ rcu_nocb_poll = 1;
+ return 0;
+}
+early_param("rcu_nocb_poll", parse_rcu_nocb_poll);
+
/* Is the specified CPU a no-CPUs CPU? */
static bool is_nocb_cpu(int cpu)
{
@@ -2366,10 +2372,11 @@ static int rcu_nocb_kthread(void *arg)
for (;;) {
/* If not polling, wait for next batch of callbacks. */
if (!rcu_nocb_poll)
- wait_event(rdp->nocb_wq, rdp->nocb_head);
+ wait_event_interruptible(rdp->nocb_wq, rdp->nocb_head);
list = ACCESS_ONCE(rdp->nocb_head);
if (!list) {
schedule_timeout_interruptible(1);
+ flush_signals(current);
continue;
}

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