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 
devm_delayed_work_drop(void * res)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  * cancelleation when driver is detached.
45  */
devm_delayed_work_autocancel(struct device * dev,struct delayed_work * w,work_func_t worker)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 
devm_work_drop(void * res)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  * cancelleation when driver is detached.
70  */
devm_work_autocancel(struct device * dev,struct work_struct * w,work_func_t worker)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