diff options
Diffstat (limited to 'kernel/smpboot.c')
-rw-r--r-- | kernel/smpboot.c | 163 |
1 files changed, 0 insertions, 163 deletions
diff --git a/kernel/smpboot.c b/kernel/smpboot.c index 2c7396da470c..f47d8f375946 100644 --- a/kernel/smpboot.c +++ b/kernel/smpboot.c @@ -325,166 +325,3 @@ void smpboot_unregister_percpu_thread(struct smp_hotplug_thread *plug_thread) cpus_read_unlock(); } EXPORT_SYMBOL_GPL(smpboot_unregister_percpu_thread); - -static DEFINE_PER_CPU(atomic_t, cpu_hotplug_state) = ATOMIC_INIT(CPU_POST_DEAD); - -/* - * Called to poll specified CPU's state, for example, when waiting for - * a CPU to come online. - */ -int cpu_report_state(int cpu) -{ - return atomic_read(&per_cpu(cpu_hotplug_state, cpu)); -} - -/* - * If CPU has died properly, set its state to CPU_UP_PREPARE and - * return success. Otherwise, return -EBUSY if the CPU died after - * cpu_wait_death() timed out. And yet otherwise again, return -EAGAIN - * if cpu_wait_death() timed out and the CPU still hasn't gotten around - * to dying. In the latter two cases, the CPU might not be set up - * properly, but it is up to the arch-specific code to decide. - * Finally, -EIO indicates an unanticipated problem. - * - * Note that it is permissible to omit this call entirely, as is - * done in architectures that do no CPU-hotplug error checking. - */ -int cpu_check_up_prepare(int cpu) -{ - if (!IS_ENABLED(CONFIG_HOTPLUG_CPU)) { - atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_UP_PREPARE); - return 0; - } - - switch (atomic_read(&per_cpu(cpu_hotplug_state, cpu))) { - - case CPU_POST_DEAD: - - /* The CPU died properly, so just start it up again. */ - atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_UP_PREPARE); - return 0; - - case CPU_DEAD_FROZEN: - - /* - * Timeout during CPU death, so let caller know. - * The outgoing CPU completed its processing, but after - * cpu_wait_death() timed out and reported the error. The - * caller is free to proceed, in which case the state - * will be reset properly by cpu_set_state_online(). - * Proceeding despite this -EBUSY return makes sense - * for systems where the outgoing CPUs take themselves - * offline, with no post-death manipulation required from - * a surviving CPU. - */ - return -EBUSY; - - case CPU_BROKEN: - - /* - * The most likely reason we got here is that there was - * a timeout during CPU death, and the outgoing CPU never - * did complete its processing. This could happen on - * a virtualized system if the outgoing VCPU gets preempted - * for more than five seconds, and the user attempts to - * immediately online that same CPU. Trying again later - * might return -EBUSY above, hence -EAGAIN. - */ - return -EAGAIN; - - case CPU_UP_PREPARE: - /* - * Timeout while waiting for the CPU to show up. Allow to try - * again later. - */ - return 0; - - default: - - /* Should not happen. Famous last words. */ - return -EIO; - } -} - -/* - * Mark the specified CPU online. - * - * Note that it is permissible to omit this call entirely, as is - * done in architectures that do no CPU-hotplug error checking. - */ -void cpu_set_state_online(int cpu) -{ - (void)atomic_xchg(&per_cpu(cpu_hotplug_state, cpu), CPU_ONLINE); -} - -#ifdef CONFIG_HOTPLUG_CPU - -/* - * Wait for the specified CPU to exit the idle loop and die. - */ -bool cpu_wait_death(unsigned int cpu, int seconds) -{ - int jf_left = seconds * HZ; - int oldstate; - bool ret = true; - int sleep_jf = 1; - - might_sleep(); - - /* The outgoing CPU will normally get done quite quickly. */ - if (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) == CPU_DEAD) - goto update_state_early; - udelay(5); - - /* But if the outgoing CPU dawdles, wait increasingly long times. */ - while (atomic_read(&per_cpu(cpu_hotplug_state, cpu)) != CPU_DEAD) { - schedule_timeout_uninterruptible(sleep_jf); - jf_left -= sleep_jf; - if (jf_left <= 0) - break; - sleep_jf = DIV_ROUND_UP(sleep_jf * 11, 10); - } -update_state_early: - oldstate = atomic_read(&per_cpu(cpu_hotplug_state, cpu)); -update_state: - if (oldstate == CPU_DEAD) { - /* Outgoing CPU died normally, update state. */ - smp_mb(); /* atomic_read() before update. */ - atomic_set(&per_cpu(cpu_hotplug_state, cpu), CPU_POST_DEAD); - } else { - /* Outgoing CPU still hasn't died, set state accordingly. */ - if (!atomic_try_cmpxchg(&per_cpu(cpu_hotplug_state, cpu), - &oldstate, CPU_BROKEN)) - goto update_state; - ret = false; - } - return ret; -} - -/* - * Called by the outgoing CPU to report its successful death. Return - * false if this report follows the surviving CPU's timing out. - * - * A separate "CPU_DEAD_FROZEN" is used when the surviving CPU - * timed out. This approach allows architectures to omit calls to - * cpu_check_up_prepare() and cpu_set_state_online() without defeating - * the next cpu_wait_death()'s polling loop. - */ -bool cpu_report_death(void) -{ - int oldstate; - int newstate; - int cpu = smp_processor_id(); - - oldstate = atomic_read(&per_cpu(cpu_hotplug_state, cpu)); - do { - if (oldstate != CPU_BROKEN) - newstate = CPU_DEAD; - else - newstate = CPU_DEAD_FROZEN; - } while (!atomic_try_cmpxchg(&per_cpu(cpu_hotplug_state, cpu), - &oldstate, newstate)); - return newstate == CPU_DEAD; -} - -#endif /* #ifdef CONFIG_HOTPLUG_CPU */ |