cpu_stop: add dummy implementation for UP

When !CONFIG_SMP, cpu_stop functions weren't defined at all which could lead to build failures if UP code uses cpu_stop facility. Add dummy cpu_stop implementation for UP. The waiting variants execute the work function directly with preempt disabled and stop_one_cpu_nowait() schedules a workqueue work. Makefile and ifdefs around stop_machine implementation are updated to accomodate CONFIG_SMP && !CONFIG_STOP_MACHINE case.

Tejun Heo committed 16 years ago

Commit bbf1bb31 parent fc390cd3 files · +68 −7Browse files

Unified · Split

3 files

include/linux/stop_machine.h +63 −6
kernel/Makefile +1 −1
kernel/stop_machine.c +4 −0

include/linux/stop_machine.h+63−6

@@ -6,8 +6,6 @@ · 5 unmodified lines
6	#include <linux/list.h>	6	#include <linux/list.h>
7	#include <asm/system.h>	7	#include <asm/system.h>
8		8
9	#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
10
11	/*	9	/*
12	* stop_cpu[s]() is simplistic per-cpu maximum priority cpu	10	* stop_cpu[s]() is simplistic per-cpu maximum priority cpu
13	* monopolization mechanism. The caller can specify a non-sleeping	11	* monopolization mechanism. The caller can specify a non-sleeping
@@ -18,9 +16,10 @@ · 4 unmodified lines
18	* up and requests are guaranteed to be served as long as the target	16	* up and requests are guaranteed to be served as long as the target
19	* cpus are online.	17	* cpus are online.
20	*/	18	*/
21
22	typedef int (cpu_stop_fn_t)(void arg);	19	typedef int (cpu_stop_fn_t)(void arg);
23		20
		21	#ifdef CONFIG_SMP
		22
24	struct cpu_stop_work {	23	struct cpu_stop_work {
25	struct list_head list; /* cpu_stopper->works */	24	struct list_head list; /* cpu_stopper->works */
26	cpu_stop_fn_t fn;	25	cpu_stop_fn_t fn;
@@ -34,12 +33,70 @@ void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, · 7 unmodified lines
34	int stop_cpus(const struct cpumask cpumask, cpu_stop_fn_t fn, void arg);	33	int stop_cpus(const struct cpumask cpumask, cpu_stop_fn_t fn, void arg);
35	int try_stop_cpus(const struct cpumask cpumask, cpu_stop_fn_t fn, void arg);	34	int try_stop_cpus(const struct cpumask cpumask, cpu_stop_fn_t fn, void arg);
36		35
		36	#else /* CONFIG_SMP */
		37
		38	#include <linux/workqueue.h>
		39
		40	struct cpu_stop_work {
		41	struct work_struct work;
		42	cpu_stop_fn_t fn;
		43	void *arg;
		44	};
		45
		46	static inline int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg)
		47	{
		48	int ret = -ENOENT;
		49	preempt_disable();
		50	if (cpu == smp_processor_id())
		51	ret = fn(arg);
		52	preempt_enable();
		53	return ret;
		54	}
		55
		56	static void stop_one_cpu_nowait_workfn(struct work_struct *work)
		57	{
		58	struct cpu_stop_work *stwork =
		59	container_of(work, struct cpu_stop_work, work);
		60	preempt_disable();
		61	stwork->fn(stwork->arg);
		62	preempt_enable();
		63	}
		64
		65	static inline void stop_one_cpu_nowait(unsigned int cpu,
		66	cpu_stop_fn_t fn, void *arg,
		67	struct cpu_stop_work *work_buf)
		68	{
		69	if (cpu == smp_processor_id()) {
		70	INIT_WORK(&work_buf->work, stop_one_cpu_nowait_workfn);
		71	work_buf->fn = fn;
		72	work_buf->arg = arg;
		73	schedule_work(&work_buf->work);
		74	}
		75	}
		76
		77	static inline int stop_cpus(const struct cpumask *cpumask,
		78	cpu_stop_fn_t fn, void *arg)
		79	{
		80	if (cpumask_test_cpu(raw_smp_processor_id(), cpumask))
		81	return stop_one_cpu(raw_smp_processor_id(), fn, arg);
		82	return -ENOENT;
		83	}
		84
		85	static inline int try_stop_cpus(const struct cpumask *cpumask,
		86	cpu_stop_fn_t fn, void *arg)
		87	{
		88	return stop_cpus(cpumask, fn, arg);
		89	}
		90
		91	#endif /* CONFIG_SMP */
		92
37	/*	93	/*
38	* stop_machine "Bogolock": stop the entire machine, disable	94	* stop_machine "Bogolock": stop the entire machine, disable
39	* interrupts. This is a very heavy lock, which is equivalent to	95	* interrupts. This is a very heavy lock, which is equivalent to
40	* grabbing every spinlock (and more). So the "read" side to such a	96	* grabbing every spinlock (and more). So the "read" side to such a
41	* lock is anything which disables preeempt.	97	* lock is anything which disables preeempt.
42	*/	98	*/
		99	#if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP)
43		100
44	/**	101	/**
45	* stop_machine: freeze the machine on all CPUs and run this function	102	* stop_machine: freeze the machine on all CPUs and run this function
@@ -67,7 +124,7 @@ int stop_machine(int (fn)(void ), void data, const struct cpumask cpus); · 21 unmodified lines
67	*/	124	*/
68	int __stop_machine(int (fn)(void ), void data, const struct cpumask cpus);	125	int __stop_machine(int (fn)(void ), void data, const struct cpumask cpus);
69		126
70	#else	127	#else /* CONFIG_STOP_MACHINE && CONFIG_SMP */
71		128
72	static inline int stop_machine(int (fn)(void ), void *data,	129	static inline int stop_machine(int (fn)(void ), void *data,
73	const struct cpumask *cpus)	130	const struct cpumask *cpus)
@@ -79,5 +136,5 @@ static inline int stop_machine(int (fn)(void ), void *data, · 5 unmodified lines
79	return ret;	136	return ret;
80	}	137	}
81		138
82	#endif /* CONFIG_SMP */	139	#endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */
83	#endif /* _LINUX_STOP_MACHINE */	140	#endif /* _LINUX_STOP_MACHINE */

kernel/Makefile+1−1

@@ -68,7 +68,7 @@ obj-$(CONFIG_USER_NS) += user_namespace.o · 67 unmodified lines
68	obj-$(CONFIG_PID_NS) += pid_namespace.o	68	obj-$(CONFIG_PID_NS) += pid_namespace.o
69	obj-$(CONFIG_IKCONFIG) += configs.o	69	obj-$(CONFIG_IKCONFIG) += configs.o
70	obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o	70	obj-$(CONFIG_RESOURCE_COUNTERS) += res_counter.o
71	obj-$(CONFIG_STOP_MACHINE) += stop_machine.o	71	obj-$(CONFIG_SMP) += stop_machine.o
72	obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o	72	obj-$(CONFIG_KPROBES_SANITY_TEST) += test_kprobes.o
73	obj-$(CONFIG_AUDIT) += audit.o auditfilter.o audit_watch.o	73	obj-$(CONFIG_AUDIT) += audit.o auditfilter.o audit_watch.o
74	obj-$(CONFIG_AUDITSYSCALL) += auditsc.o	74	obj-$(CONFIG_AUDITSYSCALL) += auditsc.o

kernel/stop_machine.c+4−0

 }
 early_initcall(cpu_stop_init);
+#ifdef CONFIG_STOP_MACHINE
 /* This controls the threads on each CPU. */
 enum stopmachine_state {
 	/* Dummy starting state for thread. */
 	return ret;
 }
 EXPORT_SYMBOL_GPL(stop_machine);
+#endif	/* CONFIG_STOP_MACHINE */

cpu_stop: add dummy implementation for UP

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