diff options
| author | Steven Rostedt <rostedt@goodmis.org> | 2008-02-29 18:46:50 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@elte.hu> | 2008-02-29 18:46:50 +0100 |
| commit | 2232c2d8e0a6a31061dec311f3d1cf7624bc14f1 (patch) | |
| tree | 1d90ec0b8bd4e3c154e386f005ef596ee25fa53f /include/linux | |
| parent | c0f4133b8f70769bc8dda977feb9a29109d6ccca (diff) | |
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')
| -rw-r--r-- | include/linux/hardirq.h | 10 | ||||
| -rw-r--r-- | include/linux/rcuclassic.h | 3 | ||||
| -rw-r--r-- | include/linux/rcupreempt.h | 22 |
3 files changed, 35 insertions, 0 deletions
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index 2961ec788046..49829988bfa0 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) /* diff --git a/include/linux/rcuclassic.h b/include/linux/rcuclassic.h index 4d6624260b4c..b3dccd68629e 100644 --- a/include/linux/rcuclassic.h +++ b/include/linux/rcuclassic.h @@ -160,5 +160,8 @@ extern void rcu_restart_cpu(int cpu); extern long rcu_batches_completed(void); extern long rcu_batches_completed_bh(void); +#define rcu_enter_nohz() do { } while (0) +#define rcu_exit_nohz() do { } while (0) + #endif /* __KERNEL__ */ #endif /* __LINUX_RCUCLASSIC_H */ diff --git a/include/linux/rcupreempt.h b/include/linux/rcupreempt.h index 60c2a033b19e..01152ed532c8 100644 --- a/include/linux/rcupreempt.h +++ b/include/linux/rcupreempt.h @@ -82,5 +82,27 @@ extern struct rcupreempt_trace *rcupreempt_trace_cpu(int cpu); struct softirq_action; +#ifdef CONFIG_NO_HZ +DECLARE_PER_CPU(long, dynticks_progress_counter); + +static inline void rcu_enter_nohz(void) +{ + __get_cpu_var(dynticks_progress_counter)++; + WARN_ON(__get_cpu_var(dynticks_progress_counter) & 0x1); + mb(); +} + +static inline void rcu_exit_nohz(void) +{ + mb(); + __get_cpu_var(dynticks_progress_counter)++; + WARN_ON(!(__get_cpu_var(dynticks_progress_counter) & 0x1)); +} + +#else /* CONFIG_NO_HZ */ +#define rcu_enter_nohz() do { } while (0) +#define rcu_exit_nohz() do { } while (0) +#endif /* CONFIG_NO_HZ */ + #endif /* __KERNEL__ */ #endif /* __LINUX_RCUPREEMPT_H */ |