rcu: Add a module parameter to force use of expedited RCU primitives
There have been some embedded applications that would benefit from
use of expedited grace-period primitives. In some ways, this is
similar to synchronize_net() doing either a normal or an expedited
grace period depending on lock state, but with control outside of
the kernel.
This commit therefore adds rcu_expedited boot and sysfs parameters
that cause the kernel to substitute expedited primitives for the
normal grace-period primitives.
[ paulmck: Add trace/event/rcu.h to kernel/srcu.c to avoid build error.
Get rid of infinite loop through contention path.]
Signed-off-by: Antti P Miettinen <amiettinen@nvidia.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
diff --git a/kernel/ksysfs.c b/kernel/ksysfs.c
index 4e316e1..8715a79 100644
--- a/kernel/ksysfs.c
+++ b/kernel/ksysfs.c
@@ -141,6 +141,23 @@
}
KERNEL_ATTR_RO(fscaps);
+int rcu_expedited;
+static ssize_t rcu_expedited_show(struct kobject *kobj,
+ struct kobj_attribute *attr, char *buf)
+{
+ return sprintf(buf, "%d\n", rcu_expedited);
+}
+static ssize_t rcu_expedited_store(struct kobject *kobj,
+ struct kobj_attribute *attr,
+ const char *buf, size_t count)
+{
+ if (kstrtoint(buf, 0, &rcu_expedited))
+ return -EINVAL;
+
+ return count;
+}
+KERNEL_ATTR_RW(rcu_expedited);
+
/*
* Make /sys/kernel/notes give the raw contents of our kernel .notes section.
*/
@@ -182,6 +199,7 @@
&kexec_crash_size_attr.attr,
&vmcoreinfo_attr.attr,
#endif
+ &rcu_expedited_attr.attr,
NULL
};