On Wed, May 08, 2019 at 10:18:41AM -0700, Stanislav Fomichev wrote: > Right now we are not using rcu api correctly: we pass __rcu pointers > to bpf_prog_array_xyz routines but don't use rcu_dereference on them > (see bpf_prog_array_delete_safe and bpf_prog_array_copy in particular). > Instead of sprinkling rcu_dereferences, let's just get rid of those > __rcu annotations and move rcu handling to a higher level. > > It looks like all those routines are called from the rcu update > side and we can use simple rcu_dereference_protected to get a > reference that is valid as long as we hold a mutex (i.e. no other > updater can change the pointer, no need for rcu read section and > there should not be a use-after-free problem). > > To be fair, there is currently no issue with the existing approach > since the calls are mutex-protected, pointer values don't change, > __rcu annotations are ignored. But it's still nice to use proper api. > > The series fixes the following sparse warnings: Absolutely not. please fix it properly. Removing annotations is not a fix.
