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authorBjoern B. Brandenburg <bbb@cs.unc.edu>2007-05-14 10:01:10 -0400
committerBjoern B. Brandenburg <bbb@cs.unc.edu>2007-05-14 10:01:10 -0400
commit49b22590d881d19a7fed73401de148122431671e (patch)
tree53898ca69005e1d1f3f147c68bc8b3e4ebd94a02 /arch/i386
parentf5c781fccc56aae85f4232df5ee16cd3b27f8ccd (diff)
Start of LITMUS semaphore, PI, and SRP rewrite.
Rearrange the code to get out of the architecture dependent areas of the kernel and make it live in a central file, kernel/litmus_sem.c.
Diffstat (limited to 'arch/i386')
-rw-r--r--arch/i386/kernel/Makefile3
-rw-r--r--arch/i386/kernel/pi_sem_syscalls.c132
-rw-r--r--arch/i386/kernel/sem_syscalls.c92
-rw-r--r--arch/i386/kernel/srp_sem_syscalls.c250
4 files changed, 1 insertions, 476 deletions
diff --git a/arch/i386/kernel/Makefile b/arch/i386/kernel/Makefile
index f77d3e4bc7..1e8988e558 100644
--- a/arch/i386/kernel/Makefile
+++ b/arch/i386/kernel/Makefile
@@ -7,8 +7,7 @@ extra-y := head.o init_task.o vmlinux.lds
7obj-y := process.o signal.o entry.o traps.o irq.o \ 7obj-y := process.o signal.o entry.o traps.o irq.o \
8 ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_i386.o \ 8 ptrace.o time.o ioport.o ldt.o setup.o i8259.o sys_i386.o \
9 pci-dma.o i386_ksyms.o i387.o bootflag.o e820.o\ 9 pci-dma.o i386_ksyms.o i387.o bootflag.o e820.o\
10 quirks.o i8237.o topology.o alternative.o i8253.o tsc.o \ 10 quirks.o i8237.o topology.o alternative.o i8253.o tsc.o
11 pi_sem_syscalls.o sem_syscalls.o srp_sem_syscalls.o
12 11
13obj-$(CONFIG_STACKTRACE) += stacktrace.o 12obj-$(CONFIG_STACKTRACE) += stacktrace.o
14obj-y += cpu/ 13obj-y += cpu/
diff --git a/arch/i386/kernel/pi_sem_syscalls.c b/arch/i386/kernel/pi_sem_syscalls.c
deleted file mode 100644
index 66f79aa88a..0000000000
--- a/arch/i386/kernel/pi_sem_syscalls.c
+++ /dev/null
@@ -1,132 +0,0 @@
1#ifdef __KERNEL__
2
3/*
4 * SMP- and interrupt-safe semaphores, with priority inheritance.
5 * Much of the code here is borrowed from include/asm-i386/semaphore.h.
6 */
7
8#include <asm/atomic.h>
9#include <linux/sched.h>
10#include <linux/wait.h>
11#include <linux/sched_plugin.h>
12
13#define MAX_PI_SEMAPHORES 256
14
15struct pi_semaphore pi_sems[MAX_PI_SEMAPHORES]; /* all PI sems */
16typedef int pi_sema_id; /* Userspace ID of a pi_semaphore */
17
18/* Initialize PI semaphores at boot time. */
19static int __init pi_sema_boot_init(void)
20{
21 pi_sema_id sem_id;
22
23 printk("Initializing PI semaphores...");
24 for (sem_id = 0; sem_id < MAX_PI_SEMAPHORES; sem_id++)
25 pi_sems[sem_id].used = 0;
26 printk(" done!\n");
27
28 return 0;
29}
30__initcall(pi_sema_boot_init);
31
32/* Find a free semaphore and return. */
33asmlinkage long sys_pi_sema_init (void)
34{
35 pi_sema_id sem_id;
36
37 for (sem_id = 0; sem_id < MAX_PI_SEMAPHORES; sem_id++) {
38 if (!cmpxchg(&pi_sems[sem_id].used, 0, 1)) {
39 atomic_set(&pi_sems[sem_id].count, 1);
40 pi_sems[sem_id].sleepers = 0;
41 init_waitqueue_head(&pi_sems[sem_id].wait);
42 pi_sems[sem_id].hp_sem_task = NULL;
43 pi_sems[sem_id].holder = NULL;
44 return sem_id;
45 }
46 }
47 return -ENOMEM;
48}
49
50/*
51 * This is ugly, but we want the default case to fall through.
52 * "__down_failed" is a special asm handler that calls the C
53 * routine that actually waits. See arch/i386/kernel/semaphore.c
54 */
55void __sys_pi_down(struct pi_semaphore * sem)
56{
57 might_sleep();
58 /* Checking for active waitqueue gives others a chance... */
59 if (atomic_dec_return(&sem->count) < 0 || waitqueue_active(&sem->wait))
60 __pi_down(sem);
61}
62
63asmlinkage long sys_pi_down(pi_sema_id sem_id)
64{
65 unsigned long flags;
66
67 if (sem_id < 0 || sem_id >= MAX_PI_SEMAPHORES)
68 return -EINVAL;
69
70 __sys_pi_down(&pi_sems[sem_id]);
71
72 /* Update inherited priority if required. */
73 spin_lock_irqsave(&pi_sems[sem_id].wait.lock, flags);
74 if (!pi_sems[sem_id].holder) {
75 pi_sems[sem_id].holder = current;
76 curr_sched_plugin->inherit_priority(&pi_sems[sem_id], NULL);
77 }
78 spin_unlock_irqrestore(&pi_sems[sem_id].wait.lock, flags);
79 return 0;
80}
81
82/*
83 * We always jump to wake people and update semaphore priority.
84 * If the wait queue is empty, semaphore and priority update will
85 * still operate correctly.
86 */
87void __sys_pi_up(struct pi_semaphore * sem)
88{
89 atomic_inc(&sem->count);
90 __pi_up(sem);
91}
92
93asmlinkage long sys_pi_up(pi_sema_id sem_id)
94{
95 if (sem_id < 0 || sem_id >= MAX_PI_SEMAPHORES)
96 return -EINVAL;
97
98 __sys_pi_up(&pi_sems[sem_id]);
99 return 0;
100}
101
102/* Clear wait queue and wakeup waiting tasks, and free semaphore. */
103asmlinkage long sys_pi_sema_free(pi_sema_id sem_id)
104{
105 struct list_head *tmp, *next;
106 unsigned long flags;
107
108 if (sem_id < 0 || sem_id >= MAX_PI_SEMAPHORES)
109 return -EINVAL;
110
111 spin_lock_irqsave(&pi_sems[sem_id].wait.lock, flags);
112 if (waitqueue_active(&pi_sems[sem_id].wait)) {
113 list_for_each_safe(tmp, next,
114 &pi_sems[sem_id].wait.task_list) {
115 wait_queue_t *curr = list_entry(tmp, wait_queue_t,
116 task_list);
117 list_del(tmp);
118 set_rt_flags((struct task_struct*)curr->private,
119 RT_F_EXIT_SEM);
120 curr->func(curr,
121 TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
122 0, NULL);
123 }
124 }
125
126 spin_unlock_irqrestore(&pi_sems[sem_id].wait.lock, flags);
127 pi_sems[sem_id].used = 0;
128
129 return 0;
130}
131
132#endif
diff --git a/arch/i386/kernel/sem_syscalls.c b/arch/i386/kernel/sem_syscalls.c
deleted file mode 100644
index 4ca92c9be5..0000000000
--- a/arch/i386/kernel/sem_syscalls.c
+++ /dev/null
@@ -1,92 +0,0 @@
1/*
2 * SMP- and interrupt-safe semaphores, using system calls from user space,
3 * so that they work with the LSO. Uses semaphores as described in
4 * include/asm-i386/semaphore.h.
5 */
6
7#include <asm/semaphore.h>
8#include <linux/sched.h>
9
10#define MAX_SEMAPHORES 256
11
12struct semaphore sems[MAX_SEMAPHORES]; /* all sems */
13typedef int sema_id; /* Userspace ID of a semaphore */
14
15/* Initialize semaphores at boot time. */
16static int __init sema_boot_init(void)
17{
18 sema_id sem_id;
19
20 printk("Initializing semaphores...");
21 for (sem_id = 0; sem_id < MAX_SEMAPHORES; sem_id++)
22 sems[sem_id].used = 0;
23 printk(" done!\n");
24
25 return 0;
26}
27__initcall(sema_boot_init);
28
29/* Find a free semaphore and return. */
30asmlinkage long sys_sema_init (void)
31{
32 sema_id sem_id;
33
34 for (sem_id = 0; sem_id < MAX_SEMAPHORES; sem_id++) {
35 if (!cmpxchg(&sems[sem_id].used, 0, 1)) {
36 sema_init(&sems[sem_id], 1);
37 return sem_id;
38 }
39 }
40 return -ENOMEM;
41}
42
43asmlinkage long sys_down(sema_id sem_id)
44{
45 if (sem_id < 0 || sem_id >= MAX_SEMAPHORES)
46 return -EINVAL;
47
48 /* This allows for FIFO sems and gives others a chance... */
49 if (waitqueue_active(&sems[sem_id].wait))
50 __down(&sems[sem_id]);
51 else
52 down(&sems[sem_id]);
53 return 0;
54}
55
56asmlinkage long sys_up(sema_id sem_id)
57{
58 if (sem_id < 0 || sem_id >= MAX_SEMAPHORES)
59 return -EINVAL;
60
61 up(&sems[sem_id]);
62 return 0;
63}
64
65asmlinkage long sys_sema_free(sema_id sem_id)
66{
67 struct list_head *tmp, *next;
68 unsigned long flags;
69
70 if (sem_id < 0 || sem_id >= MAX_SEMAPHORES)
71 return -EINVAL;
72
73 spin_lock_irqsave(&sems[sem_id].wait.lock, flags);
74 if (waitqueue_active(&sems[sem_id].wait)) {
75 list_for_each_safe(tmp, next, &sems[sem_id].wait.task_list) {
76 wait_queue_t *curr = list_entry(tmp, wait_queue_t,
77 task_list);
78 list_del(tmp);
79 set_rt_flags((struct task_struct*)curr->private,
80 RT_F_EXIT_SEM);
81 curr->func(curr,
82 TASK_UNINTERRUPTIBLE | TASK_INTERRUPTIBLE,
83 0, NULL);
84 }
85 }
86
87 spin_unlock_irqrestore(&sems[sem_id].wait.lock, flags);
88 sems[sem_id].used = 0;
89
90 return 0;
91}
92
diff --git a/arch/i386/kernel/srp_sem_syscalls.c b/arch/i386/kernel/srp_sem_syscalls.c
deleted file mode 100644
index a07c36c7bf..0000000000
--- a/arch/i386/kernel/srp_sem_syscalls.c
+++ /dev/null
@@ -1,250 +0,0 @@
1#ifdef __KERNEL__
2
3/*
4 * Uniprocessor SRP "semaphores".
5 */
6
7#include <linux/sched.h>
8#include <linux/queuelock.h>
9#include <linux/sched_plugin.h>
10
11#define MAX_SRP_SEMAPHORES 256
12
13/* struct for uniprocessor SRP "semaphore" */
14struct srp_semaphore {
15 struct task_struct *pc_task; /* task representing prio ceil of sem */
16 int cpu; /* cpu associated with this "semaphore" and resource */
17 int claimed; /* is the resource claimed (ceiling should be used)? */
18 int used; /* is the semaphore being used? */
19};
20
21struct srp_semaphore srp_sems[MAX_SRP_SEMAPHORES]; /* all SRP sems */
22typedef int srp_sema_id; /* Userspace ID of a srp_semaphore */
23
24/* System-wide priority ceiling, represented as a pointer to a task. */
25DEFINE_PER_CPU(struct task_struct *, spc_tasks);
26DEFINE_PER_CPU(wait_queue_head_t, spc_waitqueues);
27
28/* Used to serialize access to SRP semaphores and system priority ceiling. */
29static queuelock_t srp_lock;
30
31/* Initialize SRP semaphores at boot time. */
32static int __init srp_sema_boot_init(void)
33{
34 srp_sema_id sem_id;
35 int i;
36
37 printk("Initializing SRP semaphores...");
38 for (sem_id = 0; sem_id < MAX_SRP_SEMAPHORES; sem_id++) {
39 srp_sems[sem_id].used = 0;
40 srp_sems[sem_id].claimed = 0;
41 srp_sems[sem_id].cpu = -1;
42 }
43 for (i = 0; i < NR_CPUS; i++) {
44 per_cpu(spc_tasks, i) = NULL;
45 init_waitqueue_head(&per_cpu(spc_waitqueues, i));
46 }
47 queue_lock_init(&srp_lock);
48 printk(" done!\n");
49
50 return 0;
51}
52__initcall(srp_sema_boot_init);
53
54/* Find a free semaphore and return. */
55asmlinkage long sys_srp_sema_init (void)
56{
57 srp_sema_id sem_id;
58
59 for (sem_id = 0; sem_id < MAX_SRP_SEMAPHORES; sem_id++) {
60 if (!cmpxchg(&srp_sems[sem_id].used, 0, 1)) {
61 srp_sems[sem_id].pc_task = NULL;
62 return sem_id;
63 }
64 }
65 return -ENOMEM;
66}
67
68/* SRP task priority comparison function. Smaller periods have highest
69 * priority, tie-break is PID.
70 */
71int srp_higher_prio(struct task_struct* first, struct task_struct* second)
72{
73 return !second || !is_realtime(second) ||
74 get_rt_period(first) < get_rt_period(second) ||
75 (get_rt_period(first) == get_rt_period(second) &&
76 first->pid < second->pid);
77}
78
79/* Adjust the system-wide priority ceiling if resource is claimed. */
80asmlinkage long sys_srp_down(srp_sema_id sem_id)
81{
82 unsigned long flags;
83 int cpu = smp_processor_id();
84
85 if (sem_id < 0 || sem_id >= MAX_SRP_SEMAPHORES ||
86 srp_sems[sem_id].cpu != cpu)
87 return -EINVAL;
88
89 queue_lock_irqsave(&srp_lock, flags);
90 srp_sems[sem_id].claimed = 1;
91 if (srp_higher_prio(srp_sems[sem_id].pc_task,
92 __get_cpu_var(spc_tasks))) {
93 __get_cpu_var(spc_tasks) = srp_sems[sem_id].pc_task;
94 }
95 queue_unlock_irqrestore(&srp_lock, flags);
96
97 return 0;
98}
99
100/* Adjust the system-wide priority ceiling if resource is freed. */
101asmlinkage long sys_srp_up(srp_sema_id sem_id)
102{
103 srp_sema_id sem_ctr;
104 struct list_head *tmp, *next;
105 unsigned long flags;
106 int cpu = smp_processor_id();
107
108 if (sem_id < 0 || sem_id >= MAX_SRP_SEMAPHORES ||
109 srp_sems[sem_id].cpu != cpu)
110 return -EINVAL;
111
112 queue_lock_irqsave(&srp_lock, flags);
113
114 /* Determine new system priority ceiling for this CPU. */
115 srp_sems[sem_id].claimed = 0;
116 __get_cpu_var(spc_tasks) = NULL;
117 for (sem_ctr = 0; sem_ctr < MAX_SRP_SEMAPHORES; sem_ctr++)
118 if (srp_sems[sem_ctr].used && srp_sems[sem_ctr].claimed &&
119 srp_sems[sem_ctr].cpu == cpu &&
120 srp_higher_prio(srp_sems[sem_ctr].pc_task,
121 __get_cpu_var(spc_tasks)))
122 __get_cpu_var(spc_tasks) = srp_sems[sem_ctr].pc_task;
123
124 /* Wake tasks on this CPU, if they exceed current ceiling. */
125 if (waitqueue_active(&__get_cpu_var(spc_waitqueues))) {
126 list_for_each_safe(tmp, next,
127 &__get_cpu_var(spc_waitqueues).task_list) {
128 wait_queue_t *curr = list_entry(tmp, wait_queue_t,
129 task_list);
130 set_rt_flags((struct task_struct*)curr->private,
131 RT_F_EXIT_SEM);
132
133 if (srp_higher_prio((struct task_struct*)curr->private,
134 __get_cpu_var(spc_tasks)))
135 curr->func(curr,
136 TASK_UNINTERRUPTIBLE |
137 TASK_INTERRUPTIBLE, 0, NULL);
138 }
139 }
140
141 queue_unlock_irqrestore(&srp_lock, flags);
142 return 0;
143}
144
145/* Indicate that task will use a resource associated with a given
146 * semaphore. Should be done *a priori* before RT task system is
147 * executed, so this does *not* update the system priority
148 * ceiling! (The ceiling would be meaningless anyway, as the SRP
149 * breaks without this a priori knowledge.)
150 */
151asmlinkage long sys_reg_task_srp_sem(srp_sema_id sem_id, pid_t t_pid)
152{
153 unsigned long flags;
154 struct pid *task_pid;
155 struct task_struct *t;
156
157 if (sem_id < 0 || sem_id >= MAX_SRP_SEMAPHORES)
158 return -EINVAL;
159
160 task_pid = find_get_pid(t_pid);
161 if (!task_pid)
162 return -EINVAL;
163
164 t = get_pid_task(task_pid, PIDTYPE_PID);
165 if (!t)
166 return -EINVAL;
167
168 queue_lock_irqsave(&srp_lock, flags);
169 if (srp_sems[sem_id].cpu == -1)
170 srp_sems[sem_id].cpu = get_partition(t);
171 else if (srp_sems[sem_id].cpu != get_partition(t)) {
172 queue_unlock_irqrestore(&srp_lock, flags);
173 return -EINVAL;
174 }
175 if (srp_higher_prio(t, srp_sems[sem_id].pc_task))
176 srp_sems[sem_id].pc_task = t;
177 queue_unlock_irqrestore(&srp_lock, flags);
178
179 return 0;
180}
181
182/* Wait for current task priority to exceed system-wide priority ceiling.
183 * Can be used to determine when it is safe to run a job after its release.
184 */
185void wait_until_exceed_spc(void)
186{
187 struct task_struct *tsk = current;
188 DECLARE_WAITQUEUE(wait, tsk);
189 unsigned long flags;
190
191 queue_lock_irqsave(&srp_lock, flags);
192 add_wait_queue_exclusive_locked(&__get_cpu_var(spc_waitqueues), &wait);
193 while(!srp_higher_prio(tsk, __get_cpu_var(spc_tasks))) {
194 tsk->state = TASK_UNINTERRUPTIBLE;
195 queue_unlock_irqrestore(&srp_lock, flags);
196 schedule();
197 queue_lock_irqsave(&srp_lock, flags);
198 }
199 remove_wait_queue_locked(&__get_cpu_var(spc_waitqueues), &wait);
200 queue_unlock_irqrestore(&srp_lock, flags);
201}
202
203/* Free semaphore, adjusting the system-wide priority ceiling if necessary. */
204asmlinkage long sys_srp_sema_free(srp_sema_id sem_id)
205{
206 srp_sema_id sem_ctr;
207 struct list_head *tmp, *next;
208 unsigned long flags;
209 int cpu = smp_processor_id();
210
211 if (sem_id < 0 || sem_id >= MAX_SRP_SEMAPHORES ||
212 srp_sems[sem_id].cpu != cpu)
213 return -EINVAL;
214
215 queue_lock_irqsave(&srp_lock, flags);
216 srp_sems[sem_id].claimed = 0;
217 srp_sems[sem_id].used = 0;
218
219 /* Determine new system priority ceiling for this CPU. */
220 __get_cpu_var(spc_tasks) = NULL;
221 for (sem_ctr = 0; sem_ctr < MAX_SRP_SEMAPHORES; sem_ctr++)
222 if (srp_sems[sem_ctr].used && srp_sems[sem_ctr].claimed &&
223 srp_sems[sem_ctr].cpu == cpu &&
224 srp_higher_prio(srp_sems[sem_ctr].pc_task,
225 __get_cpu_var(spc_tasks)))
226 __get_cpu_var(spc_tasks) = srp_sems[sem_ctr].pc_task;
227 srp_sems[sem_id].cpu = -1;
228
229 /* Wake tasks on this CPU, if they exceed current ceiling. */
230 if (waitqueue_active(&__get_cpu_var(spc_waitqueues))) {
231 list_for_each_safe(tmp, next,
232 &__get_cpu_var(spc_waitqueues).task_list) {
233 wait_queue_t *curr = list_entry(tmp, wait_queue_t,
234 task_list);
235 set_rt_flags((struct task_struct*)curr->private,
236 RT_F_EXIT_SEM);
237
238 if (srp_higher_prio((struct task_struct*)curr->private,
239 __get_cpu_var(spc_tasks)))
240 curr->func(curr,
241 TASK_UNINTERRUPTIBLE |
242 TASK_INTERRUPTIBLE, 0, NULL);
243 }
244 }
245
246 queue_unlock_irqrestore(&srp_lock, flags);
247 return 0;
248}
249
250#endif
generated by cgit v1.2.2 (git 2.25.0) at 2025-08-31 23:26:56 -0400