From: Joel Fernandes (Google) Date: Fri, 19 Jun 2020 01:36:40 +0000 (-0400) Subject: rcu/trace: Use gp_seq_req in acceleration's rcu_grace_period tracepoint X-Git-Tag: v5.10-rc1~84^2^2~3^2~18 X-Git-Url: https://git.kernel.dk/?a=commitdiff_plain;h=a7886e899fd8334a03d37e66ad10295d175725ea;p=linux-2.6-block.git rcu/trace: Use gp_seq_req in acceleration's rcu_grace_period tracepoint During acceleration of CB, the rsp's gp_seq is rcu_seq_snap'd. This is the value used for acceleration - it is the value of gp_seq at which it is safe the execute all callbacks in the callback list. The rdp's gp_seq is not very useful for this scenario. Make rcu_grace_period report the gp_seq_req instead as it allows one to reason about how the acceleration works. Signed-off-by: Joel Fernandes (Google) Signed-off-by: Paul E. McKenney --- diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index eb36779697ca..896912034982 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1483,9 +1483,10 @@ static bool rcu_accelerate_cbs(struct rcu_node *rnp, struct rcu_data *rdp) /* Trace depending on how much we were able to accelerate. */ if (rcu_segcblist_restempty(&rdp->cblist, RCU_WAIT_TAIL)) - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccWaitCB")); + trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccWaitCB")); else - trace_rcu_grace_period(rcu_state.name, rdp->gp_seq, TPS("AccReadyCB")); + trace_rcu_grace_period(rcu_state.name, gp_seq_req, TPS("AccReadyCB")); + return ret; }