srcu: Make SRCU readers use ->srcu_ctrs for counter selection
This commit causes SRCU readers to use ->srcu_ctrs for counter
selection instead of ->srcu_idx. This takes another step towards
array-indexing-free SRCU readers.
[ paulmck: Apply kernel test robot feedback. ]
Co-developed-by: Z qiang <qiang.zhang1211@gmail.com> Signed-off-by: Z qiang <qiang.zhang1211@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Tested-by: kernel test robot <oliver.sang@intel.com> Cc: Alexei Starovoitov <ast@kernel.org> Cc: Andrii Nakryiko <andrii@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Kent Overstreet <kent.overstreet@linux.dev> Cc: <bpf@vger.kernel.org> Signed-off-by: Boqun Feng <boqun.feng@gmail.com>