Commit ffcc21a3 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

rcu-tasks: Maintain a count of tasks blocking RCU Tasks Trace grace period 



This commit maintains a new n_trc_holdouts counter that tracks the number
of tasks blocking the RCU Tasks grace period.  This counter is useful
for debugging, and its value has been added to a diagostic message.

Signed-off-by: default avatarPaul E. McKenney <paulmck@kernel.org>
Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com>
Cc: Eric Dumazet <edumazet@google.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Andrii Nakryiko <andrii@kernel.org>
Cc: Martin KaFai Lau <kafai@fb.com>
Cc: KP Singh <kpsingh@kernel.org>
parent 1a4a8153

kernel/rcu/tasks.h

+5 −1
Original line number Diff line number Diff line
@@ -1206,6 +1206,7 @@ static DEFINE_PER_CPU(bool, trc_ipi_to_cpu); 
static unsigned long n_heavy_reader_attempts;

static unsigned long n_heavy_reader_updates;

static unsigned long n_heavy_reader_ofl_updates;

static unsigned long n_trc_holdouts;



void call_rcu_tasks_trace(struct rcu_head *rhp, rcu_callback_t func);

DEFINE_RCU_TASKS(rcu_tasks_trace, rcu_tasks_wait_gp, call_rcu_tasks_trace,
@@ -1299,6 +1300,7 @@ static void trc_add_holdout(struct task_struct *t, struct list_head *bhp) 
	if (list_empty(&t->trc_holdout_list)) {

		get_task_struct(t);

		list_add(&t->trc_holdout_list, bhp);

		n_trc_holdouts++;

	}

}
@@ -1308,6 +1310,7 @@ static void trc_del_holdout(struct task_struct *t) 
	if (!list_empty(&t->trc_holdout_list)) {

		list_del_init(&t->trc_holdout_list);

		put_task_struct(t);

		n_trc_holdouts--;

	}

}
@@ -1760,7 +1763,8 @@ void show_rcu_tasks_trace_gp_kthread(void) 
{

	char buf[64];



	sprintf(buf, "h:%lu/%lu/%lu",

	sprintf(buf, "N%lu h:%lu/%lu/%lu",

		data_race(n_trc_holdouts),

		data_race(n_heavy_reader_ofl_updates),

		data_race(n_heavy_reader_updates),

		data_race(n_heavy_reader_attempts));