include/linux/devm-helpers.h

   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 #endif