1/*
2 *  ICSWX and ACOP/PID Management
3 *
4 *  Copyright (C) 2011 Anton Blanchard, IBM Corp. <anton@samba.org>
5 *
6 *  This program is free software; you can redistribute it and/or
7 *  modify it under the terms of the GNU General Public License
8 *  as published by the Free Software Foundation; either version
9 *  2 of the License, or (at your option) any later version.
10 *
11 */
12
13#include <linux/sched.h>
14#include <linux/kernel.h>
15#include <linux/errno.h>
16#include <linux/types.h>
17#include <linux/mm.h>
18#include <linux/spinlock.h>
19#include <linux/idr.h>
20#include <linux/module.h>
21#include "icswx.h"
22
23#define COP_PID_MIN (COP_PID_NONE + 1)
24#define COP_PID_MAX (0xFFFF)
25
26static DEFINE_SPINLOCK(mmu_context_acop_lock);
27static DEFINE_IDA(cop_ida);
28
29static int new_cop_pid(struct ida *ida, int min_id, int max_id,
30		       spinlock_t *lock)
31{
32	int index;
33	int err;
34
35again:
36	if (!ida_pre_get(ida, GFP_KERNEL))
37		return -ENOMEM;
38
39	spin_lock(lock);
40	err = ida_get_new_above(ida, min_id, &index);
41	spin_unlock(lock);
42
43	if (err == -EAGAIN)
44		goto again;
45	else if (err)
46		return err;
47
48	if (index > max_id) {
49		spin_lock(lock);
50		ida_remove(ida, index);
51		spin_unlock(lock);
52		return -ENOMEM;
53	}
54
55	return index;
56}
57
58int get_cop_pid(struct mm_struct *mm)
59{
60	int pid;
61
62	if (mm->context.cop_pid == COP_PID_NONE) {
63		pid = new_cop_pid(&cop_ida, COP_PID_MIN, COP_PID_MAX,
64				  &mmu_context_acop_lock);
65		if (pid >= 0)
66			mm->context.cop_pid = pid;
67	}
68	return mm->context.cop_pid;
69}
70
71int disable_cop_pid(struct mm_struct *mm)
72{
73	int free_pid = COP_PID_NONE;
74
75	if ((!mm->context.acop) && (mm->context.cop_pid != COP_PID_NONE)) {
76		free_pid = mm->context.cop_pid;
77		mm->context.cop_pid = COP_PID_NONE;
78	}
79	return free_pid;
80}
81
82void free_cop_pid(int free_pid)
83{
84	spin_lock(&mmu_context_acop_lock);
85	ida_remove(&cop_ida, free_pid);
86	spin_unlock(&mmu_context_acop_lock);
87}
88