1 /* SPDX-License-Identifier: GPL-2.0-only */
2 #ifndef __LINUX_DEVM_HELPERS_H
3 #define __LINUX_DEVM_HELPERS_H
4
5 /*
6 * Functions which do automatically cancel operations or release resources upon
7 * driver detach.
8 *
9 * These should be helpful to avoid mixing the manual and devm-based resource
10 * management which can be source of annoying, rarely occurring,
11 * hard-to-reproduce bugs.
12 *
13 * Please take into account that devm based cancellation may be performed some
14 * time after the remove() is ran.
15 *
16 * Thus mixing devm and manual resource management can easily cause problems
17 * when unwinding operations with dependencies. IRQ scheduling a work in a queue
18 * is typical example where IRQs are often devm-managed and WQs are manually
19 * cleaned at remove(). If IRQs are not manually freed at remove() (and this is
20 * often the case when we use devm for IRQs) we have a period of time after
21 * remove() - and before devm managed IRQs are freed - where new IRQ may fire
22 * and schedule a work item which won't be cancelled because remove() was
23 * already ran.
24 */
25
26 #include <linux/device.h>
27 #include <linux/workqueue.h>
28
29 static inline void devm_delayed_work_drop(void *res)
30 {
31 cancel_delayed_work_sync(res);
32 }
33
34 /**
35 * devm_delayed_work_autocancel - Resource-managed delayed work allocation
36 * @dev: Device which lifetime work is bound to
37 * @w: Work item to be queued
38 * @worker: Worker function
39 *
40 * Initialize delayed work which is automatically cancelled when driver is
41 * detached. A few drivers need delayed work which must be cancelled before
42 * driver is detached to avoid accessing removed resources.
43 * devm_delayed_work_autocancel() can be used to omit the explicit
44 * cancellation when driver is detached.
45 */
46 static inline int devm_delayed_work_autocancel(struct device *dev,
47 struct delayed_work *w,
48 work_func_t worker)
49 {
50 INIT_DELAYED_WORK(w, worker);
51 return devm_add_action(dev, devm_delayed_work_drop, w);
52 }
53
54 static inline void devm_work_drop(void *res)
55 {
56 cancel_work_sync(res);
57 }
58
59 /**
60 * devm_work_autocancel - Resource-managed work allocation
61 * @dev: Device which lifetime work is bound to
62 * @w: Work to be added (and automatically cancelled)
63 * @worker: Worker function
64 *
65 * Initialize work which is automatically cancelled when driver is detached.
66 * A few drivers need to queue work which must be cancelled before driver
67 * is detached to avoid accessing removed resources.
68 * devm_work_autocancel() can be used to omit the explicit
69 * cancellation when driver is detached.
70 */
71 static inline int devm_work_autocancel(struct device *dev,
72 struct work_struct *w,
73 work_func_t worker)
74 {
75 INIT_WORK(w, worker);
76 return devm_add_action(dev, devm_work_drop, w);
77 }
78
79 #endif
80
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.