[PATCH v6 06/46] percpu_rwlock: Rearrange the read-lock code to fastpath nested percpu readers

If we are dealing with a nester percpu reader, we can optimize away quite a few costly operations. Improve that fastpath further, by avoiding the unnecessary addition and subtraction of 'READER_PRESENT' to reader_refcnt, by rearranging the code a bit. Signed-off-by: Srivatsa S. Bhat ---

[PATCH v6 06/46] percpu_rwlock: Rearrange the read-lock code to fastpath nested percpu readers

If we are dealing with a nester percpu reader, we can optimize away quite a few costly operations. Improve that fastpath further, by avoiding the unnecessary addition and subtraction of 'READER_PRESENT' to reader_refcnt, by rearranging the code a bit. Signed-off-by: Srivatsa S. Bhat