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![Rusty Russell](/assets/img/avatar_default.png)
Bug #11989: Suspend failure on NForce4-based boards due to chanes in stop_machine We should not access active.fnret outside the lock; in theory the next stop_machine could overwrite it. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Tested-by: "Rafael J. Wysocki" <rjw@sisk.pl> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
164 lines
3.8 KiB
C
164 lines
3.8 KiB
C
/* Copyright 2008, 2005 Rusty Russell rusty@rustcorp.com.au IBM Corporation.
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* GPL v2 and any later version.
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*/
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#include <linux/cpu.h>
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#include <linux/err.h>
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#include <linux/kthread.h>
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#include <linux/module.h>
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#include <linux/sched.h>
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#include <linux/stop_machine.h>
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#include <linux/syscalls.h>
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#include <linux/interrupt.h>
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#include <asm/atomic.h>
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#include <asm/uaccess.h>
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/* This controls the threads on each CPU. */
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enum stopmachine_state {
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/* Dummy starting state for thread. */
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STOPMACHINE_NONE,
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/* Awaiting everyone to be scheduled. */
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STOPMACHINE_PREPARE,
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/* Disable interrupts. */
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STOPMACHINE_DISABLE_IRQ,
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/* Run the function */
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STOPMACHINE_RUN,
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/* Exit */
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STOPMACHINE_EXIT,
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};
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static enum stopmachine_state state;
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struct stop_machine_data {
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int (*fn)(void *);
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void *data;
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int fnret;
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};
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/* Like num_online_cpus(), but hotplug cpu uses us, so we need this. */
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static unsigned int num_threads;
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static atomic_t thread_ack;
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static DEFINE_MUTEX(lock);
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static struct workqueue_struct *stop_machine_wq;
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static struct stop_machine_data active, idle;
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static const cpumask_t *active_cpus;
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static void *stop_machine_work;
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static void set_state(enum stopmachine_state newstate)
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{
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/* Reset ack counter. */
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atomic_set(&thread_ack, num_threads);
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smp_wmb();
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state = newstate;
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}
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/* Last one to ack a state moves to the next state. */
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static void ack_state(void)
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{
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if (atomic_dec_and_test(&thread_ack))
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set_state(state + 1);
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}
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/* This is the actual function which stops the CPU. It runs
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* in the context of a dedicated stopmachine workqueue. */
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static void stop_cpu(struct work_struct *unused)
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{
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enum stopmachine_state curstate = STOPMACHINE_NONE;
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struct stop_machine_data *smdata = &idle;
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int cpu = smp_processor_id();
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int err;
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if (!active_cpus) {
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if (cpu == first_cpu(cpu_online_map))
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smdata = &active;
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} else {
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if (cpu_isset(cpu, *active_cpus))
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smdata = &active;
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}
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/* Simple state machine */
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do {
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/* Chill out and ensure we re-read stopmachine_state. */
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cpu_relax();
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if (state != curstate) {
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curstate = state;
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switch (curstate) {
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case STOPMACHINE_DISABLE_IRQ:
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local_irq_disable();
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hard_irq_disable();
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break;
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case STOPMACHINE_RUN:
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/* On multiple CPUs only a single error code
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* is needed to tell that something failed. */
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err = smdata->fn(smdata->data);
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if (err)
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smdata->fnret = err;
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break;
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default:
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break;
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}
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ack_state();
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}
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} while (curstate != STOPMACHINE_EXIT);
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local_irq_enable();
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}
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/* Callback for CPUs which aren't supposed to do anything. */
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static int chill(void *unused)
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{
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return 0;
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}
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int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)
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{
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struct work_struct *sm_work;
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int i, ret;
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/* Set up initial state. */
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mutex_lock(&lock);
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num_threads = num_online_cpus();
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active_cpus = cpus;
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active.fn = fn;
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active.data = data;
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active.fnret = 0;
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idle.fn = chill;
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idle.data = NULL;
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set_state(STOPMACHINE_PREPARE);
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/* Schedule the stop_cpu work on all cpus: hold this CPU so one
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* doesn't hit this CPU until we're ready. */
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get_cpu();
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for_each_online_cpu(i) {
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sm_work = percpu_ptr(stop_machine_work, i);
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INIT_WORK(sm_work, stop_cpu);
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queue_work_on(i, stop_machine_wq, sm_work);
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}
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/* This will release the thread on our CPU. */
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put_cpu();
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flush_workqueue(stop_machine_wq);
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ret = active.fnret;
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mutex_unlock(&lock);
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return ret;
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}
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int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)
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{
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int ret;
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/* No CPUs can come up or down during this. */
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get_online_cpus();
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ret = __stop_machine(fn, data, cpus);
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put_online_cpus();
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return ret;
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}
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EXPORT_SYMBOL_GPL(stop_machine);
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static int __init stop_machine_init(void)
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{
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stop_machine_wq = create_rt_workqueue("kstop");
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stop_machine_work = alloc_percpu(struct work_struct);
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return 0;
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}
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core_initcall(stop_machine_init);
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