include/linux/devm-helpers.h

0001 /* SPDX-License-Identifier: GPL-2.0-only */
0002 #ifndef __LINUX_DEVM_HELPERS_H
0003 #define __LINUX_DEVM_HELPERS_H
0004
0005 /*
0006  * Functions which do automatically cancel operations or release resources upon
0007  * driver detach.
0008  *
0009  * These should be helpful to avoid mixing the manual and devm-based resource
0010  * management which can be source of annoying, rarely occurring,
0011  * hard-to-reproduce bugs.
0012  *
0013  * Please take into account that devm based cancellation may be performed some
0014  * time after the remove() is ran.
0015  *
0016  * Thus mixing devm and manual resource management can easily cause problems
0017  * when unwinding operations with dependencies. IRQ scheduling a work in a queue
0018  * is typical example where IRQs are often devm-managed and WQs are manually
0019  * cleaned at remove(). If IRQs are not manually freed at remove() (and this is
0020  * often the case when we use devm for IRQs) we have a period of time after
0021  * remove() - and before devm managed IRQs are freed - where new IRQ may fire
0022  * and schedule a work item which won't be cancelled because remove() was
0023  * already ran.
0024  */
0025
0026 #include <linux/device.h>
0027 #include <linux/workqueue.h>
0028
0029 static inline void devm_delayed_work_drop(void *res)
0030 {
0031     cancel_delayed_work_sync(res);
0032 }
0033
0034 /**
0035  * devm_delayed_work_autocancel - Resource-managed delayed work allocation
0036  * @dev:    Device which lifetime work is bound to
0037  * @w:      Work item to be queued
0038  * @worker: Worker function
0039  *
0040  * Initialize delayed work which is automatically cancelled when driver is
0041  * detached. A few drivers need delayed work which must be cancelled before
0042  * driver is detached to avoid accessing removed resources.
0043  * devm_delayed_work_autocancel() can be used to omit the explicit
0044  * cancelleation when driver is detached.
0045  */
0046 static inline int devm_delayed_work_autocancel(struct device *dev,
0047                            struct delayed_work *w,
0048                            work_func_t worker)
0049 {
0050     INIT_DELAYED_WORK(w, worker);
0051     return devm_add_action(dev, devm_delayed_work_drop, w);
0052 }
0053
0054 static inline void devm_work_drop(void *res)
0055 {
0056     cancel_work_sync(res);
0057 }
0058
0059 /**
0060  * devm_work_autocancel - Resource-managed work allocation
0061  * @dev:    Device which lifetime work is bound to
0062  * @w:      Work to be added (and automatically cancelled)
0063  * @worker: Worker function
0064  *
0065  * Initialize work which is automatically cancelled when driver is detached.
0066  * A few drivers need to queue work which must be cancelled before driver
0067  * is detached to avoid accessing removed resources.
0068  * devm_work_autocancel() can be used to omit the explicit
0069  * cancelleation when driver is detached.
0070  */
0071 static inline int devm_work_autocancel(struct device *dev,
0072                        struct work_struct *w,
0073                        work_func_t worker)
0074 {
0075     INIT_WORK(w, worker);
0076     return devm_add_action(dev, devm_work_drop, w);
0077 }
0078
0079 #endif