rcu: Rename struct rcu_gp_oldstate to rcu_gp_seq

The polled grace-period state structure rcu_gp_oldstate holds a snapshot
of the normal (and, on SMP, expedited) grace-period sequence numbers.
Upcoming changes store this structure in the callback segment list, where
the "oldstate" name reads poorly: there it represents the grace period a
segment is waiting on and is also compared against the current
grace-period state.

Rename struct rcu_gp_oldstate to the more neutral struct rcu_gp_seq, and
shorten its members rgos_norm and rgos_exp to norm and exp.  Local
variables and parameters of this type are renamed from rgosp/rgos to
gsp/gs accordingly.

While at it, provide a single definition of the structure in rcupdate.h
rather than separate Tiny-RCU and Tree-RCU definitions, and give it the
->exp field unconditionally.  Tiny RCU does not track expedited grace
periods and leaves ->exp unused, but a single definition that always has
->exp lets the shared callback code in rcu_segcblist.c reference it
without CONFIG_SMP guards, including on !SMP builds.

No functional change.

Signed-off-by: Puranjay Mohan <puranjay@kernel.org>
Reviewed-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

1 files changed, 12 insertions, 17 deletions

diff --git a/include/linux/rcutree.h b/include/linux/rcutree.h
index 9d2d7bd251d4..16a04202888b 100644
--- a/include/linux/rcutree.h
+++ b/include/linux/rcutree.h
@@ -38,12 +38,7 @@ void synchronize_rcu_expedited(void);
 void rcu_barrier(void);
 void rcu_momentary_eqs(void);
 
-struct rcu_gp_oldstate {
-	unsigned long rgos_norm;
-	unsigned long rgos_exp;
-};
-
-// Maximum number of rcu_gp_oldstate values corresponding to
+// Maximum number of rcu_gp_seq values corresponding to
 // not-yet-completed RCU grace periods.
 #define NUM_ACTIVE_RCU_POLL_FULL_OLDSTATE 4
 
@@ -60,29 +55,29 @@ struct rcu_gp_oldstate {
  * to a list header, allowing those structures to be slightly smaller.
  *
  * Note that equality is judged on a bitwise basis, so that an
- * @rcu_gp_oldstate structure with an already-completed state in one field
+ * @rcu_gp_seq structure with an already-completed state in one field
  * will compare not-equal to a structure with an already-completed state
- * in the other field.  After all, the @rcu_gp_oldstate structure is opaque
+ * in the other field.  After all, the @rcu_gp_seq structure is opaque
  * so how did such a situation come to pass in the first place?
  */
-static inline bool same_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp1,
-						   struct rcu_gp_oldstate *rgosp2)
+static inline bool same_state_synchronize_rcu_full(struct rcu_gp_seq *rgosp1,
+						   struct rcu_gp_seq *rgosp2)
 {
-	return rgosp1->rgos_norm == rgosp2->rgos_norm && rgosp1->rgos_exp == rgosp2->rgos_exp;
+	return rgosp1->norm == rgosp2->norm && rgosp1->exp == rgosp2->exp;
 }
 
 unsigned long start_poll_synchronize_rcu_expedited(void);
-void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp);
+void start_poll_synchronize_rcu_expedited_full(struct rcu_gp_seq *gsp);
 void cond_synchronize_rcu_expedited(unsigned long oldstate);
-void cond_synchronize_rcu_expedited_full(struct rcu_gp_oldstate *rgosp);
+void cond_synchronize_rcu_expedited_full(struct rcu_gp_seq *gsp);
 unsigned long get_state_synchronize_rcu(void);
-void get_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
+void get_state_synchronize_rcu_full(struct rcu_gp_seq *gsp);
 unsigned long start_poll_synchronize_rcu(void);
-void start_poll_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
+void start_poll_synchronize_rcu_full(struct rcu_gp_seq *gsp);
 bool poll_state_synchronize_rcu(unsigned long oldstate);
-bool poll_state_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
+bool poll_state_synchronize_rcu_full(struct rcu_gp_seq *gsp);
 void cond_synchronize_rcu(unsigned long oldstate);
-void cond_synchronize_rcu_full(struct rcu_gp_oldstate *rgosp);
+void cond_synchronize_rcu_full(struct rcu_gp_seq *gsp);
 
 #ifdef CONFIG_PROVE_RCU
 void rcu_irq_exit_check_preempt(void);