rcu: Handle obsolete references to TINY_PREEMPT_RCU

 * read-side critical section that would block in a !PREEMPT kernel.

 * But if you want the full story, read on!

 *

 * In non-preemptible RCU implementations (TREE_RCU and TINY_RCU), it

 * is illegal to block while in an RCU read-side critical section.  In

 * preemptible RCU implementations (TREE_PREEMPT_RCU and TINY_PREEMPT_RCU)

 * in CONFIG_PREEMPT kernel builds, RCU read-side critical sections may

 * be preempted, but explicit blocking is illegal.  Finally, in preemptible

 * RCU implementations in real-time (with -rt patchset) kernel builds,

 * RCU read-side critical sections may be preempted and they may also

 * block, but only when acquiring spinlocks that are subject to priority

 * inheritance.

 * In non-preemptible RCU implementations (TREE_RCU and TINY_RCU),

 * it is illegal to block while in an RCU read-side critical section.

 * In preemptible RCU implementations (TREE_PREEMPT_RCU) in CONFIG_PREEMPT

 * kernel builds, RCU read-side critical sections may be preempted,

 * but explicit blocking is illegal.  Finally, in preemptible RCU

 * implementations in real-time (with -rt patchset) kernel builds, RCU

 * read-side critical sections may be preempted and they may also block, but

 * only when acquiring spinlocks that are subject to priority inheritance.

 */

static inline void rcu_read_lock(void)

{

	def_bool TREE_PREEMPT_RCU

	help

	  This option enables preemptible-RCU code that is common between

	  the TREE_PREEMPT_RCU and TINY_PREEMPT_RCU implementations.

	  TREE_PREEMPT_RCU and, in the old days, TINY_PREEMPT_RCU.

config RCU_STALL_COMMON

	def_bool ( TREE_RCU || TREE_PREEMPT_RCU || RCU_TRACE )