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(dwork: 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 | */ |
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(work: 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 | */ |
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 | |