diff options
| author | Paul E. McKenney <paulmck@linux.vnet.ibm.com> | 2010-02-25 14:06:47 -0800 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2010-02-26 08:20:46 +0100 |
| commit | d9f1bb6ad7fc53c406706f47858dd5ff030b14a3 (patch) | |
| tree | 4af519d68b396e372e6a5afbb5e968de3bacd123 /kernel/rcupdate.c | |
| parent | 056ba4a9bea5f32781a36b797c562fb731e5eaa6 (diff) | |
| download | linux-d9f1bb6ad7fc53c406706f47858dd5ff030b14a3.tar.bz2 | |
rcu: Make rcu_read_lock_sched_held() take boot time into account
Before the scheduler starts, all tasks are non-preemptible by
definition. So, during that time, rcu_read_lock_sched_held()
needs to always return "true". This patch makes that be so.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267135607-7056-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcupdate.c')
| -rw-r--r-- | kernel/rcupdate.c | 18 |
1 files changed, 18 insertions, 0 deletions
diff --git a/kernel/rcupdate.c b/kernel/rcupdate.c index 033cb55c26df..7bfa004572b1 100644 --- a/kernel/rcupdate.c +++ b/kernel/rcupdate.c @@ -44,6 +44,7 @@ #include <linux/cpu.h> #include <linux/mutex.h> #include <linux/module.h> +#include <linux/kernel_stat.h> #ifdef CONFIG_DEBUG_LOCK_ALLOC static struct lock_class_key rcu_lock_key; @@ -62,6 +63,23 @@ struct lockdep_map rcu_sched_lock_map = EXPORT_SYMBOL_GPL(rcu_sched_lock_map); #endif +int rcu_scheduler_active __read_mostly; + +/* + * This function is invoked towards the end of the scheduler's initialization + * process. Before this is called, the idle task might contain + * RCU read-side critical sections (during which time, this idle + * task is booting the system). After this function is called, the + * idle tasks are prohibited from containing RCU read-side critical + * sections. + */ +void rcu_scheduler_starting(void) +{ + WARN_ON(num_online_cpus() != 1); + WARN_ON(nr_context_switches() > 0); + rcu_scheduler_active = 1; +} + /* * Awaken the corresponding synchronize_rcu() instance now that a * grace period has elapsed. |