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authorRusty Russell <rusty@rustcorp.com.au>2008-07-28 12:16:30 -0500
committerRusty Russell <rusty@rustcorp.com.au>2008-07-28 12:16:30 +1000
commiteeec4fad963490821348a331cca6102ae1c4a7a3 (patch)
tree163a7d9414d719fccac096d1ba822416f705b397
parent04321587584272f4e8b9818f319f40caf8eeee13 (diff)
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>
-rw-r--r--include/linux/stop_machine.h34
-rw-r--r--kernel/cpu.c3
-rw-r--r--kernel/stop_machine.c27
3 files changed, 39 insertions, 25 deletions
diff --git a/include/linux/stop_machine.h b/include/linux/stop_machine.h
index 36c2c7284eb3..f1cb0ba6d715 100644
--- a/include/linux/stop_machine.h
+++ b/include/linux/stop_machine.h
@@ -5,19 +5,19 @@
(and more). So the "read" side to such a lock is anything which
diables preeempt. */
#include <linux/cpu.h>
+#include <linux/cpumask.h>
#include <asm/system.h>
#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
+/* Deprecated, but useful for transition. */
#define ALL_CPUS ~0U
/**
- * stop_machine_run: freeze the machine on all CPUs and run this function
+ * stop_machine: freeze the machine on all CPUs and run this function
* @fn: the function to run
* @data: the data ptr for the @fn()
- * @cpu: if @cpu == n, run @fn() on cpu n
- * if @cpu == NR_CPUS, run @fn() on any cpu
- * if @cpu == ALL_CPUS, run @fn() on every online CPU.
+ * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
*
* Description: This causes a thread to be scheduled on every cpu,
* each of which disables interrupts. The result is that noone is
@@ -26,22 +26,22 @@
*
* This can be thought of as a very heavy write lock, equivalent to
* grabbing every spinlock in the kernel. */
-int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
+int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
/**
- * __stop_machine_run: freeze the machine on all CPUs and run this function
+ * __stop_machine: freeze the machine on all CPUs and run this function
* @fn: the function to run
* @data: the data ptr for the @fn
- * @cpu: the cpu to run @fn on (or any, if @cpu == NR_CPUS.
+ * @cpus: the cpus to run the @fn() on (NULL = any online cpu)
*
* Description: This is a special version of the above, which assumes cpus
* won't come or go while it's being called. Used by hotplug cpu.
*/
-int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu);
+int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus);
#else
-static inline int stop_machine_run(int (*fn)(void *), void *data,
- unsigned int cpu)
+static inline int stop_machine(int (*fn)(void *), void *data,
+ const cpumask_t *cpus)
{
int ret;
local_irq_disable();
@@ -50,4 +50,18 @@ static inline int stop_machine_run(int (*fn)(void *), void *data,
return ret;
}
#endif /* CONFIG_SMP */
+
+static inline int __deprecated stop_machine_run(int (*fn)(void *), void *data,
+ unsigned int cpu)
+{
+ /* If they don't care which cpu fn runs on, just pick one. */
+ if (cpu == NR_CPUS)
+ return stop_machine(fn, data, NULL);
+ else if (cpu == ~0U)
+ return stop_machine(fn, data, &cpu_possible_map);
+ else {
+ cpumask_t cpus = cpumask_of_cpu(cpu);
+ return stop_machine(fn, data, &cpus);
+ }
+}
#endif /* _LINUX_STOP_MACHINE */
diff --git a/kernel/cpu.c b/kernel/cpu.c
index 53cf508f975a..29510d68338a 100644
--- a/kernel/cpu.c
+++ b/kernel/cpu.c
@@ -248,8 +248,9 @@ static int __ref _cpu_down(unsigned int cpu, int tasks_frozen)
cpus_setall(tmp);
cpu_clear(cpu, tmp);
set_cpus_allowed_ptr(current, &tmp);
+ tmp = cpumask_of_cpu(cpu);
- err = __stop_machine_run(take_cpu_down, &tcd_param, cpu);
+ err = __stop_machine(take_cpu_down, &tcd_param, &tmp);
if (err) {
/* CPU didn't die: tell everyone. Can't complain. */
if (raw_notifier_call_chain(&cpu_chain, CPU_DOWN_FAILED | mod,
diff --git a/kernel/stop_machine.c b/kernel/stop_machine.c
index 35882dccc943..e446c7c7d6a9 100644
--- a/kernel/stop_machine.c
+++ b/kernel/stop_machine.c
@@ -100,7 +100,7 @@ static int chill(void *unused)
return 0;
}
-int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
+int __stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)
{
int i, err;
struct stop_machine_data active, idle;
@@ -112,10 +112,6 @@ int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
idle.fn = chill;
idle.data = NULL;
- /* If they don't care which cpu fn runs on, just pick one. */
- if (cpu == NR_CPUS)
- cpu = any_online_cpu(cpu_online_map);
-
/* This could be too big for stack on large machines. */
threads = kcalloc(NR_CPUS, sizeof(threads[0]), GFP_KERNEL);
if (!threads)
@@ -128,13 +124,16 @@ int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
set_state(STOPMACHINE_PREPARE);
for_each_online_cpu(i) {
- struct stop_machine_data *smdata;
+ struct stop_machine_data *smdata = &idle;
struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
- if (cpu == ALL_CPUS || i == cpu)
- smdata = &active;
- else
- smdata = &idle;
+ if (!cpus) {
+ if (i == first_cpu(cpu_online_map))
+ smdata = &active;
+ } else {
+ if (cpu_isset(i, *cpus))
+ smdata = &active;
+ }
threads[i] = kthread_create((void *)stop_cpu, smdata, "kstop%u",
i);
@@ -154,7 +153,7 @@ int __stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
/* We've created all the threads. Wake them all: hold this CPU so one
* doesn't hit this CPU until we're ready. */
- cpu = get_cpu();
+ get_cpu();
for_each_online_cpu(i)
wake_up_process(threads[i]);
@@ -177,15 +176,15 @@ kill_threads:
return err;
}
-int stop_machine_run(int (*fn)(void *), void *data, unsigned int cpu)
+int stop_machine(int (*fn)(void *), void *data, const cpumask_t *cpus)
{
int ret;
/* No CPUs can come up or down during this. */
get_online_cpus();
- ret = __stop_machine_run(fn, data, cpu);
+ ret = __stop_machine(fn, data, cpus);
put_online_cpus();
return ret;
}
-EXPORT_SYMBOL_GPL(stop_machine_run);
+EXPORT_SYMBOL_GPL(stop_machine);