From: Breno Leitao Date: Mon, 18 Nov 2024 11:15:17 +0000 (-0800) Subject: netpoll: Use rcu_access_pointer() in __netpoll_setup X-Git-Tag: v5.15.174~55 X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=8a4534483e02c885032cbb16f2c4b513ee1b84d4;p=thirdparty%2Fkernel%2Fstable.git netpoll: Use rcu_access_pointer() in __netpoll_setup [ Upstream commit c69c5e10adb903ae2438d4f9c16eccf43d1fcbc1 ] The ndev->npinfo pointer in __netpoll_setup() 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. Reviewed-by: Michal Kubiak Signed-off-by: Breno Leitao Link: https://patch.msgid.link/20241118-netpoll_rcu-v1-1-a1888dcb4a02@debian.org Signed-off-by: Jakub Kicinski Signed-off-by: Sasha Levin --- diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 2a9d95368d5a2..597e83e2bce86 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -636,7 +636,7 @@ int __netpoll_setup(struct netpoll *np, struct net_device *ndev) goto out; } - if (!ndev->npinfo) { + if (!rcu_access_pointer(ndev->npinfo)) { npinfo = kmalloc(sizeof(*npinfo), GFP_KERNEL); if (!npinfo) { err = -ENOMEM;