On Tue, 24 Jul 2007, Oliver Neukum wrote: > Am Montag 23 Juli 2007 schrieb Alan Stern: > > Now here's an idea which might work. Can we require every caller of > > device_add() to hold some existing device's semaphore? Normally it > > would be the semaphore of the new device's parent, but it could be a > > higher ancestor. There even could be a single "root" semaphore for > > drivers registering a top-level device with no parent. > > What prevents us from having a device addition semaphore? > Adding device is not critical to performance, is it?
It would create a locking order violation. Many drivers hold a device semaphore while registering a child device, so they would acquire your new semaphore while holding a device sem. But the PM core needs to prevent registration while calling suspend() methods, so it would need to acquire the device sems while holding your new semaphore. Alan Stern - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
