From: Breno Leitao leitao@debian.org
[ 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 michal.kubiak@intel.com Signed-off-by: Breno Leitao leitao@debian.org Link: https://patch.msgid.link/20241118-netpoll_rcu-v1-1-a1888dcb4a02@debian.org Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- net/core/netpoll.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/core/netpoll.c b/net/core/netpoll.c index f76afab9fd8bd..4475b2174bcc4 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -635,7 +635,7 @@ 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;