On Fri, Nov 14, 2025 at 12:25:03PM +0100, Eugenio Perez Martin wrote: > RCU is protecting that the address space pointer of the vq group is > not modified concurrently with the access. Ideally, this should be a > full lock, but just making sure that all accesses from the reader are > coherent is enough. Userspace should expect nothing if it uses the map > and modifies the vq group ASID at the same time anyway, but the kernel > needs to be sure that it does not see intermediate states. TBH, we > could move to a READ_ONCE / WRITE_ONCE, would that be more clear?
generally rcu itself does not need ONCE macros. these are for funky lockless things, and rcu can be seen as a kind of lock, after all. -- MST
