From aced1a8244189e4016b1fdef249b3297c09f626d Mon Sep 17 00:00:00 2001
From: Sven Dziadek <s9svdzia@stud.uni-saarland.de>
Date: Mon, 16 Apr 2012 21:18:09 +0200
Subject: P-FP: make PCP available to userspace

Prior to that it was only used internally for DPCP
---
 include/litmus/fdso.h |   4 +-
 litmus/fdso.c         |   1 +
 litmus/sched_pfp.c    | 140 ++++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 144 insertions(+), 1 deletion(-)

diff --git a/include/litmus/fdso.h b/include/litmus/fdso.h
index 2b0537ce7260..f2115b83f1e4 100644
--- a/include/litmus/fdso.h
+++ b/include/litmus/fdso.h
@@ -24,7 +24,9 @@ typedef enum  {
 	MPCP_VS_SEM	= 3,
 	DPCP_SEM	= 4,
 
-	MAX_OBJ_TYPE	= 4
+	PCP_SEM         = 5,
+
+	MAX_OBJ_TYPE	= 5
 } obj_type_t;
 
 struct inode_obj_id {
diff --git a/litmus/fdso.c b/litmus/fdso.c
index 04c0b55e41d3..cd85b9cd9a0a 100644
--- a/litmus/fdso.c
+++ b/litmus/fdso.c
@@ -26,6 +26,7 @@ static const struct fdso_ops* fdso_ops[] = {
 	&generic_lock_ops, /* MPCP_SEM */
 	&generic_lock_ops, /* MPCP_VS_SEM */
 	&generic_lock_ops, /* DPCP_SEM */
+	&generic_lock_ops, /* PCP_SEM */
 };
 
 static int fdso_create(void** obj_ref, obj_type_t type, void* __user config)
diff --git a/litmus/sched_pfp.c b/litmus/sched_pfp.c
index d5dd78d941c6..42d17b0c08fd 100644
--- a/litmus/sched_pfp.c
+++ b/litmus/sched_pfp.c
@@ -950,6 +950,8 @@ static struct litmus_lock* pfp_new_mpcp(int vspin)
 
 
 struct pcp_semaphore {
+	struct litmus_lock litmus_lock;
+
 	struct list_head ceiling;
 
 	/* current resource holder */
@@ -962,6 +964,12 @@ struct pcp_semaphore {
 	int on_cpu;
 };
 
+static inline struct pcp_semaphore* pcp_from_lock(struct litmus_lock* lock)
+{
+	return container_of(lock, struct pcp_semaphore, litmus_lock);
+}
+
+
 struct pcp_state {
 	struct list_head system_ceiling;
 
@@ -1203,6 +1211,123 @@ static void pcp_init_semaphore(struct pcp_semaphore* sem, int cpu)
 	sem->on_cpu = cpu;
 }
 
+int pfp_pcp_lock(struct litmus_lock* l)
+{
+	struct task_struct* t = current;
+	struct pcp_semaphore *sem = pcp_from_lock(l);
+
+	int eprio = effective_agent_priority(get_priority(t));
+	int from  = get_partition(t);
+	int to    = sem->on_cpu;
+
+	if (!is_realtime(t) || from != to)
+		return -EPERM;
+
+	preempt_disable();
+
+	pcp_raise_ceiling(sem, eprio);
+
+	preempt_enable();
+
+	return 0;
+}
+
+int pfp_pcp_unlock(struct litmus_lock* l)
+{
+	struct task_struct *t = current;
+	struct pcp_semaphore *sem = pcp_from_lock(l);
+
+	int err = 0;
+
+	preempt_disable();
+
+	if (sem->on_cpu != smp_processor_id() || sem->owner != t) {
+		err = -EINVAL;
+		goto out;
+	}
+
+	/* give it back */
+	pcp_lower_ceiling(sem);
+
+out:
+	preempt_enable();
+
+	return err;
+}
+
+int pfp_pcp_open(struct litmus_lock* l, void* __user config)
+{
+	struct task_struct *t = current;
+	struct pcp_semaphore *sem = pcp_from_lock(l);
+
+	int cpu, eprio;
+
+	if (!is_realtime(t))
+		/* we need to know the real-time priority */
+		return -EPERM;
+
+	if (get_user(cpu, (int*) config))
+		return -EFAULT;
+
+	/* make sure the resource location matches */
+	if (cpu != sem->on_cpu)
+		return -EINVAL;
+
+	eprio = effective_agent_priority(get_priority(t));
+
+	pcp_update_prio_ceiling(sem, eprio);
+
+	return 0;
+}
+
+int pfp_pcp_close(struct litmus_lock* l)
+{
+	struct task_struct *t = current;
+	struct pcp_semaphore *sem = pcp_from_lock(l);
+
+	int owner = 0;
+
+	preempt_disable();
+
+	if (sem->on_cpu == smp_processor_id())
+		owner = sem->owner == t;
+
+	preempt_enable();
+
+	if (owner)
+		pfp_pcp_unlock(l);
+
+	return 0;
+}
+
+void pfp_pcp_free(struct litmus_lock* lock)
+{
+	kfree(pcp_from_lock(lock));
+}
+
+
+static struct litmus_lock_ops pfp_pcp_lock_ops = {
+	.close  = pfp_pcp_close,
+	.lock   = pfp_pcp_lock,
+	.open	= pfp_pcp_open,
+	.unlock = pfp_pcp_unlock,
+	.deallocate = pfp_pcp_free,
+};
+
+
+static struct litmus_lock* pfp_new_pcp(int on_cpu)
+{
+	struct pcp_semaphore* sem;
+
+	sem = kmalloc(sizeof(*sem), GFP_KERNEL);
+	if (!sem)
+		return NULL;
+
+	sem->litmus_lock.ops = &pfp_pcp_lock_ops;
+	pcp_init_semaphore(sem, on_cpu);
+
+	return &sem->litmus_lock;
+}
 
 /* ******************** DPCP support ********************** */
 
@@ -1459,6 +1584,21 @@ static long pfp_allocate_lock(struct litmus_lock **lock, int type,
 		} else
 			err = -ENOMEM;
 		break;
+
+        case PCP_SEM:
+		/* Priority Ceiling Protocol */
+		if (get_user(cpu, (int*) config))
+			return -EFAULT;
+
+		if (!cpu_online(cpu))
+			return -EINVAL;
+
+		*lock = pfp_new_pcp(cpu);
+		if (*lock)
+			err = 0;
+		else
+			err = -ENOMEM;
+		break;
 	};
 
 	return err;
-- 
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