[PATCH v2 1/4] random: fix try_to_generate_entropy() if no further cpus set

[Vernon Yang]

When cpumask_next() the return value is greater than or equal to
nr_cpu_ids, it indicates invalid.

Before commit 596ff4a09b89 ("cpumask: re-introduce constant-sized cpumask
optimizations"), when cpumask_next() returned an invalid cpu, the driver
used the judgment equal to nr_cpu_ids to indicate the invalid cpu, so it
happened to work normally, but this is the wrong approach.

After commit 596ff4a09b89 ("cpumask: re-introduce constant-sized cpumask
optimizations"), these incorrect practices actively buggy, so fix it to
correctly.

Signed-off-by: Vernon Yang <vernon...@gmail.com>
---
 drivers/char/random.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/char/random.c b/drivers/char/random.c
index ce3ccd172cc8..253f2ddb8913 100644
--- a/drivers/char/random.c
+++ b/drivers/char/random.c
@@ -1311,7 +1311,7 @@ static void __cold try_to_generate_entropy(void)
                        /* Basic CPU round-robin, which avoids the current CPU. 
*/
                        do {
                                cpu = cpumask_next(cpu, &timer_cpus);
-                               if (cpu == nr_cpumask_bits)
+                               if (cpu >= nr_cpu_ids)
                                        cpu = cpumask_first(&timer_cpus);
                        } while (cpu == smp_processor_id() && num_cpus > 1);
 
-- 
2.34.1