LXR linux/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
  29static 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 */
  46static 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
  54static 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 */
  71static 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