Root/ipc/util.h

Source at commit fbf123cd4cc0c097fe9a99c90109ebb2a5e94a50 created 7 years 11 months ago.
By Lars-Peter Clausen, dma: jz4740: Dequeue descriptor from active list before completing it
1/*
2 * linux/ipc/util.h
3 * Copyright (C) 1999 Christoph Rohland
4 *
5 * ipc helper functions (c) 1999 Manfred Spraul <manfred@colorfullife.com>
6 * namespaces support. 2006 OpenVZ, SWsoft Inc.
7 * Pavel Emelianov <xemul@openvz.org>
8 */
9
10#ifndef _IPC_UTIL_H
11#define _IPC_UTIL_H
12
13#include <linux/unistd.h>
14#include <linux/err.h>
15
16#define SEQ_MULTIPLIER (IPCMNI)
17
18void sem_init(void);
19void msg_init(void);
20void shm_init(void);
21
22struct ipc_namespace;
23
24#ifdef CONFIG_POSIX_MQUEUE
25extern void mq_clear_sbinfo(struct ipc_namespace *ns);
26extern void mq_put_mnt(struct ipc_namespace *ns);
27#else
28static inline void mq_clear_sbinfo(struct ipc_namespace *ns) { }
29static inline void mq_put_mnt(struct ipc_namespace *ns) { }
30#endif
31
32#ifdef CONFIG_SYSVIPC
33void sem_init_ns(struct ipc_namespace *ns);
34void msg_init_ns(struct ipc_namespace *ns);
35void shm_init_ns(struct ipc_namespace *ns);
36
37void sem_exit_ns(struct ipc_namespace *ns);
38void msg_exit_ns(struct ipc_namespace *ns);
39void shm_exit_ns(struct ipc_namespace *ns);
40#else
41static inline void sem_init_ns(struct ipc_namespace *ns) { }
42static inline void msg_init_ns(struct ipc_namespace *ns) { }
43static inline void shm_init_ns(struct ipc_namespace *ns) { }
44
45static inline void sem_exit_ns(struct ipc_namespace *ns) { }
46static inline void msg_exit_ns(struct ipc_namespace *ns) { }
47static inline void shm_exit_ns(struct ipc_namespace *ns) { }
48#endif
49
50struct ipc_rcu {
51    struct rcu_head rcu;
52    atomic_t refcount;
53} ____cacheline_aligned_in_smp;
54
55#define ipc_rcu_to_struct(p) ((void *)(p+1))
56
57/*
58 * Structure that holds the parameters needed by the ipc operations
59 * (see after)
60 */
61struct ipc_params {
62    key_t key;
63    int flg;
64    union {
65        size_t size; /* for shared memories */
66        int nsems; /* for semaphores */
67    } u; /* holds the getnew() specific param */
68};
69
70/*
71 * Structure that holds some ipc operations. This structure is used to unify
72 * the calls to sys_msgget(), sys_semget(), sys_shmget()
73 * . routine to call to create a new ipc object. Can be one of newque,
74 * newary, newseg
75 * . routine to call to check permissions for a new ipc object.
76 * Can be one of security_msg_associate, security_sem_associate,
77 * security_shm_associate
78 * . routine to call for an extra check if needed
79 */
80struct ipc_ops {
81    int (*getnew)(struct ipc_namespace *, struct ipc_params *);
82    int (*associate)(struct kern_ipc_perm *, int);
83    int (*more_checks)(struct kern_ipc_perm *, struct ipc_params *);
84};
85
86struct seq_file;
87struct ipc_ids;
88
89void ipc_init_ids(struct ipc_ids *);
90#ifdef CONFIG_PROC_FS
91void __init ipc_init_proc_interface(const char *path, const char *header,
92        int ids, int (*show)(struct seq_file *, void *));
93#else
94#define ipc_init_proc_interface(path, header, ids, show) do {} while (0)
95#endif
96
97#define IPC_SEM_IDS 0
98#define IPC_MSG_IDS 1
99#define IPC_SHM_IDS 2
100
101#define ipcid_to_idx(id) ((id) % SEQ_MULTIPLIER)
102#define ipcid_to_seqx(id) ((id) / SEQ_MULTIPLIER)
103#define IPCID_SEQ_MAX min_t(int, INT_MAX/SEQ_MULTIPLIER, USHRT_MAX)
104
105/* must be called with ids->rwsem acquired for writing */
106int ipc_addid(struct ipc_ids *, struct kern_ipc_perm *, int);
107
108/* must be called with ids->rwsem acquired for reading */
109int ipc_get_maxid(struct ipc_ids *);
110
111/* must be called with both locks acquired. */
112void ipc_rmid(struct ipc_ids *, struct kern_ipc_perm *);
113
114/* must be called with ipcp locked */
115int ipcperms(struct ipc_namespace *ns, struct kern_ipc_perm *ipcp, short flg);
116
117/* for rare, potentially huge allocations.
118 * both function can sleep
119 */
120void *ipc_alloc(int size);
121void ipc_free(void *ptr, int size);
122
123/*
124 * For allocation that need to be freed by RCU.
125 * Objects are reference counted, they start with reference count 1.
126 * getref increases the refcount, the putref call that reduces the recount
127 * to 0 schedules the rcu destruction. Caller must guarantee locking.
128 */
129void *ipc_rcu_alloc(int size);
130int ipc_rcu_getref(void *ptr);
131void ipc_rcu_putref(void *ptr, void (*func)(struct rcu_head *head));
132void ipc_rcu_free(struct rcu_head *head);
133
134struct kern_ipc_perm *ipc_lock(struct ipc_ids *, int);
135struct kern_ipc_perm *ipc_obtain_object(struct ipc_ids *ids, int id);
136
137void kernel_to_ipc64_perm(struct kern_ipc_perm *in, struct ipc64_perm *out);
138void ipc64_perm_to_ipc_perm(struct ipc64_perm *in, struct ipc_perm *out);
139int ipc_update_perm(struct ipc64_perm *in, struct kern_ipc_perm *out);
140struct kern_ipc_perm *ipcctl_pre_down_nolock(struct ipc_namespace *ns,
141                         struct ipc_ids *ids, int id, int cmd,
142                         struct ipc64_perm *perm, int extra_perm);
143
144#ifndef CONFIG_ARCH_WANT_IPC_PARSE_VERSION
145/* On IA-64, we always use the "64-bit version" of the IPC structures. */
146# define ipc_parse_version(cmd) IPC_64
147#else
148int ipc_parse_version(int *cmd);
149#endif
150
151extern void free_msg(struct msg_msg *msg);
152extern struct msg_msg *load_msg(const void __user *src, size_t len);
153extern struct msg_msg *copy_msg(struct msg_msg *src, struct msg_msg *dst);
154extern int store_msg(void __user *dest, struct msg_msg *msg, size_t len);
155
156extern void recompute_msgmni(struct ipc_namespace *);
157
158static inline int ipc_buildid(int id, int seq)
159{
160    return SEQ_MULTIPLIER * seq + id;
161}
162
163static inline int ipc_checkid(struct kern_ipc_perm *ipcp, int uid)
164{
165    return uid / SEQ_MULTIPLIER != ipcp->seq;
166}
167
168static inline void ipc_lock_object(struct kern_ipc_perm *perm)
169{
170    spin_lock(&perm->lock);
171}
172
173static inline void ipc_unlock_object(struct kern_ipc_perm *perm)
174{
175    spin_unlock(&perm->lock);
176}
177
178static inline void ipc_assert_locked_object(struct kern_ipc_perm *perm)
179{
180    assert_spin_locked(&perm->lock);
181}
182
183static inline void ipc_unlock(struct kern_ipc_perm *perm)
184{
185    ipc_unlock_object(perm);
186    rcu_read_unlock();
187}
188
189/*
190 * ipc_valid_object() - helper to sort out IPC_RMID races for codepaths
191 * where the respective ipc_ids.rwsem is not being held down.
192 * Checks whether the ipc object is still around or if it's gone already, as
193 * ipc_rmid() may have already freed the ID while the ipc lock was spinning.
194 * Needs to be called with kern_ipc_perm.lock held -- exception made for one
195 * checkpoint case at sys_semtimedop() as noted in code commentary.
196 */
197static inline bool ipc_valid_object(struct kern_ipc_perm *perm)
198{
199    return !perm->deleted;
200}
201
202struct kern_ipc_perm *ipc_obtain_object_check(struct ipc_ids *ids, int id);
203int ipcget(struct ipc_namespace *ns, struct ipc_ids *ids,
204            const struct ipc_ops *ops, struct ipc_params *params);
205void free_ipcs(struct ipc_namespace *ns, struct ipc_ids *ids,
206        void (*free)(struct ipc_namespace *, struct kern_ipc_perm *));
207#endif
208

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