Commit a57d5a72 authored by Breno Leitao's avatar Breno Leitao Committed by Jakub Kicinski
Browse files

netpoll: Use rcu_access_pointer() in netpoll_poll_lock 



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.

Fixes: bea3348e ("[NET]: Make NAPI polling independent of struct net_device objects.")
Signed-off-by: default avatarBreno Leitao <leitao@debian.org>
Reviewed-by: default avatarMichal Kubiak <michal.kubiak@intel.com>
Link: https://patch.msgid.link/20241118-netpoll_rcu-v1-2-a1888dcb4a02@debian.org


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c69c5e10

include/linux/netpoll.h

+1 −1
Original line number Diff line number Diff line
@@ -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)