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From: kernel test robot <lkp@intel.com>
To: kbuild@lists.01.org
Subject: [ast-bpf:relo_core 5/11] kernel/bpf/btf.c:6524:2: warning: Value stored to 'err' is never read [clang-analyzer-deadcode.DeadStores]
Date: Sun, 19 Sep 2021 17:44:02 +0800	[thread overview]
Message-ID: <202109191754.t1cndP9Q-lkp@intel.com> (raw)

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CC: llvm(a)lists.linux.dev
CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: Alexei Starovoitov <ast@kernel.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git relo_core
head:   35a0182c26565e1db43f99a764834bff8a2e4202
commit: 98beca424883749fbcf9f244bb26c96ed3102502 [5/11] bpf: Add bpf_core_add_cands() and wire it into bpf_core_apply_relo_insn().
:::::: branch date: 2 days ago
:::::: commit date: 2 days ago
config: riscv-randconfig-c006-20210919 (attached as .config)
compiler: clang version 14.0.0 (https://github.com/llvm/llvm-project c8b3d7d6d6de37af68b2f379d0e37304f78e115f)
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 riscv cross compiling tool for clang build
        # apt-get install binutils-riscv64-linux-gnu
        # https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git/commit/?id=98beca424883749fbcf9f244bb26c96ed3102502
        git remote add ast-bpf https://git.kernel.org/pub/scm/linux/kernel/git/ast/bpf.git
        git fetch --no-tags ast-bpf relo_core
        git checkout 98beca424883749fbcf9f244bb26c96ed3102502
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=riscv clang-analyzer 

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


clang-analyzer warnings: (new ones prefixed by >>)
   kernel/sysctl.c:1578:4: note: Taking false branch
                           if (err)
                           ^
   kernel/sysctl.c:1580:8: note: Assuming 'val_a' is < 'bitmap_len'
                           if (val_a >= bitmap_len || neg) {
                               ^~~~~~~~~~~~~~~~~~~
   kernel/sysctl.c:1580:8: note: Left side of '||' is false
   kernel/sysctl.c:1580:31: note: 'neg' is false
                           if (val_a >= bitmap_len || neg) {
                                                      ^~~
   kernel/sysctl.c:1580:4: note: Taking false branch
                           if (val_a >= bitmap_len || neg) {
                           ^
   kernel/sysctl.c:1586:8: note: Assuming 'left' is 0
                           if (left) {
                               ^~~~
   kernel/sysctl.c:1586:4: note: Taking false branch
                           if (left) {
                           ^
   kernel/sysctl.c:1591:10: note: The left operand of '==' is a garbage value
                           if (c == '-') {
                               ~ ^
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   2 warnings generated.
   Suppressed 2 warnings (2 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   2 warnings generated.
   Suppressed 2 warnings (2 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (2 in non-user code, 8 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   Suppressed 10 warnings (3 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   2 warnings generated.
   Suppressed 2 warnings (2 in non-user code).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   12 warnings generated.
   kernel/bpf/btf.c:838:25: warning: Value stored to 't' during its initialization is never read [clang-analyzer-deadcode.DeadStores]
           const struct btf_type *t = show->state.type;
                                  ^   ~~~~~~~~~~~~~~~~
   kernel/bpf/btf.c:838:25: note: Value stored to 't' during its initialization is never read
           const struct btf_type *t = show->state.type;
                                  ^   ~~~~~~~~~~~~~~~~
>> kernel/bpf/btf.c:6524:2: warning: Value stored to 'err' is never read [clang-analyzer-deadcode.DeadStores]
           err = bpf_core_apply_relo_insn("prog_name", insn, 0, &core_relo, 0, btf, cands);
           ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/btf.c:6524:2: note: Value stored to 'err' is never read
           err = bpf_core_apply_relo_insn("prog_name", insn, 0, &core_relo, 0, btf, cands);
           ^     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   Suppressed 10 warnings (2 in non-user code, 8 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   10 warnings generated.
   include/linux/log2.h:57:13: warning: The result of the left shift is undefined due to shifting by '64', which is greater or equal to the width of type 'unsigned long' [clang-analyzer-core.UndefinedBinaryOperatorResult]
           return 1UL << fls_long(n - 1);
                      ^
   kernel/bpf/devmap.c:162:6: note: Assuming the condition is false
           if (!capable(CAP_NET_ADMIN))
               ^~~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:162:2: note: Taking false branch
           if (!capable(CAP_NET_ADMIN))
           ^
   kernel/bpf/devmap.c:166:6: note: Assuming 'dtab' is non-null
           if (!dtab)
               ^~~~~
   kernel/bpf/devmap.c:166:2: note: Taking false branch
           if (!dtab)
           ^
   kernel/bpf/devmap.c:169:8: note: Calling 'dev_map_init_map'
           err = dev_map_init_map(dtab, attr);
                 ^~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:118:6: note: Assuming field 'max_entries' is not equal to 0
           if (attr->max_entries == 0 || attr->key_size != 4 ||
               ^~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:118:6: note: Left side of '||' is false
   kernel/bpf/devmap.c:118:32: note: Assuming field 'key_size' is equal to 4
           if (attr->max_entries == 0 || attr->key_size != 4 ||
                                         ^~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:118:6: note: Left side of '||' is false
           if (attr->max_entries == 0 || attr->key_size != 4 ||
               ^
   kernel/bpf/devmap.c:119:7: note: Assuming the condition is false
               (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
                ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:119:62: note: Left side of '&&' is false
               (valsize != offsetofend(struct bpf_devmap_val, ifindex) &&
                                                                       ^
   kernel/bpf/devmap.c:121:6: note: Assuming the condition is false
               attr->map_flags & ~DEV_CREATE_FLAG_MASK)
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:118:2: note: Taking false branch
           if (attr->max_entries == 0 || attr->key_size != 4 ||
           ^
   kernel/bpf/devmap.c:132:6: note: Assuming field 'map_type' is equal to BPF_MAP_TYPE_DEVMAP_HASH
           if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
               ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
   kernel/bpf/devmap.c:132:2: note: Taking true branch
           if (attr->map_type == BPF_MAP_TYPE_DEVMAP_HASH) {
           ^
   kernel/bpf/devmap.c:133:21: note: '?' condition is false
                   dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
                                     ^
   include/linux/log2.h:176:2: note: expanded from macro 'roundup_pow_of_two'
           __builtin_constant_p(n) ? (             \
           ^
   kernel/bpf/devmap.c:133:21: note: Calling '__roundup_pow_of_two'
                   dtab->n_buckets = roundup_pow_of_two(dtab->map.max_entries);
                                     ^
   include/linux/log2.h:180:2: note: expanded from macro 'roundup_pow_of_two'
           __roundup_pow_of_two(n)                 \
           ^~~~~~~~~~~~~~~~~~~~~~~
   include/linux/log2.h:57:16: note: Calling 'fls_long'
           return 1UL << fls_long(n - 1);
                         ^~~~~~~~~~~~~~~
   include/linux/bitops.h:188:2: note: Taking false branch
           if (sizeof(l) == 4)
           ^
   include/linux/bitops.h:190:9: note: Calling 'fls64'
           return fls64(l);
                  ^~~~~~~~
   include/asm-generic/bitops/fls64.h:29:6: note: Assuming 'x' is not equal to 0
           if (x == 0)
               ^~~~~~
   include/asm-generic/bitops/fls64.h:29:2: note: Taking false branch
           if (x == 0)
           ^
   include/asm-generic/bitops/fls64.h:31:2: note: Returning the value 64
           return __fls(x) + 1;
           ^~~~~~~~~~~~~~~~~~~
   include/linux/bitops.h:190:9: note: Returning from 'fls64'
           return fls64(l);
                  ^~~~~~~~
   include/linux/bitops.h:190:2: note: Returning the value 64
           return fls64(l);
           ^~~~~~~~~~~~~~~
   include/linux/log2.h:57:16: note: Returning from 'fls_long'
           return 1UL << fls_long(n - 1);
                         ^~~~~~~~~~~~~~~
   include/linux/log2.h:57:13: note: The result of the left shift is undefined due to shifting by '64', which is greater or equal to the width of type 'unsigned long'
           return 1UL << fls_long(n - 1);
                      ^  ~~~~~~~~~~~~~~~
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).
   Use -header-filter=.* to display errors from all non-system headers. Use -system-headers to display errors from system headers as well.
   9 warnings generated.
   Suppressed 9 warnings (2 in non-user code, 7 with check filters).

vim +/err +6524 kernel/bpf/btf.c

98beca42488374 Alexei Starovoitov 2021-09-16  6491  
fab12a1832b619 Alexei Starovoitov 2021-09-08  6492  BPF_CALL_5(bpf_core_apply_relo, int, btf_fd, struct bpf_core_relo_desc *, relo,
fab12a1832b619 Alexei Starovoitov 2021-09-08  6493  	   int, relo_sz, void *, insn, int, flags)
fab12a1832b619 Alexei Starovoitov 2021-09-08  6494  {
98beca42488374 Alexei Starovoitov 2021-09-16  6495  	struct bpf_core_cand_list *cands = NULL;
98beca42488374 Alexei Starovoitov 2021-09-16  6496  	struct bpf_core_relo core_relo = {};
fab12a1832b619 Alexei Starovoitov 2021-09-08  6497  	struct btf *btf;
98beca42488374 Alexei Starovoitov 2021-09-16  6498  	int err;
fab12a1832b619 Alexei Starovoitov 2021-09-08  6499  
fab12a1832b619 Alexei Starovoitov 2021-09-08  6500  	if (flags)
fab12a1832b619 Alexei Starovoitov 2021-09-08  6501  		return -EINVAL;
98beca42488374 Alexei Starovoitov 2021-09-16  6502  
98beca42488374 Alexei Starovoitov 2021-09-16  6503  	if (sizeof(*relo) != relo_sz)
98beca42488374 Alexei Starovoitov 2021-09-16  6504  		return -EINVAL;
98beca42488374 Alexei Starovoitov 2021-09-16  6505  	btf = btf_get_by_fd(btf_fd);
98beca42488374 Alexei Starovoitov 2021-09-16  6506  	if (IS_ERR(btf))
98beca42488374 Alexei Starovoitov 2021-09-16  6507  		return PTR_ERR(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6508  	if (btf_is_kernel(btf)) {
98beca42488374 Alexei Starovoitov 2021-09-16  6509  		btf_put(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6510  		return -EACCES;
98beca42488374 Alexei Starovoitov 2021-09-16  6511  	}
98beca42488374 Alexei Starovoitov 2021-09-16  6512  	if (relo->kind != BPF_CORE_TYPE_ID_LOCAL) {
98beca42488374 Alexei Starovoitov 2021-09-16  6513  		cands = bpf_core_find_cands(btf, relo->type_id);
98beca42488374 Alexei Starovoitov 2021-09-16  6514  		if (IS_ERR(cands)) {
98beca42488374 Alexei Starovoitov 2021-09-16  6515  			btf_put(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6516  			printk("target candidate search failed for %d\n",
98beca42488374 Alexei Starovoitov 2021-09-16  6517  			       relo->type_id);
98beca42488374 Alexei Starovoitov 2021-09-16  6518                          return PTR_ERR(cands);
98beca42488374 Alexei Starovoitov 2021-09-16  6519                  }
98beca42488374 Alexei Starovoitov 2021-09-16  6520  	}
98beca42488374 Alexei Starovoitov 2021-09-16  6521  	core_relo.type_id = relo->type_id;
98beca42488374 Alexei Starovoitov 2021-09-16  6522  	core_relo.access_str_off = relo->access_str_off;
98beca42488374 Alexei Starovoitov 2021-09-16  6523  	core_relo.kind = relo->kind;
98beca42488374 Alexei Starovoitov 2021-09-16 @6524  	err = bpf_core_apply_relo_insn("prog_name", insn, 0, &core_relo, 0, btf, cands);
98beca42488374 Alexei Starovoitov 2021-09-16  6525  	btf_put(btf);
98beca42488374 Alexei Starovoitov 2021-09-16  6526  	return 0;
fab12a1832b619 Alexei Starovoitov 2021-09-08  6527  }
fab12a1832b619 Alexei Starovoitov 2021-09-08  6528  

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

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             reply	other threads:[~2021-09-19  9:44 UTC|newest]

Thread overview: 3+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-09-19  9:44 kernel test robot [this message]
2021-09-20  3:45 ` [ast-bpf:relo_core 5/11] kernel/bpf/btf.c:6524:2: warning: Value stored to 'err' is never read [clang-analyzer-deadcode.DeadStores] kernel test robot
2021-09-20  3:45   ` kernel test robot

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