linux-kernel - [tip: core/rcu] rcutorture: Make in-kernel-loop testing more brutal

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Message-ID: <157252290769.29376.3589481983002794153.tip-bot2@tip-bot2>
Date:   Thu, 31 Oct 2019 11:55:07 -0000
From:   "tip-bot2 for Paul E. McKenney" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     "Paul E. McKenney" <paulmck@...nel.org>,
        Ingo Molnar <mingo@...nel.org>, Borislav Petkov <bp@...en8.de>,
        linux-kernel@...r.kernel.org
Subject: [tip: core/rcu] rcutorture: Make in-kernel-loop testing more brutal

The following commit has been merged into the core/rcu branch of tip:

Commit-ID:     fbbd5e358cecb5fa490550ace66463517a7577e8
Gitweb:        https://git.kernel.org/tip/fbbd5e358cecb5fa490550ace66463517a7577e8
Author:        Paul E. McKenney <paulmck@...nel.org>
AuthorDate:    Thu, 15 Aug 2019 11:43:53 -07:00
Committer:     Paul E. McKenney <paulmck@...nel.org>
CommitterDate: Sat, 05 Oct 2019 11:50:18 -07:00

rcutorture: Make in-kernel-loop testing more brutal

The rcu_torture_fwd_prog_nr() tests the ability of RCU to tolerate
in-kernel busy loops.  It invokes rcu_torture_fwd_prog_cond_resched()
within its delay loop, which, in PREEMPT && NO_HZ_FULL kernels results
in the occasional direct call to schedule().  Now, this direct call to
schedule() is appropriate for call_rcu() flood testing, in which either
the kernel should restrain itself or userspace transitions will supply
the needed restraint.  But in pure in-kernel loops, the occasional
cond_resched() should do the job.

This commit therefore makes rcu_torture_fwd_prog_nr() use cond_resched()
instead of rcu_torture_fwd_prog_cond_resched() in order to increase the
brutality of this aspect of rcutorture testing.

Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/rcu/rcutorture.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index 5ac4672..df1caa9 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1806,7 +1806,7 @@ static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
 		udelay(10);
 		cur_ops->readunlock(idx);
 		if (!fwd_progress_need_resched || need_resched())
-			rcu_torture_fwd_prog_cond_resched(1);
+			cond_resched();
 	}
 	(*tested_tries)++;
 	if (!time_before(jiffies, stopat) &&