On 09/09/2013 12:00 PM, Laurent Pinchart wrote: > Hi Hans, > > On Monday 09 September 2013 11:07:43 Hans Verkuil wrote: >> On 09/06/2013 12:33 AM, Sylwester Nawrocki wrote: >>> On 08/07/2013 07:49 PM, Hans Verkuil wrote: >>>> On 08/07/2013 06:49 PM, Sylwester Nawrocki wrote: >>>>> On 08/02/2013 03:00 PM, Hans Verkuil wrote: >>>>>> On 08/02/2013 02:27 PM, Sylwester Nawrocki wrote: > > [snip] > >>> The main issue as I see it is that we need to track both driver remove() >>> and struct device .release() calls and free resources only when last of >>> them executes. Data structures which are referenced in fops must not be >>> freed in remove() and we cannot use dev_get_drvdata() in fops, e.g. not >>> protected with device_lock(). >> >> You can do all that by returning 0 if probe() was partially successful (i.e. >> one or more, but not all, nodes were created successfully) by doing what I >> described above. I don't see another way that doesn't introduce a race >> condition. > > But isn't this just plain wrong ? If probing fails, I don't see how returning > success could be a good idea. Well, the nodes that are created are working fine. So it's partially OK :-) That said, yes it would be better if it could safely clean up and return an error. But it is better than returning an error and introducing a race condition. >> That doesn't mean that there isn't one, it's just that I don't know of a >> better way of doing this. > > We might need support from the device core. > I do come back to my main question: has anyone actually experienced this error in a realistic scenario? Other than in very low-memory situations I cannot imagine this happening. I'm not sure whether you want to spend a lot of time trying to fix this all perfectly. That's why I am suggesting just unregistering everything and returning 0 in probe(). Not ideal, but at least it's safe (as far as I can tell). Regards, Hans -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
