| 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 | * 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(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 |