[PATCH rcu 12/18] rcu: Make rcu_gp_init() and rcu_gp_fqs_loop noinline to conserve stack

[Paul E. McKenney]

The kbuild test project found an oversized stack frame in rcu_gp_kthread()
for some kernel configurations.  This oversizing was due to a very large
amount of inlining, which is unnecessary due to the fact that this code
executes infrequently.  This commit therefore marks rcu_gp_init() and
rcu_gp_fqs_loop noinline_for_stack to conserve stack space.

Reported-by: kernel test robot <lkp@xxxxxxxxx>
Tested-by: Rong Chen <rong.a.chen@xxxxxxxxx>
[ paulmck: noinline_for_stack per Nathan Chancellor. ]
Reviewed-by: Nathan Chancellor <nathan@xxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
 kernel/rcu/tree.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index bc6ccf0ba3b24..e472c78036011 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1739,7 +1739,7 @@ static void rcu_strict_gp_boundary(void *unused)
 /*
  * Initialize a new grace period.  Return false if no grace period required.
  */
-static bool rcu_gp_init(void)
+static noinline_for_stack bool rcu_gp_init(void)
 {
 	unsigned long firstseq;
 	unsigned long flags;
@@ -1933,7 +1933,7 @@ static void rcu_gp_fqs(bool first_time)
 /*
  * Loop doing repeated quiescent-state forcing until the grace period ends.
  */
-static void rcu_gp_fqs_loop(void)
+static noinline_for_stack void rcu_gp_fqs_loop(void)
 {
 	bool first_gp_fqs;
 	int gf = 0;
-- 
2.31.1.189.g2e36527f23