Commit 58b5c203 authored by Manfred Spraul's avatar Manfred Spraul Committed by Andrew Morton
Browse files

ipc/util.c: cleanup and improve sysvipc_find_ipc() 

sysvipc_find_ipc() can be simplified further:

- It uses a for() loop to locate the next entry in the idr.
  This can be replaced with idr_get_next().

- It receives two parameters (pos - which is actually
  an idr index and not a position, and new_pos, which
  is really a position).
  One parameter is sufficient.

Link: https://lore.kernel.org/all/20210903052020.3265-3-manfred@colorfullife.com/
Link: https://lkml.kernel.org/r/20220805115733.104763-1-manfred@colorfullife.com


Signed-off-by: default avatarManfred Spraul <manfred@colorfullife.com>
Acked-by: default avatarDavidlohr Bueso <dave@stgolabs.net>
Acked-by: default avatarWaiman Long <longman@redhat.com>
Cc: "Eric W . Biederman" <ebiederm@xmission.com>
Cc: <1vier1@web.de>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent 765f2bf0

ipc/util.c

+32 −21
Original line number Diff line number Diff line
@@ -782,28 +782,37 @@ struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s) 
	return iter->pid_ns;

}



/*

 * This routine locks the ipc structure found at least at position pos.

/**

 * sysvipc_find_ipc - Find and lock the ipc structure based on seq pos

 * @ids: ipc identifier set

 * @pos: expected position

 *

 * The function finds an ipc structure, based on the sequence file

 * position @pos. If there is no ipc structure at position @pos, then

 * the successor is selected.

 * If a structure is found, then it is locked (both rcu_read_lock() and

 * ipc_lock_object()) and  @pos is set to the position needed to locate

 * the found ipc structure.

 * If nothing is found (i.e. EOF), @pos is not modified.

 *

 * The function returns the found ipc structure, or NULL at EOF.

 */

static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos,

					      loff_t *new_pos)

static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos)

{

	struct kern_ipc_perm *ipc = NULL;

	int max_idx = ipc_get_maxidx(ids);

	int tmpidx;

	struct kern_ipc_perm *ipc;



	if (max_idx == -1 || pos > max_idx)

		goto out;

	/* convert from position to idr index -> "-1" */

	tmpidx = *pos - 1;



	for (; pos <= max_idx; pos++) {

		ipc = idr_find(&ids->ipcs_idr, pos);

	ipc = idr_get_next(&ids->ipcs_idr, &tmpidx);

	if (ipc != NULL) {

		rcu_read_lock();

		ipc_lock_object(ipc);

			break;

		}



		/* convert from idr index to position  -> "+1" */

		*pos = tmpidx + 1;

	}

out:

	*new_pos = pos + 1;

	return ipc;

}
@@ -817,11 +826,13 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) 
	if (ipc && ipc != SEQ_START_TOKEN)

		ipc_unlock(ipc);



	return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos);

	/* Next -> search for *pos+1 */

	(*pos)++;

	return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos);

}



/*

 * File positions: pos 0 -> header, pos n -> ipc id = n - 1.

 * File positions: pos 0 -> header, pos n -> ipc idx = n - 1.

 * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START.

 */

static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos)
@@ -846,8 +857,8 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) 
	if (*pos == 0)

		return SEQ_START_TOKEN;



	/* Find the (pos-1)th ipc */

	return sysvipc_find_ipc(ids, *pos - 1, pos);

	/* Otherwise return the correct ipc structure */

	return sysvipc_find_ipc(ids, pos);

}



static void sysvipc_proc_stop(struct seq_file *s, void *it)