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| 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/rcupreempt.h | |
| parent | c0f4133b8f70769bc8dda977feb9a29109d6ccca (diff) | |
| download | linux-2232c2d8e0a6a31061dec311f3d1cf7624bc14f1.tar.gz linux-2232c2d8e0a6a31061dec311f3d1cf7624bc14f1.tar.bz2 linux-2232c2d8e0a6a31061dec311f3d1cf7624bc14f1.zip | |
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/rcupreempt.h')
| -rw-r--r-- | include/linux/rcupreempt.h | 22 |
1 files changed, 22 insertions, 0 deletions
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 */ |