[PATCH rcu 9/9] rcutorture: Stop right-shifting torture_random() return values

From: Paul E. McKenney
Date: Mon Jul 17 2023 - 14:21:12 EST


Now that torture_random() uses swahw32(), its callers no longer see
not-so-random low-order bits, as these are now swapped up into the upper
16 bits of the torture_random() function's return value. This commit
therefore removes the right-shifting of torture_random() return values.

Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
kernel/rcu/rcutorture.c | 6 +++---
1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c
index d291a1438c30..ade42d6a9d9b 100644
--- a/kernel/rcu/rcutorture.c
+++ b/kernel/rcu/rcutorture.c
@@ -1877,7 +1877,7 @@ static int
rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
{
int mask = rcutorture_extend_mask_max();
- unsigned long randmask1 = torture_random(trsp) >> 8;
+ unsigned long randmask1 = torture_random(trsp);
unsigned long randmask2 = randmask1 >> 3;
unsigned long preempts = RCUTORTURE_RDR_PREEMPT | RCUTORTURE_RDR_SCHED;
unsigned long preempts_irq = preempts | RCUTORTURE_RDR_IRQ;
@@ -1936,7 +1936,7 @@ rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
if (!((mask - 1) & mask))
return rtrsp; /* Current RCU reader not extendable. */
/* Bias towards larger numbers of loops. */
- i = (torture_random(trsp) >> 3);
+ i = torture_random(trsp);
i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
for (j = 0; j < i; j++) {
mask = rcutorture_extend_mask(*readstate, trsp);
@@ -2137,7 +2137,7 @@ static int rcu_nocb_toggle(void *arg)
toggle_fuzz = NSEC_PER_USEC;
do {
r = torture_random(&rand);
- cpu = (r >> 4) % (maxcpu + 1);
+ cpu = (r >> 1) % (maxcpu + 1);
if (r & 0x1) {
rcu_nocb_cpu_offload(cpu);
atomic_long_inc(&n_nocb_offload);
--
2.40.1