| Message ID | 20241021183239.79741-2-kuniyu@amazon.com (mailing list archive) |
|---|---|
| State | Accepted |
| Commit | 9cb7e40d388d6c0e4677809c6b2950bc67fd8830 |
| Delegated to: | Netdev Maintainers |
| Headers | show |
| Series | ipv4: Convert RTM_{NEW,DEL}ADDR and more to per-netns RTNL. | expand |
On Mon, Oct 21, 2024 at 11:32:28AM -0700, Kuniyuki Iwashima wrote: > When CONFIG_DEBUG_NET_SMALL_RTNL is off, rtnl_net_dereference() is the > static inline wrapper of rtnl_dereference() returning a plain (void *) > pointer to make sure net is always evaluated as requested in [0]. > > But, it makes sparse complain [1] when the pointer has __rcu annotation: > > net/ipv4/devinet.c:674:47: sparse: warning: incorrect type in argument 2 (different address spaces) > net/ipv4/devinet.c:674:47: sparse: expected void *p > net/ipv4/devinet.c:674:47: sparse: got struct in_ifaddr [noderef] __rcu * > > Also, if we evaluate net as (void *) in a macro, then the compiler > in turn fails to build due to -Werror=unused-value. > > #define rtnl_net_dereference(net, p) \ > ({ \ > (void *)net; \ > rtnl_dereference(p); \ > }) > > net/ipv4/devinet.c: In function ‘inet_rtm_deladdr’: > ./include/linux/rtnetlink.h:154:17: error: statement with no effect [-Werror=unused-value] > 154 | (void *)net; \ > net/ipv4/devinet.c:674:21: note: in expansion of macro ‘rtnl_net_dereference’ > 674 | (ifa = rtnl_net_dereference(net, *ifap)) != NULL; > | ^~~~~~~~~~~~~~~~~~~~ > > Let's go back to the original simplest macro. > > Note that checkpatch complains about this approach, but it's one-shot and > less noisy than the other two. > > WARNING: Argument 'net' is not used in function-like macro > #76: FILE: include/linux/rtnetlink.h:142: > +#define rtnl_net_dereference(net, p) \ > + rtnl_dereference(p) > > Fixes: 844e5e7e656d ("rtnetlink: Add assertion helpers for per-netns RTNL.") > Link: https://lore.kernel.org/netdev/20241004132145.7fd208e9@kernel.org/ [0] > Reported-by: kernel test robot <lkp@intel.com> > Closes: https://lore.kernel.org/oe-kbuild-all/202410200325.SaEJmyZS-lkp@intel.com/ [1] > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Thanks, I was able to reproduce the build problem as described. Reviewed-by: Simon Horman <horms@kernel.org>
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h index 8468a4ce8510..0e62918de63b 100644 --- a/include/linux/rtnetlink.h +++ b/include/linux/rtnetlink.h @@ -137,21 +137,12 @@ static inline void ASSERT_RTNL_NET(struct net *net) ASSERT_RTNL(); } -static inline void *rcu_dereference_rtnl_net(struct net *net, void *p) -{ - return rcu_dereference_rtnl(p); -} - -static inline void *rtnl_net_dereference(struct net *net, void *p) -{ - return rtnl_dereference(p); -} - -static inline void *rcu_replace_pointer_rtnl_net(struct net *net, - void *rp, void *p) -{ - return rcu_replace_pointer_rtnl(rp, p); -} +#define rcu_dereference_rtnl_net(net, p) \ + rcu_dereference_rtnl(p) +#define rtnl_net_dereference(net, p) \ + rtnl_dereference(p) +#define rcu_replace_pointer_rtnl_net(net, rp, p) \ + rcu_replace_pointer_rtnl(rp, p) #endif static inline struct netdev_queue *dev_ingress_queue(struct net_device *dev)
When CONFIG_DEBUG_NET_SMALL_RTNL is off, rtnl_net_dereference() is the static inline wrapper of rtnl_dereference() returning a plain (void *) pointer to make sure net is always evaluated as requested in [0]. But, it makes sparse complain [1] when the pointer has __rcu annotation: net/ipv4/devinet.c:674:47: sparse: warning: incorrect type in argument 2 (different address spaces) net/ipv4/devinet.c:674:47: sparse: expected void *p net/ipv4/devinet.c:674:47: sparse: got struct in_ifaddr [noderef] __rcu * Also, if we evaluate net as (void *) in a macro, then the compiler in turn fails to build due to -Werror=unused-value. #define rtnl_net_dereference(net, p) \ ({ \ (void *)net; \ rtnl_dereference(p); \ }) net/ipv4/devinet.c: In function ‘inet_rtm_deladdr’: ./include/linux/rtnetlink.h:154:17: error: statement with no effect [-Werror=unused-value] 154 | (void *)net; \ net/ipv4/devinet.c:674:21: note: in expansion of macro ‘rtnl_net_dereference’ 674 | (ifa = rtnl_net_dereference(net, *ifap)) != NULL; | ^~~~~~~~~~~~~~~~~~~~ Let's go back to the original simplest macro. Note that checkpatch complains about this approach, but it's one-shot and less noisy than the other two. WARNING: Argument 'net' is not used in function-like macro #76: FILE: include/linux/rtnetlink.h:142: +#define rtnl_net_dereference(net, p) \ + rtnl_dereference(p) Fixes: 844e5e7e656d ("rtnetlink: Add assertion helpers for per-netns RTNL.") Link: https://lore.kernel.org/netdev/20241004132145.7fd208e9@kernel.org/ [0] Reported-by: kernel test robot <lkp@intel.com> Closes: https://lore.kernel.org/oe-kbuild-all/202410200325.SaEJmyZS-lkp@intel.com/ [1] Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> --- include/linux/rtnetlink.h | 21 ++++++--------------- 1 file changed, 6 insertions(+), 15 deletions(-)