1 // SPDX-License-Identifier: GPL-2.0-only
4  * Copyright (C) 2004-2005 Red Hat, Inc. All rights reserved.
10  * Round-robin path selector.
13 #include <linux/device-mapper.h>
15 #include "dm-path-selector.h"
20 #define DM_MSG_PREFIX "multipath round-robin"
25  *---------------------------------------------------------------
26  * Path-handling code, paths are held in lists
27  *---------------------------------------------------------------
40 		list_del(&pi->list);  in free_paths()
46  *---------------------------------------------------------------
47  * Round-robin selector
48  *---------------------------------------------------------------
61 		INIT_LIST_HEAD(&s->valid_paths);  in alloc_selector()
62 		INIT_LIST_HEAD(&s->invalid_paths);  in alloc_selector()
63 		spin_lock_init(&s->lock);  in alloc_selector()
75 		return -ENOMEM;  in rr_create()
77 	ps->context = s;  in rr_create()
83 	struct selector *s = ps->context;  in rr_destroy()
85 	free_paths(&s->valid_paths);  in rr_destroy()
86 	free_paths(&s->invalid_paths);  in rr_destroy()
88 	ps->context = NULL;  in rr_destroy()
104 			pi = path->pscontext;  in rr_status()
105 			DMEMIT("%u ", pi->repeat_count);  in rr_status()
124 	struct selector *s = ps->context;  in rr_add_path()
131 		*error = "round-robin ps: incorrect number of arguments";  in rr_add_path()
132 		return -EINVAL;  in rr_add_path()
137 		*error = "round-robin ps: invalid repeat count";  in rr_add_path()
138 		return -EINVAL;  in rr_add_path()
149 		*error = "round-robin ps: Error allocating path context";  in rr_add_path()
150 		return -ENOMEM;  in rr_add_path()
153 	pi->path = path;  in rr_add_path()
154 	pi->repeat_count = repeat_count;  in rr_add_path()
156 	path->pscontext = pi;  in rr_add_path()
158 	spin_lock_irqsave(&s->lock, flags);  in rr_add_path()
159 	list_add_tail(&pi->list, &s->valid_paths);  in rr_add_path()
160 	spin_unlock_irqrestore(&s->lock, flags);  in rr_add_path()
168 	struct selector *s = ps->context;  in rr_fail_path()
169 	struct path_info *pi = p->pscontext;  in rr_fail_path()
171 	spin_lock_irqsave(&s->lock, flags);  in rr_fail_path()
172 	list_move(&pi->list, &s->invalid_paths);  in rr_fail_path()
173 	spin_unlock_irqrestore(&s->lock, flags);  in rr_fail_path()
179 	struct selector *s = ps->context;  in rr_reinstate_path()
180 	struct path_info *pi = p->pscontext;  in rr_reinstate_path()
182 	spin_lock_irqsave(&s->lock, flags);  in rr_reinstate_path()
183 	list_move(&pi->list, &s->valid_paths);  in rr_reinstate_path()
184 	spin_unlock_irqrestore(&s->lock, flags);  in rr_reinstate_path()
192 	struct selector *s = ps->context;  in rr_select_path()
195 	spin_lock_irqsave(&s->lock, flags);  in rr_select_path()
196 	if (!list_empty(&s->valid_paths)) {  in rr_select_path()
197 		pi = list_entry(s->valid_paths.next, struct path_info, list);  in rr_select_path()
198 		list_move_tail(&pi->list, &s->valid_paths);  in rr_select_path()
200 	spin_unlock_irqrestore(&s->lock, flags);  in rr_select_path()
202 	return pi ? pi->path : NULL;  in rr_select_path()
206 	.name = "round-robin",
242 MODULE_DESCRIPTION(DM_NAME " round-robin multipath path selector");
243 MODULE_AUTHOR("Sistina Software <dm-devel@redhat.com>");