Patch "pktgen: use cpus_read_lock() in pg_net_init()" has been added to the 6.10-stable tree

[Sasha Levin <sashal@xxxxxxxxxx>]

This is a note to let you know that I've just added the patch titled

    pktgen: use cpus_read_lock() in pg_net_init()

to the 6.10-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     pktgen-use-cpus_read_lock-in-pg_net_init.patch
and it can be found in the queue-6.10 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.



commit d747dfe13cdcad62a2e282585c4ade837b461a5b
Author: Eric Dumazet <edumazet@xxxxxxxxxx>
Date:   Wed Aug 21 17:53:39 2024 +0000

    pktgen: use cpus_read_lock() in pg_net_init()
    
    [ Upstream commit 979b581e4c69257acab1af415ddad6b2d78a2fa5 ]
    
    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@xxxxxxxxxx>
    Link: https://patch.msgid.link/20240821175339.1191779-1-edumazet@xxxxxxxxxx
    Signed-off-by: Jakub Kicinski <kuba@xxxxxxxxxx>
    Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>

diff --git a/net/core/pktgen.c b/net/core/pktgen.c
index ea55a758a475a..197a50ef8e2e1 100644
--- 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");