diff options
| -rw-r--r-- | include/linux/smp.h | 24 | ||||
| -rw-r--r-- | kernel/smp.c | 61 |
2 files changed, 85 insertions, 0 deletions
diff --git a/include/linux/smp.h b/include/linux/smp.h index d0adb7898d54..10530d92c04b 100644 --- a/include/linux/smp.h +++ b/include/linux/smp.h @@ -109,6 +109,15 @@ void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, void *info, bool wait); /* + * Call a function on each processor for which the supplied function + * cond_func returns a positive value. This may include the local + * processor. + */ +void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), + smp_call_func_t func, void *info, bool wait, + gfp_t gfp_flags); + +/* * Mark the boot cpu "online" so that it can call console drivers in * printk() and can access its per-cpu storage. */ @@ -153,6 +162,21 @@ static inline int up_smp_call_function(smp_call_func_t func, void *info) local_irq_enable(); \ } \ } while (0) +/* + * Preemption is disabled here to make sure the cond_func is called under the + * same condtions in UP and SMP. + */ +#define on_each_cpu_cond(cond_func, func, info, wait, gfp_flags)\ + do { \ + void *__info = (info); \ + preempt_disable(); \ + if ((cond_func)(0, __info)) { \ + local_irq_disable(); \ + (func)(__info); \ + local_irq_enable(); \ + } \ + preempt_enable(); \ + } while (0) static inline void smp_send_reschedule(int cpu) { } #define num_booting_cpus() 1 diff --git a/kernel/smp.c b/kernel/smp.c index a081e6ce0e0a..2f8b10ecf759 100644 --- a/kernel/smp.c +++ b/kernel/smp.c @@ -730,3 +730,64 @@ void on_each_cpu_mask(const struct cpumask *mask, smp_call_func_t func, put_cpu(); } EXPORT_SYMBOL(on_each_cpu_mask); + +/* + * on_each_cpu_cond(): Call a function on each processor for which + * the supplied function cond_func returns true, optionally waiting + * for all the required CPUs to finish. This may include the local + * processor. + * @cond_func: A callback function that is passed a cpu id and + * the the info parameter. The function is called + * with preemption disabled. The function should + * return a blooean value indicating whether to IPI + * the specified CPU. + * @func: The function to run on all applicable CPUs. + * This must be fast and non-blocking. + * @info: An arbitrary pointer to pass to both functions. + * @wait: If true, wait (atomically) until function has + * completed on other CPUs. + * @gfp_flags: GFP flags to use when allocating the cpumask + * used internally by the function. + * + * The function might sleep if the GFP flags indicates a non + * atomic allocation is allowed. + * + * Preemption is disabled to protect against CPUs going offline but not online. + * CPUs going online during the call will not be seen or sent an IPI. + * + * You must not call this function with disabled interrupts or + * from a hardware interrupt handler or from a bottom half handler. + */ +void on_each_cpu_cond(bool (*cond_func)(int cpu, void *info), + smp_call_func_t func, void *info, bool wait, + gfp_t gfp_flags) +{ + cpumask_var_t cpus; + int cpu, ret; + + might_sleep_if(gfp_flags & __GFP_WAIT); + + if (likely(zalloc_cpumask_var(&cpus, (gfp_flags|__GFP_NOWARN)))) { + preempt_disable(); + for_each_online_cpu(cpu) + if (cond_func(cpu, info)) + cpumask_set_cpu(cpu, cpus); + on_each_cpu_mask(cpus, func, info, wait); + preempt_enable(); + free_cpumask_var(cpus); + } else { + /* + * No free cpumask, bother. No matter, we'll + * just have to IPI them one by one. + */ + preempt_disable(); + for_each_online_cpu(cpu) + if (cond_func(cpu, info)) { + ret = smp_call_function_single(cpu, func, + info, wait); + WARN_ON_ONCE(!ret); + } + preempt_enable(); + } +} +EXPORT_SYMBOL(on_each_cpu_cond); |