linux-kernel - [PATCH rcu 1/5] scftorture: Allow zero weight to exclude an smp_call

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Date:   Wed, 15 Sep 2021 16:41:37 -0700
From:   "Paul E. McKenney" <paulmck@...nel.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, kernel-team@...com, mingo@...nel.org,
        jiangshanlai@...il.com, akpm@...ux-foundation.org,
        mathieu.desnoyers@...icios.com, josh@...htriplett.org,
        tglx@...utronix.de, peterz@...radead.org, rostedt@...dmis.org,
        dhowells@...hat.com, edumazet@...gle.com, fweisbec@...il.com,
        oleg@...hat.com, joel@...lfernandes.org,
        "Paul E. McKenney" <paulmck@...nel.org>
Subject: [PATCH rcu 1/5] scftorture: Allow zero weight to exclude an smp_call_function*() category

This commit reworks the weighting calculations to allow zero to
be specified to diable a given weight.  For example, specifying the
scftorture.weight_resched=0 kernel boot parameter without specifying a
non-zero value for any of the other scftorture.weight_* parameters would
provide the default weights for the others, but would refrain from doing
any resched-based IPIs.

Signed-off-by: Paul E. McKenney <paulmck@...nel.org>
---
 kernel/scftorture.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/kernel/scftorture.c b/kernel/scftorture.c
index 64a08288b1a6..bc3f8e26345c 100644
--- a/kernel/scftorture.c
+++ b/kernel/scftorture.c
@@ -553,18 +553,18 @@ static int __init scf_torture_init(void)
 
 	scftorture_print_module_parms("Start of test");
 
-	if (weight_resched == -1 &&
-	    weight_single == -1 && weight_single_rpc == -1 && weight_single_wait == -1 &&
-	    weight_many == -1 && weight_many_wait == -1 &&
-	    weight_all == -1 && weight_all_wait == -1) {
-		weight_resched1 = 2 * nr_cpu_ids;
-		weight_single1 = 2 * nr_cpu_ids;
-		weight_single_rpc1 = 2 * nr_cpu_ids;
-		weight_single_wait1 = 2 * nr_cpu_ids;
-		weight_many1 = 2;
-		weight_many_wait1 = 2;
-		weight_all1 = 1;
-		weight_all_wait1 = 1;
+	if (weight_resched <= 0 &&
+	    weight_single <= 0 && weight_single_rpc <= 0 && weight_single_wait <= 0 &&
+	    weight_many <= 0 && weight_many_wait <= 0 &&
+	    weight_all <= 0 && weight_all_wait <= 0) {
+		weight_resched1 = weight_resched == 0 ? 0 : 2 * nr_cpu_ids;
+		weight_single1 = weight_single == 0 ? 0 : 2 * nr_cpu_ids;
+		weight_single_rpc1 = weight_single_rpc == 0 ? 0 : 2 * nr_cpu_ids;
+		weight_single_wait1 = weight_single_wait == 0 ? 0 : 2 * nr_cpu_ids;
+		weight_many1 = weight_many == 0 ? 0 : 2;
+		weight_many_wait1 = weight_many_wait == 0 ? 0 : 2;
+		weight_all1 = weight_all == 0 ? 0 : 1;
+		weight_all_wait1 = weight_all_wait == 0 ? 0 : 1;
 	} else {
 		if (weight_resched == -1)
 			weight_resched1 = 0;
-- 
2.31.1.189.g2e36527f23