On Fri, 6 Nov 2009 14:22:49 +0100, Arnd Bergmann wrote: > On Friday 06 November 2009, Jean Delvare wrote: > > I'm not sure why we need to hold the mutex here? My understanding is > > that watchdog_data_mutex protects watchdog_data_list and each > > watchdog's kref. And the above code doesn't touch either. > > > > What I am more worried about is why ident is declared static. This > > looks like a bug to me. Instead of abusing watchdog_data_mutex to > > workaround this, I'd rather remove the "static". I guess that the > > current code happens to work because neither data->revision nor > > nowayout can change over time, but this looks needlessly fragile. > > > > Hans, any comment? > > The data copied into the watchdog_info data structure is completely > static. To make that clearer, I'd suggest moving it outside of > the ioctl function, and initializing it from fschmd_init. > Then it becomes obvious that the mutex is not needed to protect it. Thinking about it some more... The driver supports the case where several chips are present on the system. I don't think we've ever seen this, but it is possible in theory. In this case, each chip would have its data->revision, and then the watchdog_info data structure is no longer static. We would need one watchdog_info data structure per fschmd_data. Whether allocating and initializing them at device probing time makes sense, I'm not so sure... I doubt this ioctl is performance-critical, so generating the data on-the-fly sounds quite sane to me. -- Jean Delvare _______________________________________________ lm-sensors mailing list lm-sensors@xxxxxxxxxxxxxx http://lists.lm-sensors.org/mailman/listinfo/lm-sensors
