3  * linux/ipc/util.c
8  *            Occurs in several places in the IPC code.
10  * Nov 1999 - ipc helper functions, unified SMP locking
12  * Oct 2002 - One lock per IPC id. RCU ipc_free for lock-free grow_ary().
14  * Mar 2006 - support for audit of ipc object properties
20  * General sysv ipc locking scheme:
22  *          obtain the ipc object (kern_ipc_perm) by looking up the id in an idr
28  *	      acquire the ipc lock (kern_ipc_perm.lock) through
35  *	    drop the ipc lock, through ipc_unlock_object().
39  *	- creating, removing and iterating the existing entries in ipc
80  * ipc_init - initialise ipc subsystem
82  * The various sysv ipc resources (semaphores, messages and shared
109  * ipc_init_ids	- initialise ipc identifiers
110  * @ids: ipc identifier set
112  * Set up the sequence range to use for the ipc identifier range (limited
134  * @ids: ipc id table to iterate.
162  * ipc_findkey	- find a key in an ipc identifier set
163  * @ids: ipc identifier set
166  * Returns the locked pointer to the ipc structure if found or NULL
167  * otherwise. If key is found ipc points to the owning ipc structure
186  * Insert new IPC object into idr tree, and set sequence number and id
209 	 * and the lockless preparations for ipc operations can start.  in ipc_idr_alloc()
234  * ipc_addid - add an ipc identifier
235  * @ids: ipc identifier set
236  * @new: new ipc permission set
239  * Add an entry 'new' to the ipc ids idr. The permissions object is
300  * ipcget_new -	create a new ipc object
301  * @ns: ipc namespace
302  * @ids: ipc identifier set
321  * ipc_check_perms - check security and permissions for an ipc object
322  * @ns: ipc namespace
323  * @ipcp: ipc permission set
331  * On success, the ipc id is returned.
354  * ipcget_public - get an ipc object or create a new one
355  * @ns: ipc namespace
356  * @ids: ipc identifier set
365  * On success, the ipc id is returned.
387 		/* ipc object has been locked by ipc_findkey() */  in ipcget_public()
397 				 * ipc_check_perms returns the IPC id on  in ipcget_public()
410  * ipc_kht_remove - remove an ipc from the key hashtable
411  * @ids: ipc identifier set
412  * @ipcp: ipc perm structure containing the key to remove
425  * ipc_rmid - remove an ipc identifier
426  * @ids: ipc identifier set
427  * @ipcp: ipc perm structure containing the identifier to remove
452  * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
453  * @ids: ipc identifier set
454  * @ipcp: ipc perm structure containing the key to modify
480  * ipcperms - check ipc permissions
481  * @ns: ipc namespace
482  * @ipcp: ipc permission set
486  * to ipc resources. return 0 if allowed
517  * kernel_to_ipc64_perm	- convert kernel ipc permissions to user
519  * @out: new style ipc permissions
536  * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
537  * @in: new style ipc permissions
538  * @out: old style ipc permissions
556  * @ids: ipc identifier set
557  * @id: ipc id to look for
559  * Look for an id in the ipc ids idr and return associated ipc object.
562  * The ipc object is *not* locked on exit.
578  * @ids: ipc identifier set
579  * @id: ipc id to look for
581  * Similar to ipc_obtain_object_idr() but also checks the ipc object
585  * The ipc object is *not* locked on exit.
603  * @ids: ipc identifier set
604  * @ops: operations to be called on ipc object creation, permission checks
620  * ipc_update_perm - update the permissions of an ipc object
622  * @out: the permission of the ipc to set.
640  * ipcctl_obtain_check - retrieve an ipc object and check permissions
641  * @ns:  ipc namespace
642  * @ids:  the table of ids where to look for the ipc
643  * @id:   the id of the ipc to retrieve
652  *   - retrieves the ipc object with the given id in the given table.
654  *   - returns a pointer to the ipc object or otherwise, the corresponding
690  * ipc_parse_version - ipc call version
693  * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
723  * This routine locks the ipc structure found at least at position pos.
729 	struct kern_ipc_perm *ipc = NULL;  in sysvipc_find_ipc()  local
736 		ipc = idr_find(&ids->ipcs_idr, pos);  in sysvipc_find_ipc()
737 		if (ipc != NULL) {  in sysvipc_find_ipc()
739 			ipc_lock_object(ipc);  in sysvipc_find_ipc()
745 	return ipc;  in sysvipc_find_ipc()
752 	struct kern_ipc_perm *ipc = it;  in sysvipc_proc_next()  local
754 	/* If we had an ipc id locked before, unlock it */  in sysvipc_proc_next()
755 	if (ipc && ipc != SEQ_START_TOKEN)  in sysvipc_proc_next()
756 		ipc_unlock(ipc);  in sysvipc_proc_next()
762  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
763  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
787 	/* Find the (pos-1)th ipc */  in sysvipc_proc_start()
793 	struct kern_ipc_perm *ipc = it;  in sysvipc_proc_stop()  local
799 	if (ipc && ipc != SEQ_START_TOKEN)  in sysvipc_proc_stop()
800 		ipc_unlock(ipc);  in sysvipc_proc_stop()