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
108  * ipc_init_ids	- initialise ipc identifiers
109  * @ids: ipc identifier set
111  * 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
213 	 * and the lockless preparations for ipc operations can start.  in ipc_idr_alloc()
263  * ipc_addid - add an ipc identifier
264  * @ids: ipc identifier set
265  * @new: new ipc permission set
268  * Add an entry 'new' to the ipc ids idr. The permissions object is
329  * ipcget_new -	create a new ipc object
330  * @ns: ipc namespace
331  * @ids: ipc identifier set
350  * ipc_check_perms - check security and permissions for an ipc object
351  * @ns: ipc namespace
352  * @ipcp: ipc permission set
360  * On success, the ipc id is returned.
383  * ipcget_public - get an ipc object or create a new one
384  * @ns: ipc namespace
385  * @ids: ipc identifier set
394  * On success, the ipc id is returned.
416 		/* ipc object has been locked by ipc_findkey() */  in ipcget_public()
426 				 * ipc_check_perms returns the IPC id on  in ipcget_public()
439  * ipc_kht_remove - remove an ipc from the key hashtable
440  * @ids: ipc identifier set
441  * @ipcp: ipc perm structure containing the key to remove
454  * ipc_rmid - remove an ipc identifier
455  * @ids: ipc identifier set
456  * @ipcp: ipc perm structure containing the identifier to remove
481  * ipc_set_key_private - switch the key of an existing ipc to IPC_PRIVATE
482  * @ids: ipc identifier set
483  * @ipcp: ipc perm structure containing the key to modify
509  * ipcperms - check ipc permissions
510  * @ns: ipc namespace
511  * @ipcp: ipc permission set
515  * to ipc resources. return 0 if allowed
546  * kernel_to_ipc64_perm	- convert kernel ipc permissions to user
548  * @out: new style ipc permissions
565  * ipc64_perm_to_ipc_perm - convert new ipc permissions to old
566  * @in: new style ipc permissions
567  * @out: old style ipc permissions
585  * @ids: ipc identifier set
586  * @id: ipc id to look for
588  * Look for an id in the ipc ids idr and return associated ipc object.
591  * The ipc object is *not* locked on exit.
607  * @ids: ipc identifier set
608  * @id: ipc id to look for
610  * Similar to ipc_obtain_object_idr() but also checks the ipc object
614  * The ipc object is *not* locked on exit.
632  * @ids: ipc identifier set
633  * @ops: operations to be called on ipc object creation, permission checks
649  * ipc_update_perm - update the permissions of an ipc object
651  * @out: the permission of the ipc to set.
669  * ipcctl_obtain_check - retrieve an ipc object and check permissions
670  * @ns:  ipc namespace
671  * @ids:  the table of ids where to look for the ipc
672  * @id:   the id of the ipc to retrieve
681  *   - retrieves the ipc object with the given id in the given table.
683  *   - returns a pointer to the ipc object or otherwise, the corresponding
719  * ipc_parse_version - ipc call version
722  * Return IPC_64 for new style IPC and IPC_OLD for old style IPC.
752  * This routine locks the ipc structure found at least at position pos.
757 	struct kern_ipc_perm *ipc;  in sysvipc_find_ipc()  local
762 		ipc = idr_find(&ids->ipcs_idr, id);  in sysvipc_find_ipc()
763 		if (ipc != NULL)  in sysvipc_find_ipc()
767 	ipc = NULL;  in sysvipc_find_ipc()
772 		ipc = idr_find(&ids->ipcs_idr, pos);  in sysvipc_find_ipc()
773 		if (ipc != NULL) {  in sysvipc_find_ipc()
775 			ipc_lock_object(ipc);  in sysvipc_find_ipc()
781 	return ipc;  in sysvipc_find_ipc()
788 	struct kern_ipc_perm *ipc = it;  in sysvipc_proc_next()  local
790 	/* If we had an ipc id locked before, unlock it */  in sysvipc_proc_next()
791 	if (ipc && ipc != SEQ_START_TOKEN)  in sysvipc_proc_next()
792 		ipc_unlock(ipc);  in sysvipc_proc_next()
798  * File positions: pos 0 -> header, pos n -> ipc id = n - 1.
799  * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.
823 	/* Find the (pos-1)th ipc */  in sysvipc_proc_start()
829 	struct kern_ipc_perm *ipc = it;  in sysvipc_proc_stop()  local
835 	if (ipc && ipc != SEQ_START_TOKEN)  in sysvipc_proc_stop()
836 		ipc_unlock(ipc);  in sysvipc_proc_stop()