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A few drivers which need a work-queue must cancel work at driver detach. Some of those implement remove() solely for this purpose. Help drivers to avoid unnecessary remove and error-branch implementation by adding managed verision of work initialization. This will also help drivers to avoid mixing manual and devm based unwinding when other resources are handled by devm. Signed-off-by: Matti Vaittinen <matti.vaittinen@fi.rohmeurope.com> Reviewed-by: Krzysztof Kozlowski <krzysztof.kozlowski@canonical.com> Reviewed-by: Hans de Goede <hdegoede@redhat.com> Link: https://lore.kernel.org/r/94ff4175e7f2ff134ed2fa7d6e7641005cc9784b.1623146580.git.matti.vaittinen@fi.rohmeurope.com Signed-off-by: Hans de Goede <hdegoede@redhat.com>
80 lines
2.7 KiB
C
80 lines
2.7 KiB
C
/* SPDX-License-Identifier: GPL-2.0-only */
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#ifndef __LINUX_DEVM_HELPERS_H
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#define __LINUX_DEVM_HELPERS_H
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/*
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* Functions which do automatically cancel operations or release resources upon
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* driver detach.
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*
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* These should be helpful to avoid mixing the manual and devm-based resource
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* management which can be source of annoying, rarely occurring,
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* hard-to-reproduce bugs.
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*
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* Please take into account that devm based cancellation may be performed some
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* time after the remove() is ran.
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*
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* Thus mixing devm and manual resource management can easily cause problems
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* when unwinding operations with dependencies. IRQ scheduling a work in a queue
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* is typical example where IRQs are often devm-managed and WQs are manually
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* cleaned at remove(). If IRQs are not manually freed at remove() (and this is
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* often the case when we use devm for IRQs) we have a period of time after
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* remove() - and before devm managed IRQs are freed - where new IRQ may fire
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* and schedule a work item which won't be cancelled because remove() was
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* already ran.
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*/
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#include <linux/device.h>
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#include <linux/workqueue.h>
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static inline void devm_delayed_work_drop(void *res)
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{
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cancel_delayed_work_sync(res);
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}
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/**
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* devm_delayed_work_autocancel - Resource-managed delayed work allocation
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* @dev: Device which lifetime work is bound to
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* @w: Work item to be queued
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* @worker: Worker function
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*
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* Initialize delayed work which is automatically cancelled when driver is
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* detached. A few drivers need delayed work which must be cancelled before
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* driver is detached to avoid accessing removed resources.
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* devm_delayed_work_autocancel() can be used to omit the explicit
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* cancelleation when driver is detached.
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*/
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static inline int devm_delayed_work_autocancel(struct device *dev,
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struct delayed_work *w,
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work_func_t worker)
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{
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INIT_DELAYED_WORK(w, worker);
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return devm_add_action(dev, devm_delayed_work_drop, w);
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}
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static inline void devm_work_drop(void *res)
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{
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cancel_work_sync(res);
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}
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/**
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* devm_work_autocancel - Resource-managed work allocation
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* @dev: Device which lifetime work is bound to
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* @w: Work to be added (and automatically cancelled)
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* @worker: Worker function
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*
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* Initialize work which is automatically cancelled when driver is detached.
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* A few drivers need to queue work which must be cancelled before driver
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* is detached to avoid accessing removed resources.
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* devm_work_autocancel() can be used to omit the explicit
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* cancelleation when driver is detached.
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*/
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static inline int devm_work_autocancel(struct device *dev,
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struct work_struct *w,
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work_func_t worker)
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{
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INIT_WORK(w, worker);
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return devm_add_action(dev, devm_work_drop, w);
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}
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#endif
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