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authorSteven Rostedt <rostedt@goodmis.org>2008-02-29 18:46:50 +0100
committerIngo Molnar <mingo@elte.hu>2008-02-29 18:46:50 +0100
commit2232c2d8e0a6a31061dec311f3d1cf7624bc14f1 (patch)
tree1d90ec0b8bd4e3c154e386f005ef596ee25fa53f /include/linux/hardirq.h
parentc0f4133b8f70769bc8dda977feb9a29109d6ccca (diff)
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rcu: add support for dynamic ticks and preempt rcu
The PREEMPT-RCU can get stuck if a CPU goes idle and NO_HZ is set. The idle CPU will not progress the RCU through its grace period and a synchronize_rcu my get stuck. Without this patch I have a box that will not boot when PREEMPT_RCU and NO_HZ are set. That same box boots fine with this patch. This patch comes from the -rt kernel where it has been tested for several months. Signed-off-by: Steven Rostedt <srostedt@redhat.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'include/linux/hardirq.h')
-rw-r--r--include/linux/hardirq.h10
1 files changed, 10 insertions, 0 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index 2961ec78804..49829988bfa 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -109,6 +109,14 @@ static inline void account_system_vtime(struct task_struct *tsk)
}
#endif
+#if defined(CONFIG_PREEMPT_RCU) && defined(CONFIG_NO_HZ)
+extern void rcu_irq_enter(void);
+extern void rcu_irq_exit(void);
+#else
+# define rcu_irq_enter() do { } while (0)
+# define rcu_irq_exit() do { } while (0)
+#endif /* CONFIG_PREEMPT_RCU */
+
/*
* It is safe to do non-atomic ops on ->hardirq_context,
* because NMI handlers may not preempt and the ops are
@@ -117,6 +125,7 @@ static inline void account_system_vtime(struct task_struct *tsk)
*/
#define __irq_enter() \
do { \
+ rcu_irq_enter(); \
account_system_vtime(current); \
add_preempt_count(HARDIRQ_OFFSET); \
trace_hardirq_enter(); \
@@ -135,6 +144,7 @@ extern void irq_enter(void);
trace_hardirq_exit(); \
account_system_vtime(current); \
sub_preempt_count(HARDIRQ_OFFSET); \
+ rcu_irq_exit(); \
} while (0)
/*