On Tue, May 07, 2019 at 04:56:05PM -0700, Dan Williams wrote: > The devm_add_action() facility allows a resource allocation routine to > add custom devm semantics. One such user is devm_memremap_pages(). > > There is now a need to manually trigger devm_memremap_pages_release(). > Introduce devm_release_action() so the release action can be triggered > via a new devm_memunmap_pages() api in a follow-on change. > > Cc: Logan Gunthorpe <[email protected]> > Cc: Bjorn Helgaas <[email protected]> > Cc: Christoph Hellwig <[email protected]> > Cc: Greg Kroah-Hartman <[email protected]> > Cc: "Rafael J. Wysocki" <[email protected]> > Reviewed-by: Ira Weiny <[email protected]> > Signed-off-by: Dan Williams <[email protected]> > --- > drivers/base/devres.c | 24 +++++++++++++++++++++++- > include/linux/device.h | 1 + > 2 files changed, 24 insertions(+), 1 deletion(-) > > diff --git a/drivers/base/devres.c b/drivers/base/devres.c > index e038e2b3b7ea..0bbb328bd17f 100644 > --- a/drivers/base/devres.c > +++ b/drivers/base/devres.c > @@ -755,10 +755,32 @@ void devm_remove_action(struct device *dev, void > (*action)(void *), void *data) > > WARN_ON(devres_destroy(dev, devm_action_release, devm_action_match, > &devres)); > - > } > EXPORT_SYMBOL_GPL(devm_remove_action); > > +/** > + * devm_release_action() - release previously added custom action > + * @dev: Device that owns the action > + * @action: Function implementing the action > + * @data: Pointer to data passed to @action implementation > + * > + * Releases and removes instance of @action previously added by > + * devm_add_action(). Both action and data should match one of the > + * existing entries. > + */ > +void devm_release_action(struct device *dev, void (*action)(void *), void > *data) > +{ > + struct action_devres devres = { > + .data = data, > + .action = action, > + }; > + > + WARN_ON(devres_release(dev, devm_action_release, devm_action_match, > + &devres));
What does WARN_ON help here? are we going to start getting syzbot reports of this happening? How can this fail? thanks, greg k-h
