On 19/07/2019 19:04:21+0000, Trent Piepho wrote: > On Fri, 2019-07-19 at 02:57 +0000, Anson Huang wrote: > > > > > I do worry that handling the irq before the rtc device is registered could still > > > result in a crash. From what I saw, the irq path in snvs only uses driver state > > > members that are fully initialized for the most part, and the allocated but > > > unregistered data->rtc is only used in one call to rtc_update_irq(), which > > > appears to be ok with this. > > > > > > But it is not that hard to imagine that something could go into the rtc core > > > that assumes call like rtc_update_irq() are only made on registered devices. > > > > > > If there was a way to do it, I think allocating the irq in a masked state and > > > then unmasking it as part of the final registration call to make the device go > > > live would be a safer and more general pattern. > > > > It makes sense, I think we can just move the devm_request_irq() to after rtc_register_device(), > > It will make sure everything is ready before IRQ is enabled. Will send out a V2 patch. > > That will mean registering the rtc, then unregistering it if the irq > request fails. More of a pain to write this failure path. > > Alexandre, is it part of rtc core design that rtc_update_irq() might be > called on a rtc device that is properly allocated, but not registered > yet? Yes, the main reason of the change of API was exactly to handle this. -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
