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stop_machine(): stop_machine_run() changed to use cpu mask
Instead of a "cpu" arg with magic values NR_CPUS (any cpu) and ~0 (all cpus), pass a cpumask_t. Allow NULL for the common case (where we don't care which CPU the function is run on): temporary cpumask_t's are usually considered bad for stack space. This deprecates stop_machine_run, to be removed soon when all the callers are dead. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
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@ -5,19 +5,19 @@
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(and more). So the "read" side to such a lock is anything which
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diables preeempt. */
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#include <linux/cpu.h>
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#include <linux/cpumask.h>
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#include <asm/system.h>
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#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
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/* Deprecated, but useful for transition. */
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#define ALL_CPUS ~0U
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/**
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* stop_machine_run: freeze the machine on all CPUs and run this function
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* stop_machine: freeze the machine on all CPUs and run this function
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* @fn: the function to run
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* @data: the data ptr for the @fn()
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* @cpu: if @cpu == n, run @fn() on cpu n
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* if @cpu == NR_CPUS, run @fn() on any cpu
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* if @cpu == ALL_CPUS, run @fn() on every online CPU.
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* @cpus: the cpus to run the @fn() on (NULL = any online cpu)
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*
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* Description: This causes a thread to be scheduled on every cpu,
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* each of which disables interrupts. The result is that noone is
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@ -26,22 +26,22 @@
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*
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* This can be thought of as a very heavy write lock, equivalent to
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* grabbing every spinlock in the kernel. */
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int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
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int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
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/**
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* __stop_machine_run: freeze the machine on all CPUs and run this function
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* __stop_machine: freeze the machine on all CPUs and run this function
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* @fn: the function to run
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* @data: the data ptr for the @fn
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* @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
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* @cpus: the cpus to run the @fn() on (NULL = any online cpu)
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*
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* Description: This is a special version of the above, which assumes cpus
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* won't come or go while it's being called. Used by hotplug cpu.
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*/
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int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
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int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
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#else
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static inline int stop_machine_run(int (*fn)(void *), void *data,
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unsigned int cpu)
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static inline int stop_machine(int (*fn)(void *), void *data,
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const cpumask_t *cpus)
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{
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int ret;
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local_irq_disable();
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@ -50,4 +50,18 @@ static inline int stop_machine_run(int (*fn)(void *), void *data,
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return ret;
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}
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#endif /* CONFIG_SMP */
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static inline int __deprecated stop_machine_run(int (*fn)(void *), void *data,
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unsigned int cpu)
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{
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/* If they don't care which cpu fn runs on, just pick one. */
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if (cpu == NR_CPUS)
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return stop_machine(fn, data, NULL);
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else if (cpu == ~0U)
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return stop_machine(fn, data, &cpu_possible_map);
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else {
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cpumask_t cpus = cpumask_of_cpu(cpu);
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return stop_machine(fn, data, &cpus);
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}
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}
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#endif /* _LINUX_STOP_MACHINE */
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@ -248,8 +248,9 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
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cpus_setall(tmp);
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cpu_clear(cpu, tmp);
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set_cpus_allowed_ptr(current, &tmp);
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tmp = cpumask_of_cpu(cpu);
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err = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
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err = __stop_machine(take_cpu_down, &tcd_param, &tmp);
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if (err) {
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/* CPU didn't die: tell everyone. Can't complain. */
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if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
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@ -100,7 +100,7 @@ static int chill(void *unused)
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return 0;
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}
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int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
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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 i, err;
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struct stop_machine_data active, idle;
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@ -112,10 +112,6 @@ int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
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idle.fn = chill;
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idle.data = NULL;
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/* If they don't care which cpu fn runs on, just pick one. */
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if (cpu == NR_CPUS)
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cpu = any_online_cpu(cpu_online_map);
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/* This could be too big for stack on large machines. */
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threads = kcalloc(NR_CPUS, sizeof(threads[0]), GFP_KERNEL);
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if (!threads)
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@ -128,13 +124,16 @@ int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
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set_state(STOPMACHINE_PREPARE);
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for_each_online_cpu(i) {
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struct stop_machine_data *smdata;
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struct stop_machine_data *smdata = &idle;
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struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
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if (cpu == ALL_CPUS || i == cpu)
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smdata = &active;
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else
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smdata = &idle;
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if (!cpus) {
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if (i == first_cpu(cpu_online_map))
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smdata = &active;
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} else {
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if (cpu_isset(i, *cpus))
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smdata = &active;
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}
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threads[i] = kthread_create((void *)stop_cpu, smdata, "kstop%u",
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i);
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@ -154,7 +153,7 @@ int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
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/* We've created all the threads. Wake them all: hold this CPU so one
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* doesn't hit this CPU until we're ready. */
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cpu = get_cpu();
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get_cpu();
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for_each_online_cpu(i)
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wake_up_process(threads[i]);
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@ -177,15 +176,15 @@ kill_threads:
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return err;
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}
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int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
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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_run(fn, data, cpu);
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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_run);
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EXPORT_SYMBOL_GPL(stop_machine);
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