backport the RCU cpu-hotplug support from .26-rc to .24-rt Signed-off-by: Peter Zijlstra --- kernel/rcupreempt.c | 58 +++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 55 insertions(+), 3 deletions(-) Index: linux-2.6.24.7.noarch/kernel/rcupreempt.c =================================================================== --- linux-2.6.24.7.noarch.orig/kernel/rcupreempt.c +++ linux-2.6.24.7.noarch/kernel/rcupreempt.c @@ -820,6 +820,13 @@ void rcu_offline_cpu_rt(int cpu) smp_mb(); /* Subsequent RCU read-side critical sections */ /* seen -after- acknowledgement. */ } + + __get_cpu_var(rcu_flipctr)[0] += per_cpu(rcu_flipctr, cpu)[0]; + __get_cpu_var(rcu_flipctr)[1] += per_cpu(rcu_flipctr, cpu)[1]; + + per_cpu(rcu_flipctr, cpu)[0] = 0; + per_cpu(rcu_flipctr, cpu)[1] = 0; + cpu_clear(cpu, rcu_cpu_online_map); spin_unlock_irqrestore(&rcu_ctrlblk.fliplock, oldirq); @@ -833,8 +840,9 @@ void rcu_offline_cpu_rt(int cpu) * fix. */ + local_irq_save(oldirq); rdp = RCU_DATA_ME(); - spin_lock_irqsave(&rdp->lock, oldirq); + spin_lock(&rdp->lock); *rdp->nexttail = list; if (list) rdp->nexttail = tail; @@ -866,9 +874,11 @@ void rcu_process_callbacks_rt(struct sof { unsigned long flags; struct rcu_head *next, *list; - struct rcu_data *rdp = RCU_DATA_ME(); + struct rcu_data *rdp; - spin_lock_irqsave(&rdp->lock, flags); + local_irq_save(flags); + rdp = RCU_DATA_ME(); + spin_lock(&rdp->lock); list = rdp->donelist; if (list == NULL) { spin_unlock_irqrestore(&rdp->lock, flags); @@ -951,6 +961,32 @@ int rcu_pending_rt(int cpu) return 0; } +static int __cpuinit rcu_cpu_notify(struct notifier_block *self, + unsigned long action, void *hcpu) +{ + long cpu = (long)hcpu; + + switch (action) { + case CPU_UP_PREPARE: + case CPU_UP_PREPARE_FROZEN: + rcu_online_cpu_rt(cpu); + break; + case CPU_UP_CANCELED: + case CPU_UP_CANCELED_FROZEN: + case CPU_DEAD: + case CPU_DEAD_FROZEN: + rcu_offline_cpu_rt(cpu); + break; + default: + break; + } + return NOTIFY_OK; +} + +static struct notifier_block __cpuinitdata rcu_nb = { + .notifier_call = rcu_cpu_notify, +}; + void __init rcu_init_rt(void) { int cpu; @@ -972,6 +1008,22 @@ void __init rcu_init_rt(void) rdp->donetail = &rdp->donelist; } rcu_preempt_boost_init(); + register_cpu_notifier(&rcu_nb); + + /* + * We don't need protection against CPU-Hotplug here + * since + * a) If a CPU comes online while we are iterating over the + * cpu_online_map below, we would only end up making a + * duplicate call to rcu_online_cpu() which sets the corresponding + * CPU's mask in the rcu_cpu_online_map. + * + * b) A CPU cannot go offline at this point in time since the user + * does not have access to the sysfs interface, nor do we + * suspend the system. + */ + for_each_online_cpu(cpu) + rcu_cpu_notify(&rcu_nb, CPU_UP_PREPARE, (void *)(long) cpu); } /* -- -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/