pktgen: use cpus_read_lock() in pg_net_init()

I have seen the WARN_ON(smp_processor_id() != cpu) firing
in pktgen_thread_worker() during tests.

We must use cpus_read_lock()/cpus_read_unlock()
around the for_each_online_cpu(cpu) loop.

While we are at it use WARN_ON_ONCE() to avoid a possible syslog flood.

Fixes: 1da177e4c3f4 ("Linux-2.6.12-rc2")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://patch.msgid.link/20240821175339.1191779-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index ea55a758a475ab0ee22d9ac91f0ac9f0a6975e1f..197a50ef8e2e1bbe9f3906dfb80e80d913534b81 100644 (file)
--- a/net/core/pktgen.c
+++ b/net/core/pktgen.c
@@ -3654,7 +3654,7 @@ static int pktgen_thread_worker(void *arg)
        struct pktgen_dev *pkt_dev = NULL;
        int cpu = t->cpu;
 
-       WARN_ON(smp_processor_id() != cpu);
+       WARN_ON_ONCE(smp_processor_id() != cpu);
 
        init_waitqueue_head(&t->queue);
        complete(&t->start_done);
@@ -3989,6 +3989,7 @@ static int __net_init pg_net_init(struct net *net)
                goto remove;
        }
 
+       cpus_read_lock();
        for_each_online_cpu(cpu) {
                int err;
 
@@ -3997,6 +3998,7 @@ static int __net_init pg_net_init(struct net *net)
                        pr_warn("Cannot create thread for cpu %d (%d)\n",
                                   cpu, err);
        }
+       cpus_read_unlock();
 
        if (list_empty(&pn->pktgen_threads)) {
                pr_err("Initialization failed for all threads\n");