torture: Seed torture_random_state on CPU

paulmckrcu · paulmckrcu · commit 95f93e97ed0f · 2023-01-03T17:52:54.000-08:00
The DEFINE_TORTURE_RANDOM_PERCPU() macro defines per-CPU random-number
generators for torture testing, but the seeds for each CPU's instance
will be identical if they are first used at the same time.  This commit
therefore adds the CPU number to the mix when reseeding.

Signed-off-by: Paul E. McKenney &lt;paulmck@kernel.org&gt;
diff --git a/kernel/torture.c b/kernel/torture.c
@@ -450,7 +450,7 @@ unsigned long
 torture_random(struct torture_random_state *trsp)
 {
 	if (--trsp->trs_count < 0) {
-		trsp->trs_state += (unsigned long)local_clock();
+		trsp->trs_state += (unsigned long)local_clock() + raw_smp_processor_id();
 		trsp->trs_count = TORTURE_RANDOM_REFRESH;
 	}
 	trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +

Original file line number	Diff line number	Diff line change
`@@ -450,7 +450,7 @@ unsigned long`
`450`	`450`	`torture_random(struct torture_random_state *trsp)`
`451`	`451`	`{`
`452`	`452`	`if (--trsp->trs_count < 0) {`
`453`		`- trsp->trs_state += (unsigned long)local_clock();`
	`453`	`+ trsp->trs_state += (unsigned long)local_clock() + raw_smp_processor_id();`
`454`	`454`	`trsp->trs_count = TORTURE_RANDOM_REFRESH;`
`455`	`455`	`}`
`456`	`456`	`trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +`