On 04/19/2013 12:13 PM, Arnd Bergmann wrote: > On Friday 19 April 2013, Lars-Peter Clausen wrote: > >> This is rather ugly and unnecessary and non of the current users of >> of_dma_controller_free() check it's return value anyway. Instead protect the >> list by a mutex. The mutex will be held as long as a request operation is in >> progress. So if of_dma_controller_free() is called while a request operation >> is >> in progress it will be put to sleep and only wake up once the request >> operation >> has finished. >> >> This means that it is no longer possible to register or unregister OF DMA >> controllers from a context where it's not possible to sleep. But I doubt that >> we'll ever need this. >> >> Also rename of_dma_get_controller back to of_dma_find_controller. >> >> Signed-off-by: Lars-Peter Clausen <l...@metafoo.de> > > I guess we could also fix it by turning the reference count into a proper > kref with kref_put calling the destructor, but your solution seems to solve > the problem just as well.
Well, It's not only about the of_dma struct, e.g. the of_dma's of_dma_data field usually points to some driver allocated data. If we do not block in of_dma_controller_free() this data might be freed while the controller is still in use. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
