netpoll: Use rcu_access_pointer() in __netpoll_setup

BugLink: https://bugs.launchpad.net/bugs/2102118

[ 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>
Signed-off-by: Koichiro Den <koichiro.den@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

This commit is contained in:

Breno Leitao

2025-03-12 22:51:00 +09:00

committed by

Stefan Bader

parent 9e3209308d

commit 2071c7c3da

1 changed files with 1 additions and 1 deletions

									
										net/core/netpoll.c
									
		+1
		-1
	
												View File
												
				@@ -633,7 +633,7 @@ 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;