The following commit has been merged into the core/rcu branch of tip: Commit-ID: 62ae19511f1efbe9f57346ca1f45e13b061a56ff Gitweb: https://git.kernel.org/tip/62ae19511f1efbe9f57346ca1f45e13b061a56ff Author: Paul E. McKenney <[email protected]> AuthorDate: Sat, 21 Mar 2020 19:52:20 -07:00 Committer: Paul E. McKenney <[email protected]> CommitterDate: Mon, 27 Apr 2020 11:01:16 -07:00
rcu: Mark rcu_state.gp_seq to detect more concurrent writes The rcu_state structure's gp_seq field is only to be modified by the RCU grace-period kthread, which is single-threaded. This commit therefore enlists KCSAN's help in enforcing this restriction. This commit applies KCSAN-specific primitives, so cannot go upstream until KCSAN does. Signed-off-by: Paul E. McKenney <[email protected]> --- kernel/rcu/tree.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index 0132bc6..183b9cf 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -1230,7 +1230,7 @@ static bool rcu_start_this_gp(struct rcu_node *rnp_start, struct rcu_data *rdp, trace_rcu_this_gp(rnp, rdp, gp_seq_req, TPS("NoGPkthread")); goto unlock_out; } - trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("newreq")); + trace_rcu_grace_period(rcu_state.name, data_race(rcu_state.gp_seq), TPS("newreq")); ret = true; /* Caller must wake GP kthread. */ unlock_out: /* Push furthest requested GP to leaf node and rcu_data structure. */ @@ -1519,6 +1519,7 @@ static bool rcu_gp_init(void) record_gp_stall_check_time(); /* Record GP times before starting GP, hence rcu_seq_start(). */ rcu_seq_start(&rcu_state.gp_seq); + ASSERT_EXCLUSIVE_WRITER(rcu_state.gp_seq); trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("start")); raw_spin_unlock_irq_rcu_node(rnp); @@ -1805,6 +1806,7 @@ static void rcu_gp_cleanup(void) /* Declare grace period done, trace first to use old GP number. */ trace_rcu_grace_period(rcu_state.name, rcu_state.gp_seq, TPS("end")); rcu_seq_end(&rcu_state.gp_seq); + ASSERT_EXCLUSIVE_WRITER(rcu_state.gp_seq); rcu_state.gp_state = RCU_GP_IDLE; /* Check for GP requests since above loop. */ rdp = this_cpu_ptr(&rcu_data);
