Re: [PATCH v2 mptcp-next 5/8] mptcp: faster active backup recovery

[kernel test robot <lkp@intel.com>]

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Hi Paolo,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on mptcp/export]
[also build test WARNING on kselftest/next linus/master v5.14-rc1 next-20210713]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Paolo-Abeni/mptcp-refactor-active-backup/20210714-051541
base:   https://github.com/multipath-tcp/mptcp_net-next.git export
config: x86_64-randconfig-r006-20210713 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 8d69635ed9ecf36fd0ca85906bfde17949671cbe)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # https://github.com/0day-ci/linux/commit/bc57ec20ec19b4d0b6de45ef1df8c8c3685c7fe2
        git remote add linux-review https://github.com/0day-ci/linux
        git fetch --no-tags linux-review Paolo-Abeni/mptcp-refactor-active-backup/20210714-051541
        git checkout bc57ec20ec19b4d0b6de45ef1df8c8c3685c7fe2
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/mptcp/pm_netlink.c:924:8: warning: variable 'push' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
                           if (!tcp_rtx_and_write_queues_empty(ssk)) {
                               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/mptcp/pm_netlink.c:931:8: note: uninitialized use occurs here
                           if (push)
                               ^~~~
   net/mptcp/pm_netlink.c:924:4: note: remove the 'if' if its condition is always true
                           if (!tcp_rtx_and_write_queues_empty(ssk)) {
                           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   net/mptcp/pm_netlink.c:911:17: note: initialize the variable 'push' to silence this warning
           bool slow, push;
                          ^
                           = 0
   1 warning generated.


vim +924 net/mptcp/pm_netlink.c

   903	
   904	void mptcp_pm_nl_subflow_chk_stale(const struct mptcp_sock *msk, struct sock *ssk)
   905	{
   906		struct mptcp_subflow_context *iter, *subflow = mptcp_subflow_ctx(ssk);
   907		struct sock *sk = (struct sock *)msk;
   908		unsigned int active_max_loss_cnt;
   909		struct net *net = sock_net(sk);
   910		unsigned int stale_loss_cnt;
   911		bool slow, push;
   912	
   913		stale_loss_cnt = mptcp_stale_loss_cnt(net);
   914		if (subflow->stale || !stale_loss_cnt || subflow->stale_count <= stale_loss_cnt)
   915			return;
   916	
   917		/* look for another available subflow not in loss state */
   918		active_max_loss_cnt = max_t(int, stale_loss_cnt - 1, 1);
   919		mptcp_for_each_subflow(msk, iter) {
   920			if (iter != subflow && mptcp_subflow_active(iter) &&
   921			    iter->stale_count < active_max_loss_cnt) {
   922				/* we have some alteratives, try to mark this subflow as idle ...*/
   923				slow = lock_sock_fast(ssk);
 > 924				if (!tcp_rtx_and_write_queues_empty(ssk)) {
   925					subflow->stale = 1;
   926					push = __mptcp_retransmit_pending_data(sk);
   927				}
   928				unlock_sock_fast(ssk, slow);
   929	
   930				/* pending data on the idle subflow: retransmit */
   931				if (push)
   932					__mptcp_push_pending(sk, 0);
   933				return;
   934			}
   935		}
   936	}
   937	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org

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