On Wed, 2 Nov 2005, Greg KH wrote: > > > Your only requirement is that it is outside of your local > > > device structure so that you can syncronize things. > > > > Obviously :-) I suppose the reason why I need a semaphore and can't use a > > spinlock is that the call to kref_put in disconnect() must be protected by > > the lock, and the release() function called by kref_put might sleep. Is > > that > > right ? Is there another reason ? > > Hm, I think kref_put might sleep, but I am not positive. Try it with a > spinlock held and see if the kernel complains (after enabling the sleep > warning options in the DEBUG kernel options.)
kref_put itself doesn't sleep, but it might call the release routine and _that_ routine might sleep. It's also generally true when opening a file or disconnecting a device, that you have to do several things (more than just kref_put) that might sleep. Hence a semaphore is the appropriate sort of mutex. Alan Stern ------------------------------------------------------- SF.Net email is sponsored by: Tame your development challenges with Apache's Geronimo App Server. Download it for free - -and be entered to win a 42" plasma tv or your very own Sony(tm)PSP. Click here to play: http://sourceforge.net/geronimo.php _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
