Re: include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar

[Philip Li <philip.li@intel.com>]

On Sat, Jan 10, 2026 at 10:15:08PM +0000, Al Viro wrote:
> On Sun, Jan 11, 2026 at 05:06:31AM +0800, kernel test robot wrote:
> 
> Folks, could your bot be taught to recognize that kind of situation?

Got it, we will follow up to update the bot logic to ignore further
reports for this pattern.

> It's very clear what's going on - an inline function that gets the
> same warning with this config every time it is called.  Commit in
> question has added several calls of that thing; the origin of warning
> has nothing whatsoever to do with it, and that can be guessed without
> even looking at the source - the quoted diff between the logs is quite
> enough for that.
> 
> Looking at the function in question,
> 
> > sparse warnings: (new ones prefixed by >>)
> >    net/ipv4/datagram.c: note: in included file (through include/net/inet_sock.h, include/net/ip.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/raw.c: note: in included file (through include/linux/mroute_base.h, include/linux/mroute.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/inet_connection_sock.c:328:36: sparse: sparse: context imbalance in 'inet_csk_find_open_port' - wrong count at exit
> >    net/ipv4/inet_connection_sock.c:605:23: sparse: sparse: context imbalance in 'inet_csk_get_port' - unexpected unlock
> >    net/ipv4/inet_connection_sock.c: note: in included file (through include/net/inet_sock.h, include/net/inet_connection_sock.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> >    net/ipv4/inet_connection_sock.c:1467:9: sparse: sparse: context imbalance in 'inet_csk_complete_hashdance' - unexpected unlock
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/route.c: note: in included file (through include/linux/mroute_base.h, include/linux/mroute.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/ip_output.c: note: in included file (through include/net/inet_sock.h, include/net/ip.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/af_inet.c: note: in included file (through include/net/inet_sock.h, include/net/ip.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/tcp_ipv4.c:3415:41: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const *data @@     got struct tcp_congestion_ops const [noderef] __rcu *tcp_congestion_control @@
> >    net/ipv4/tcp_ipv4.c:3415:41: sparse:     expected void const *data
> >    net/ipv4/tcp_ipv4.c:3415:41: sparse:     got struct tcp_congestion_ops const [noderef] __rcu *tcp_congestion_control
> >    net/ipv4/tcp_ipv4.c:3537:45: sparse: sparse: incorrect type in argument 1 (different address spaces) @@     expected void const *data @@     got struct tcp_congestion_ops const [noderef] __rcu *extern [addressable] [toplevel] tcp_congestion_control @@
> >    net/ipv4/tcp_ipv4.c:3537:45: sparse:     expected void const *data
> >    net/ipv4/tcp_ipv4.c:3537:45: sparse:     got struct tcp_congestion_ops const [noderef] __rcu *extern [addressable] [toplevel] tcp_congestion_control
> >    net/ipv4/tcp_ipv4.c:3541:50: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected struct tcp_congestion_ops const [noderef] __rcu *tcp_congestion_control @@     got struct tcp_congestion_ops * @@
> >    net/ipv4/tcp_ipv4.c:3541:50: sparse:     expected struct tcp_congestion_ops const [noderef] __rcu *tcp_congestion_control
> >    net/ipv4/tcp_ipv4.c:3541:50: sparse:     got struct tcp_congestion_ops *
> >    net/ipv4/tcp_ipv4.c: note: in included file (through include/net/inet_sock.h, include/net/icmp.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> >    net/ipv4/tcp_ipv4.c:1846:25: sparse: sparse: context imbalance in 'tcp_v4_syn_recv_sock' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:2139:17: sparse: sparse: context imbalance in 'tcp_add_backlog' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:2401:21: sparse: sparse: context imbalance in 'tcp_v4_rcv' - different lock contexts for basic block
> >    net/ipv4/tcp_ipv4.c:2612:13: sparse: sparse: context imbalance in 'listening_get_first' - wrong count at exit
> >    net/ipv4/tcp_ipv4.c:2660:29: sparse: sparse: context imbalance in 'listening_get_next' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:2693:13: sparse: sparse: context imbalance in 'established_get_first' - wrong count at exit
> >    net/ipv4/tcp_ipv4.c:2738:40: sparse: sparse: context imbalance in 'established_get_next' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:2870:36: sparse: sparse: context imbalance in 'tcp_seq_stop' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:3091:20: sparse: sparse: context imbalance in 'bpf_iter_tcp_listening_batch' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:3119:40: sparse: sparse: context imbalance in 'bpf_iter_tcp_established_batch' - unexpected unlock
> >    net/ipv4/tcp_ipv4.c:3416:41: sparse: sparse: dereference of noderef expression
> >    net/ipv4/tcp_ipv4.c:3416:41: sparse: sparse: dereference of noderef expression
> >    net/ipv4/tcp_ipv4.c:3538:45: sparse: sparse: dereference of noderef expression
> >    net/ipv4/tcp_ipv4.c:3538:45: sparse: sparse: dereference of noderef expression
> > --
> >    net/ipv4/ping.c: note: in included file (through include/net/inet_sock.h, include/net/ip.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> > --
> >    net/ipv4/udp.c: note: in included file (through include/linux/bpf-cgroup.h):
> > >> include/net/sock.h:2100:16: sparse: sparse: cast to non-scalar
> >    include/net/sock.h:2100:16: sparse: sparse: cast from non-scalar
> >    net/ipv4/udp.c:1668:28: sparse: sparse: context imbalance in 'udp_rmem_release' - unexpected unlock
> >    net/ipv4/udp.c:1700:19: sparse: sparse: context imbalance in 'busylock_acquire' - wrong count at exit
> >    net/ipv4/udp.c:1712:28: sparse: sparse: context imbalance in 'busylock_release' - unexpected unlock
> >    net/ipv4/udp.c:3305:9: sparse: sparse: context imbalance in 'udp_get_first' - wrong count at exit
> >    net/ipv4/udp.c:3322:39: sparse: sparse: context imbalance in 'udp_get_next' - unexpected unlock
> >    net/ipv4/udp.c:3370:31: sparse: sparse: context imbalance in 'udp_seq_stop' - unexpected unlock
> > 
> > vim +2100 include/net/sock.h
> > 
> >   2096	
> >   2097	static inline kuid_t sk_uid(const struct sock *sk)
> >   2098	{
> >   2099		/* Paired with WRITE_ONCE() in sockfs_setattr() */
> > > 2100		return READ_ONCE(sk->sk_uid);
> >   2101	}
> >   2102	
> > 
> > -- 
> > 0-DAY CI Kernel Test Service
> > https://github.com/intel/lkp-tests/wiki
> > 
>