Messages in this thread | | | Date | Tue, 18 May 2021 19:39:38 -0500 | From | Rob Herring <> | Subject | Re: [PATCH v2 0/5] Add devm helper for work-queue initialization |
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On Tue, May 18, 2021 at 03:31:37PM +0300, Matti Vaittinen wrote: > This series adds new devm_work_autocancel() helper. > > Many drivers which use work-queues must ensure the work is not queued when > driver is detached. Often this is done by ensuring new work is not added and > then calling cancel_work_sync() at remove(). In many cases this also requires > cleanup at probe error path - which is easy to forget (or get wrong). > > Also the "by ensuring new work is not added" has a gotcha. > > It is not strange to see devm managed IRQs scheduling work. > Mixing this with manual wq clean-up is hard to do correctly because the > devm is likely to free the IRQ only after the remove() is ran. So manual > wq cancellation and devm-based IRQ management do not mix well - there is > a short(?) time-window after the wq clean-up when IRQs are still not > freed and may schedule new work. > > When both WQs and IRQs are managed by devm things are likely to just > work. WQs should be initialized before IRQs (when IRQs need to schedule > work) and devm unwinds things in "FILO" order.
Wouldn't it be better to convert drivers to use threaded IRQ handlers?
> > This series implements wq cancellation on top of devm and replaces > the obvious cases where only thing remove call-back in a driver does is > cancelling the work. There might be other cases where we could switch > more than just work cancellation to use managed version and thus get rid > of remove or mixed (manual and devm) resource management. > > Changelog v2: > - rebased on v5.13-rc2 > - split the extcon-max8997 change into two. First a simple, > back-portable fix for omitting IRQ freeing at error path, second > being the devm-simpification which does not need backporting. > > --- > > Matti Vaittinen (5): > devm-helpers: Add resource managed version of work init > extcon: extcon-max14577: Fix potential work-queue cancellation race > extcon: extcon-max77693.c: Fix potential work-queue cancellation race > extcon: extcon-max8997: Fix IRQ freeing at error path > extcon: extcon-max8997: Simplify driver using devm > > drivers/extcon/extcon-max14577.c | 16 ++++-------- > drivers/extcon/extcon-max77693.c | 17 ++++-------- > drivers/extcon/extcon-max8997.c | 45 +++++++++++--------------------- > include/linux/devm-helpers.h | 25 ++++++++++++++++++ > 4 files changed, 50 insertions(+), 53 deletions(-) > > > base-commit: d07f6ca923ea0927a1024dfccafc5b53b61cfecc > -- > 2.25.4 > > > -- > Matti Vaittinen, Linux device drivers > ROHM Semiconductors, Finland SWDC > Kiviharjunlenkki 1E > 90220 OULU > FINLAND > > ~~~ "I don't think so," said Rene Descartes. Just then he vanished ~~~ > Simon says - in Latin please. > ~~~ "non cogito me" dixit Rene Descarte, deinde evanescavit ~~~ > Thanks to Simon Glass for the translation =]
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