[tip:x86/sgx 2/2] arch/x86/kernel/cpu/sgx/main.c:496:7: warning: variable 'nid' is used uninitialized whenever 'if' condition is false

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

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tree:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git x86/sgx
head:   5b8719504e3adf47646273781591ad439b3c3c7a
commit: 5b8719504e3adf47646273781591ad439b3c3c7a [2/2] x86/sgx: Add a basic NUMA allocation scheme to sgx_alloc_epc_page()
config: x86_64-randconfig-r004-20210318 (attached as .config)
compiler: clang version 13.0.0 (https://github.com/llvm/llvm-project 6db3ab2903f42712f44000afb5aa467efbd25f35)
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://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git/commit/?id=5b8719504e3adf47646273781591ad439b3c3c7a
        git remote add tip https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git
        git fetch --no-tags tip x86/sgx
        git checkout 5b8719504e3adf47646273781591ad439b3c3c7a
        # 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 >>):

>> arch/x86/kernel/cpu/sgx/main.c:496:7: warning: variable 'nid' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
                   if (page)
                       ^~~~
   arch/x86/kernel/cpu/sgx/main.c:502:22: note: uninitialized use occurs here
                   nid = next_node_in(nid, sgx_numa_mask);
                                      ^~~
   include/linux/nodemask.h:278:46: note: expanded from macro 'next_node_in'
   #define next_node_in(n, src) __next_node_in((n), &(src))
                                                ^
   arch/x86/kernel/cpu/sgx/main.c:496:3: note: remove the 'if' if its condition is always true
                   if (page)
                   ^~~~~~~~~
   arch/x86/kernel/cpu/sgx/main.c:494:6: warning: variable 'nid' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
           if (node_isset(nid_of_current, sgx_numa_mask)) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   include/linux/nodemask.h:152:36: note: expanded from macro 'node_isset'
   #define node_isset(node, nodemask) test_bit((node), (nodemask).bits)
                                      ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/x86/kernel/cpu/sgx/main.c:502:22: note: uninitialized use occurs here
                   nid = next_node_in(nid, sgx_numa_mask);
                                      ^~~
   include/linux/nodemask.h:278:46: note: expanded from macro 'next_node_in'
   #define next_node_in(n, src) __next_node_in((n), &(src))
                                                ^
   arch/x86/kernel/cpu/sgx/main.c:494:2: note: remove the 'if' if its condition is always true
           if (node_isset(nid_of_current, sgx_numa_mask)) {
           ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   arch/x86/kernel/cpu/sgx/main.c:492:9: note: initialize the variable 'nid' to silence this warning
           int nid;
                  ^
                   = 0
   2 warnings generated.


vim +496 arch/x86/kernel/cpu/sgx/main.c

d2285493bef310 Jarkko Sakkinen 2020-11-13  477  
d2285493bef310 Jarkko Sakkinen 2020-11-13  478  /**
d2285493bef310 Jarkko Sakkinen 2020-11-13  479   * __sgx_alloc_epc_page() - Allocate an EPC page
d2285493bef310 Jarkko Sakkinen 2020-11-13  480   *
5b8719504e3adf Jarkko Sakkinen 2021-03-18  481   * Iterate through NUMA nodes and reserve ia free EPC page to the caller. Start
5b8719504e3adf Jarkko Sakkinen 2021-03-18  482   * from the NUMA node, where the caller is executing.
d2285493bef310 Jarkko Sakkinen 2020-11-13  483   *
d2285493bef310 Jarkko Sakkinen 2020-11-13  484   * Return:
5b8719504e3adf Jarkko Sakkinen 2021-03-18  485   * - an EPC page:	A borrowed EPC pages were available.
5b8719504e3adf Jarkko Sakkinen 2021-03-18  486   * - NULL:		Out of EPC pages.
d2285493bef310 Jarkko Sakkinen 2020-11-13  487   */
d2285493bef310 Jarkko Sakkinen 2020-11-13  488  struct sgx_epc_page *__sgx_alloc_epc_page(void)
d2285493bef310 Jarkko Sakkinen 2020-11-13  489  {
d2285493bef310 Jarkko Sakkinen 2020-11-13  490  	struct sgx_epc_page *page;
5b8719504e3adf Jarkko Sakkinen 2021-03-18  491  	int nid_of_current = numa_node_id();
5b8719504e3adf Jarkko Sakkinen 2021-03-18  492  	int nid;
d2285493bef310 Jarkko Sakkinen 2020-11-13  493  
5b8719504e3adf Jarkko Sakkinen 2021-03-18  494  	if (node_isset(nid_of_current, sgx_numa_mask)) {
5b8719504e3adf Jarkko Sakkinen 2021-03-18  495  		page = __sgx_alloc_epc_page_from_node(nid_of_current);
d2285493bef310 Jarkko Sakkinen 2020-11-13 @496  		if (page)
d2285493bef310 Jarkko Sakkinen 2020-11-13  497  			return page;
d2285493bef310 Jarkko Sakkinen 2020-11-13  498  	}
d2285493bef310 Jarkko Sakkinen 2020-11-13  499  
5b8719504e3adf Jarkko Sakkinen 2021-03-18  500  	/* Fall back to the non-local NUMA nodes: */
5b8719504e3adf Jarkko Sakkinen 2021-03-18  501  	while (true) {
5b8719504e3adf Jarkko Sakkinen 2021-03-18  502  		nid = next_node_in(nid, sgx_numa_mask);
5b8719504e3adf Jarkko Sakkinen 2021-03-18  503  		if (nid == nid_of_current)
5b8719504e3adf Jarkko Sakkinen 2021-03-18  504  			break;
5b8719504e3adf Jarkko Sakkinen 2021-03-18  505  
5b8719504e3adf Jarkko Sakkinen 2021-03-18  506  		page = __sgx_alloc_epc_page_from_node(nid);
5b8719504e3adf Jarkko Sakkinen 2021-03-18  507  		if (page)
5b8719504e3adf Jarkko Sakkinen 2021-03-18  508  			break;
5b8719504e3adf Jarkko Sakkinen 2021-03-18  509  	}
5b8719504e3adf Jarkko Sakkinen 2021-03-18  510  
5b8719504e3adf Jarkko Sakkinen 2021-03-18  511  	return page;
d2285493bef310 Jarkko Sakkinen 2020-11-13  512  }
d2285493bef310 Jarkko Sakkinen 2020-11-13  513  

:::::: The code at line 496 was first introduced by commit
:::::: d2285493bef310b66b56dfe4eb75c1e2f431ea5c x86/sgx: Add SGX page allocator functions

:::::: TO: Jarkko Sakkinen <jarkko@kernel.org>
:::::: CC: Borislav Petkov <bp@suse.de>

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

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