From:   Vernon Yang <vernon2gm@gmail.com>
To:     torvalds@linux-foundation.org, tytso@mit.edu, Jason@zx2c4.com,
        davem@davemloft.net, edumazet@google.com, kuba@kernel.org,
        pabeni@redhat.com, jejb@linux.ibm.com, martin.petersen@oracle.com,
        yury.norov@gmail.com, andriy.shevchenko@linux.intel.com,
        linux@rasmusvillemoes.dk, james.smart@broadcom.com,
        dick.kennedy@broadcom.com
Cc:     linux-kernel@vger.kernel.org, wireguard@lists.zx2c4.com,
        netdev@vger.kernel.org, linux-scsi@vger.kernel.org,
        Vernon Yang <vernon2gm@gmail.com>
Subject: [PATCH v2 2/4] wireguard: fix wg_cpumask_choose_online() if no further cpus set
Date:   Tue,  7 Mar 2023 04:47:21 +0800
Message-Id: <20230306204723.2584724-3-vernon2gm@gmail.com>
In-Reply-To: <20230306204723.2584724-1-vernon2gm@gmail.com>
References: <20230306204723.2584724-1-vernon2gm@gmail.com>
MIME-Version: 1.0
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Precedence: bulk

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 <vernon2gm@gmail.com>
---
 drivers/net/wireguard/queueing.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/net/wireguard/queueing.h b/drivers/net/wireguard/queueing.h
index 583adb37ee1e..125284b346a7 100644
--- a/drivers/net/wireguard/queueing.h
+++ b/drivers/net/wireguard/queueing.h
@@ -106,7 +106,7 @@ static inline int wg_cpumask_choose_online(int *stored_cpu, unsigned int id)
 {
 	unsigned int cpu = *stored_cpu, cpu_index, i;
 
-	if (unlikely(cpu == nr_cpumask_bits ||
+	if (unlikely(cpu >= nr_cpu_ids ||
 		     !cpumask_test_cpu(cpu, cpu_online_mask))) {
 		cpu_index = id % cpumask_weight(cpu_online_mask);
 		cpu = cpumask_first(cpu_online_mask);
-- 
2.34.1