Hi Greg, On 2018/11/22 18:21, Greg Kroah-Hartman wrote: > On Tue, Nov 20, 2018 at 10:34:19PM +0800, Gao Xiang wrote: >> There are two minor issues in the current freeze interface: >> >> 1) Freeze interfaces have not related with CONFIG_DEBUG_SPINLOCK, >> therefore fix the incorrect conditions; >> >> 2) For SMP platforms, it should also disable preemption before >> doing atomic_cmpxchg in case that some high priority tasks >> preempt between atomic_cmpxchg and disable_preempt, then spin >> on the locked refcount later. > > spinning on a refcount implies that you are trying to do your own type > of locking. Why not use the in-kernel locking api instead? It will > always do better than trying to do your own logic as the developers > there know locking across all types of cpus better than filesystem > developers :) It is because refcount also plays a role as a spinlock on a specific value (== EROFS_LOCKED_MAGIC), no need to introduce such a value since the spin window is small. Thanks, Gao Xiang > > thanks, > > greg k-h > _______________________________________________ devel mailing list devel@xxxxxxxxxxxxxxxxxxxxxx http://driverdev.linuxdriverproject.org/mailman/listinfo/driverdev-devel
