eb814cf1ad
BPF CI has revealed flakiness in the task_local_storage/exit_creds test. The failure point in CI [1] is that null_ptr_count is equal to 0, which indicates that the program hasn't run yet. This points to the kern_sync_rcu (sys_membarrier -> synchronize_rcu underneath) not waiting sufficiently. Indeed, synchronize_rcu only waits for read-side sections that started before the call. If the program execution starts *during* the synchronize_rcu invocation (due to, say, preemption), the test won't wait long enough. As a speculative fix, make the synchornize_rcu calls in a loop until an explicit run counter has gone up. [1]: https://github.com/kernel-patches/bpf/actions/runs/3268263235/jobs/5374940791 Signed-off-by: Delyan Kratunov <delyank@meta.com> Link: https://lore.kernel.org/r/156d4ef82275a074e8da8f4cffbd01b0c1466493.camel@meta.com Signed-off-by: Alexei Starovoitov <ast@kernel.org>