rcutorture: Increase visibility of forward-progress hangs

This commit adds a few pr_alert() calls to rcutorture's forward-progress
testing in order to better diagnose shutdown-time hangs.

Signed-off-by: Paul E. McKenney <paulmck@kernel.org>

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 00400aef58184396b9cc68b924050b87a6496081..fefc3fa1a9c2ac2a14bf9a8a9a4d40c8fdf36a8a 100644 (file)
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -2281,6 +2281,7 @@ static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
        unsigned long stopat;
        static DEFINE_TORTURE_RANDOM(trs);
 
+       pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
        if (!cur_ops->sync)
                return; // Cannot do need_resched() forward progress testing without ->sync.
        if (cur_ops->call && cur_ops->cb_barrier) {
@@ -2325,6 +2326,7 @@ static void rcu_torture_fwd_prog_nr(struct rcu_fwd *rfp,
        if (selfpropcb) {
                WRITE_ONCE(fcs.stop, 1);
                cur_ops->sync(); /* Wait for running CB to complete. */
+               pr_alert("%s: Waiting for CBs: %pS() %d\n", __func__, cur_ops->cb_barrier, rfp->rcu_fwd_id);
                cur_ops->cb_barrier(); /* Wait for queued callbacks. */
        }
 
@@ -2353,6 +2355,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
        unsigned long stopat;
        unsigned long stoppedat;
 
+       pr_alert("%s: Starting forward-progress test %d\n", __func__, rfp->rcu_fwd_id);
        if (READ_ONCE(rcu_fwd_emergency_stop))
                return; /* Get out of the way quickly, no GP wait! */
        if (!cur_ops->call)
@@ -2414,6 +2417,7 @@ static void rcu_torture_fwd_prog_cr(struct rcu_fwd *rfp)
        n_launders_cb_snap = READ_ONCE(rfp->n_launders_cb);
        cver = READ_ONCE(rcu_torture_current_version) - cver;
        gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
+       pr_alert("%s: Waiting for CBs: %pS() %d\n", __func__, cur_ops->cb_barrier, rfp->rcu_fwd_id);
        cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
        (void)rcu_torture_fwd_prog_cbfree(rfp);