Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | #ifndef _LINUX_STOP_MACHINE |
| 2 | #define _LINUX_STOP_MACHINE |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 3 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 4 | #include <linux/cpu.h> |
Rusty Russell | eeec4fa | 2008-07-28 12:16:30 -0500 | [diff] [blame] | 5 | #include <linux/cpumask.h> |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 6 | #include <linux/list.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 7 | #include <asm/system.h> |
| 8 | |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 9 | /* |
| 10 | * stop_cpu[s]() is simplistic per-cpu maximum priority cpu |
| 11 | * monopolization mechanism. The caller can specify a non-sleeping |
| 12 | * function to be executed on a single or multiple cpus preempting all |
| 13 | * other processes and monopolizing those cpus until it finishes. |
| 14 | * |
| 15 | * Resources for this mechanism are preallocated when a cpu is brought |
| 16 | * up and requests are guaranteed to be served as long as the target |
| 17 | * cpus are online. |
| 18 | */ |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 19 | typedef int (*cpu_stop_fn_t)(void *arg); |
| 20 | |
Tejun Heo | bbf1bb3 | 2010-05-08 16:20:53 +0200 | [diff] [blame] | 21 | #ifdef CONFIG_SMP |
| 22 | |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 23 | struct cpu_stop_work { |
| 24 | struct list_head list; /* cpu_stopper->works */ |
| 25 | cpu_stop_fn_t fn; |
| 26 | void *arg; |
| 27 | struct cpu_stop_done *done; |
| 28 | }; |
| 29 | |
| 30 | int stop_one_cpu(unsigned int cpu, cpu_stop_fn_t fn, void *arg); |
| 31 | void stop_one_cpu_nowait(unsigned int cpu, cpu_stop_fn_t fn, void *arg, |
| 32 | struct cpu_stop_work *work_buf); |
| 33 | int 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); |
| 35 | |
Tejun Heo | bbf1bb3 | 2010-05-08 16:20:53 +0200 | [diff] [blame] | 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 | |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 93 | /* |
| 94 | * stop_machine "Bogolock": stop the entire machine, disable |
| 95 | * interrupts. This is a very heavy lock, which is equivalent to |
| 96 | * grabbing every spinlock (and more). So the "read" side to such a |
Jonathan Neuschäfer | 1816315 | 2011-06-19 11:50:22 +0200 | [diff] [blame] | 97 | * lock is anything which disables preemption. |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 98 | */ |
Tejun Heo | bbf1bb3 | 2010-05-08 16:20:53 +0200 | [diff] [blame] | 99 | #if defined(CONFIG_STOP_MACHINE) && defined(CONFIG_SMP) |
Tejun Heo | 1142d81 | 2010-05-06 18:49:20 +0200 | [diff] [blame] | 100 | |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 101 | /** |
Rusty Russell | eeec4fa | 2008-07-28 12:16:30 -0500 | [diff] [blame] | 102 | * stop_machine: freeze the machine on all CPUs and run this function |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 103 | * @fn: the function to run |
| 104 | * @data: the data ptr for the @fn() |
Rusty Russell | eeec4fa | 2008-07-28 12:16:30 -0500 | [diff] [blame] | 105 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 106 | * |
Rusty Russell | ffdb597 | 2008-07-28 12:16:28 -0500 | [diff] [blame] | 107 | * Description: This causes a thread to be scheduled on every cpu, |
Lucas De Marchi | 25985ed | 2011-03-30 22:57:33 -0300 | [diff] [blame] | 108 | * each of which disables interrupts. The result is that no one is |
Rusty Russell | ffdb597 | 2008-07-28 12:16:28 -0500 | [diff] [blame] | 109 | * holding a spinlock or inside any other preempt-disabled region when |
| 110 | * @fn() runs. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 111 | * |
| 112 | * This can be thought of as a very heavy write lock, equivalent to |
| 113 | * grabbing every spinlock in the kernel. */ |
Rusty Russell | 41c7bb9 | 2009-01-01 10:12:28 +1030 | [diff] [blame] | 114 | int stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 115 | |
| 116 | /** |
Rusty Russell | eeec4fa | 2008-07-28 12:16:30 -0500 | [diff] [blame] | 117 | * __stop_machine: freeze the machine on all CPUs and run this function |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 118 | * @fn: the function to run |
| 119 | * @data: the data ptr for the @fn |
Rusty Russell | eeec4fa | 2008-07-28 12:16:30 -0500 | [diff] [blame] | 120 | * @cpus: the cpus to run the @fn() on (NULL = any online cpu) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 121 | * |
Rusty Russell | ffdb597 | 2008-07-28 12:16:28 -0500 | [diff] [blame] | 122 | * Description: This is a special version of the above, which assumes cpus |
| 123 | * won't come or go while it's being called. Used by hotplug cpu. |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 124 | */ |
Rusty Russell | 41c7bb9 | 2009-01-01 10:12:28 +1030 | [diff] [blame] | 125 | int __stop_machine(int (*fn)(void *), void *data, const struct cpumask *cpus); |
Heiko Carstens | 9ea09af | 2008-12-22 12:36:30 +0100 | [diff] [blame] | 126 | |
Tejun Heo | f740e6cd | 2011-06-23 11:19:28 -0700 | [diff] [blame] | 127 | int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, |
| 128 | const struct cpumask *cpus); |
| 129 | |
Tejun Heo | bbf1bb3 | 2010-05-08 16:20:53 +0200 | [diff] [blame] | 130 | #else /* CONFIG_STOP_MACHINE && CONFIG_SMP */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 131 | |
Masami Hiramatsu | 087a4eb | 2010-10-14 12:10:30 +0900 | [diff] [blame] | 132 | static inline int __stop_machine(int (*fn)(void *), void *data, |
| 133 | const struct cpumask *cpus) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 134 | { |
Tejun Heo | f740e6cd | 2011-06-23 11:19:28 -0700 | [diff] [blame] | 135 | unsigned long flags; |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 136 | int ret; |
Tejun Heo | f740e6cd | 2011-06-23 11:19:28 -0700 | [diff] [blame] | 137 | local_irq_save(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 138 | ret = fn(data); |
Tejun Heo | f740e6cd | 2011-06-23 11:19:28 -0700 | [diff] [blame] | 139 | local_irq_restore(flags); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 140 | return ret; |
| 141 | } |
Heiko Carstens | 9ea09af | 2008-12-22 12:36:30 +0100 | [diff] [blame] | 142 | |
Masami Hiramatsu | 087a4eb | 2010-10-14 12:10:30 +0900 | [diff] [blame] | 143 | static inline int stop_machine(int (*fn)(void *), void *data, |
| 144 | const struct cpumask *cpus) |
| 145 | { |
| 146 | return __stop_machine(fn, data, cpus); |
| 147 | } |
| 148 | |
Tejun Heo | f740e6cd | 2011-06-23 11:19:28 -0700 | [diff] [blame] | 149 | static inline int stop_machine_from_inactive_cpu(int (*fn)(void *), void *data, |
| 150 | const struct cpumask *cpus) |
| 151 | { |
| 152 | return __stop_machine(fn, data, cpus); |
| 153 | } |
| 154 | |
Tejun Heo | bbf1bb3 | 2010-05-08 16:20:53 +0200 | [diff] [blame] | 155 | #endif /* CONFIG_STOP_MACHINE && CONFIG_SMP */ |
| 156 | #endif /* _LINUX_STOP_MACHINE */ |