net/ipv4/tcp_cong.c:238:22: sparse: sparse: incorrect type in assignment (different address spaces)

[kernel test robot]

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   6bfb56e93bcef41859c2d5ab234ffd80b691be35
commit: e188f3330a13df904d77003846eafd3edf99009d ARC: cmpxchg/xchg: rewrite as macros to make type safe
date:   10 months ago
config: arc-randconfig-s032-20220530 (https://download.01.org/0day-ci/archive/20220609/202206091138.G3gUfGes-lkp@xxxxxxxxx/config)
compiler: arceb-elf-gcc (GCC) 11.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # apt-get install sparse
        # sparse version: v0.6.4-26-gb3cf30ba-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=e188f3330a13df904d77003846eafd3edf99009d
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout e188f3330a13df904d77003846eafd3edf99009d
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.3.0 make.cross C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' O=build_dir ARCH=arc SHELL=/bin/bash net/ipv4/

If you fix the issue, kindly add following tag where applicable
Reported-by: kernel test robot <lkp@xxxxxxxxx>


sparse warnings: (new ones prefixed by >>)
   net/ipv4/tcp_cong.c:238:24: sparse: sparse: incorrect type in initializer (different address spaces) @@     expected struct tcp_congestion_ops const [noderef] __rcu *_val_ @@     got struct tcp_congestion_ops *[assigned] ca @@
   net/ipv4/tcp_cong.c:238:24: sparse:     expected struct tcp_congestion_ops const [noderef] __rcu *_val_
   net/ipv4/tcp_cong.c:238:24: sparse:     got struct tcp_congestion_ops *[assigned] ca
>> net/ipv4/tcp_cong.c:238:22: sparse: sparse: incorrect type in assignment (different address spaces) @@     expected struct tcp_congestion_ops const *prev @@     got struct tcp_congestion_ops const [noderef] __rcu *[assigned] _val_ @@
   net/ipv4/tcp_cong.c:238:22: sparse:     expected struct tcp_congestion_ops const *prev
   net/ipv4/tcp_cong.c:238:22: sparse:     got struct tcp_congestion_ops const [noderef] __rcu *[assigned] _val_

vim +238 net/ipv4/tcp_cong.c

317a76f9a44b43 Stephen Hemminger 2005-06-23  219  
317a76f9a44b43 Stephen Hemminger 2005-06-23  220  /* Used by sysctl to change default congestion control */
6670e152447732 Stephen Hemminger 2017-11-14  221  int tcp_set_default_congestion_control(struct net *net, const char *name)
317a76f9a44b43 Stephen Hemminger 2005-06-23  222  {
317a76f9a44b43 Stephen Hemminger 2005-06-23  223  	struct tcp_congestion_ops *ca;
6670e152447732 Stephen Hemminger 2017-11-14  224  	const struct tcp_congestion_ops *prev;
6670e152447732 Stephen Hemminger 2017-11-14  225  	int ret;
317a76f9a44b43 Stephen Hemminger 2005-06-23  226  
6670e152447732 Stephen Hemminger 2017-11-14  227  	rcu_read_lock();
6670e152447732 Stephen Hemminger 2017-11-14  228  	ca = tcp_ca_find_autoload(net, name);
6670e152447732 Stephen Hemminger 2017-11-14  229  	if (!ca) {
6670e152447732 Stephen Hemminger 2017-11-14  230  		ret = -ENOENT;
0baf26b0fcd74b Martin KaFai Lau  2020-01-08  231  	} else if (!bpf_try_module_get(ca, ca->owner)) {
6670e152447732 Stephen Hemminger 2017-11-14  232  		ret = -EBUSY;
8d432592f30fcc Jonathon Reinhart 2021-05-01  233  	} else if (!net_eq(net, &init_net) &&
8d432592f30fcc Jonathon Reinhart 2021-05-01  234  			!(ca->flags & TCP_CONG_NON_RESTRICTED)) {
8d432592f30fcc Jonathon Reinhart 2021-05-01  235  		/* Only init netns can set default to a restricted algorithm */
8d432592f30fcc Jonathon Reinhart 2021-05-01  236  		ret = -EPERM;
6670e152447732 Stephen Hemminger 2017-11-14  237  	} else {
6670e152447732 Stephen Hemminger 2017-11-14 @238  		prev = xchg(&net->ipv4.tcp_congestion_control, ca);
6670e152447732 Stephen Hemminger 2017-11-14  239  		if (prev)
0baf26b0fcd74b Martin KaFai Lau  2020-01-08  240  			bpf_module_put(prev, prev->owner);
317a76f9a44b43 Stephen Hemminger 2005-06-23  241  
6670e152447732 Stephen Hemminger 2017-11-14  242  		ca->flags |= TCP_CONG_NON_RESTRICTED;
317a76f9a44b43 Stephen Hemminger 2005-06-23  243  		ret = 0;
317a76f9a44b43 Stephen Hemminger 2005-06-23  244  	}
6670e152447732 Stephen Hemminger 2017-11-14  245  	rcu_read_unlock();
317a76f9a44b43 Stephen Hemminger 2005-06-23  246  
317a76f9a44b43 Stephen Hemminger 2005-06-23  247  	return ret;
317a76f9a44b43 Stephen Hemminger 2005-06-23  248  }
317a76f9a44b43 Stephen Hemminger 2005-06-23  249  

:::::: The code at line 238 was first introduced by commit
:::::: 6670e152447732ba90626f36dfc015a13fbf150e tcp: Namespace-ify sysctl_tcp_default_congestion_control

:::::: TO: Stephen Hemminger <stephen@xxxxxxxxxxxxxxxxxx>
:::::: CC: David S. Miller <davem@xxxxxxxxxxxxx>

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