We are clearing the gp_flags before we check if a grace period is in progress.
If a grace period is in progress, we return after incorrectly clearing the
gp_flags. The code comments say that this is highly unlikely, but just to be
safe this commit moves the clearing of gp_flags to after the check for grace
period in progress.

Signed-off-by: Pranith Kumar <bobby.pr...@gmail.com>
---
 kernel/rcu/tree.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 044946e..b14cecd 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -1605,7 +1605,6 @@ static int rcu_gp_init(struct rcu_state *rsp)
                raw_spin_unlock_irq(&rnp->lock);
                return 0;
        }
-       ACCESS_ONCE(rsp->gp_flags) = 0; /* Clear all flags: New grace period. */
 
        if (WARN_ON_ONCE(rcu_gp_in_progress(rsp))) {
                /*
@@ -1616,6 +1615,8 @@ static int rcu_gp_init(struct rcu_state *rsp)
                return 0;
        }
 
+       ACCESS_ONCE(rsp->gp_flags) = 0; /* Clear all flags: New grace period. */
+
        /* Advance to a new grace period and initialize state. */
        record_gp_stall_check_time(rsp);
        /* Record GP times before starting GP, hence smp_store_release(). */
-- 
2.0.0.rc2

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