[PATCH net 2/2] netpoll: Use rcu_access_pointer() in netpoll_poll_lock

[Breno Leitao <leitao@debian.org>]

The ndev->npinfo pointer in netpoll_poll_lock() is RCU-protected but is
being accessed directly for a NULL check. While no RCU read lock is held
in this context, we should still use proper RCU primitives for
consistency and correctness.

Replace the direct NULL check with rcu_access_pointer(), which is the
appropriate primitive when only checking for NULL without dereferencing
the pointer. This function provides the necessary ordering guarantees
without requiring RCU read-side protection.

Signed-off-by: Breno Leitao <leitao@debian.org>
Fixes: bea3348eef27 ("[NET]: Make NAPI polling independent of struct net_device objects.")
---
 include/linux/netpoll.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/netpoll.h b/include/linux/netpoll.h
index cd4e28db0cbd77572a579aff2067b5864d1a904a..959a4daacea1f2f76536e309d198bc14407942a4 100644
--- a/include/linux/netpoll.h
+++ b/include/linux/netpoll.h
@@ -72,7 +72,7 @@ static inline void *netpoll_poll_lock(struct napi_struct *napi)
 {
 	struct net_device *dev = napi->dev;
 
-	if (dev && dev->npinfo) {
+	if (dev && rcu_access_pointer(dev->npinfo)) {
 		int owner = smp_processor_id();
 
 		while (cmpxchg(&napi->poll_owner, -1, owner) != -1)

-- 
2.43.5