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authorLinus Torvalds <torvalds@linux-foundation.org>2009-03-03 14:32:04 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-03-03 14:32:04 -0800
commitb24746c7be75384d182845375c96433d713981bb (patch)
treefdb0371d9e59c94e18c946a88c4aa3bcfa4af9b1 /include
parentf41bf2ab998daaa2ac27348d5813e0ae21c57ded (diff)
parenta682604838763981613e42015cd0e39f2989d6bb (diff)
downloadlinux-2.6.38-lt-ux500-b24746c7be75384d182845375c96433d713981bb.tar.gz
Merge branch 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'core-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: rcu: Teach RCU that idle task is not quiscent state at boot
Diffstat (limited to 'include')
-rw-r--r--include/linux/rcuclassic.h6
-rw-r--r--include/linux/rcupdate.h4
-rw-r--r--include/linux/rcupreempt.h15
-rw-r--r--include/linux/rcutree.h6
4 files changed, 31 insertions, 0 deletions
diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h
index f3f697df1d7..80044a4f3ab 100644
--- a/include/linux/rcuclassic.h
+++ b/include/linux/rcuclassic.h
@@ -181,4 +181,10 @@ extern long rcu_batches_completed_bh(void);
#define rcu_enter_nohz() do { } while (0)
#define rcu_exit_nohz() do { } while (0)
+/* A context switch is a grace period for rcuclassic. */
+static inline int rcu_blocking_is_gp(void)
+{
+ return num_online_cpus() == 1;
+}
+
#endif /* __LINUX_RCUCLASSIC_H */
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index 921340a7b71..528343e6da5 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -52,6 +52,9 @@ struct rcu_head {
void (*func)(struct rcu_head *head);
};
+/* Internal to kernel, but needed by rcupreempt.h. */
+extern int rcu_scheduler_active;
+
#if defined(CONFIG_CLASSIC_RCU)
#include <linux/rcuclassic.h>
#elif defined(CONFIG_TREE_RCU)
@@ -265,6 +268,7 @@ extern void rcu_barrier_sched(void);
/* Internal to kernel */
extern void rcu_init(void);
+extern void rcu_scheduler_starting(void);
extern int rcu_needs_cpu(int cpu);
#endif /* __LINUX_RCUPDATE_H */
diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h
index 3e05c09b54a..74304b4538d 100644
--- a/include/linux/rcupreempt.h
+++ b/include/linux/rcupreempt.h
@@ -142,4 +142,19 @@ static inline void rcu_exit_nohz(void)
#define rcu_exit_nohz() do { } while (0)
#endif /* CONFIG_NO_HZ */
+/*
+ * A context switch is a grace period for rcupreempt synchronize_rcu()
+ * only during early boot, before the scheduler has been initialized.
+ * So, how the heck do we get a context switch? Well, if the caller
+ * invokes synchronize_rcu(), they are willing to accept a context
+ * switch, so we simply pretend that one happened.
+ *
+ * After boot, there might be a blocked or preempted task in an RCU
+ * read-side critical section, so we cannot then take the fastpath.
+ */
+static inline int rcu_blocking_is_gp(void)
+{
+ return num_online_cpus() == 1 && !rcu_scheduler_active;
+}
+
#endif /* __LINUX_RCUPREEMPT_H */
diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index d4368b7975c..a722fb67bb2 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -326,4 +326,10 @@ static inline void rcu_exit_nohz(void)
}
#endif /* CONFIG_NO_HZ */
+/* A context switch is a grace period for rcutree. */
+static inline int rcu_blocking_is_gp(void)
+{
+ return num_online_cpus() == 1;
+}
+
#endif /* __LINUX_RCUTREE_H */