mm/slab.c:3880:12: warning: Same expression on both sides of '&&' because 'limit' and 'shared' represent the same value.

mm/slab.c:3880:12: warning: Same expression on both sides of '&&' because 'limit' and 'shared' represent the same value.

[kernel test robot]

[-- Attachment #1: Type: text/plain, Size: 6773 bytes --]

CC: kbuild-all(a)lists.01.org
CC: linux-kernel(a)vger.kernel.org
TO: "Paul E. McKenney" <paulmck@kernel.org>

tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
head:   f69d02e37a85645aa90d18cacfff36dba370f797
commit: 8e7f37f2aaa56b723a24f6872817cf9c6410b613 mm: Add mem_dump_obj() to print source of memory block
date:   6 weeks ago
:::::: branch date: 24 hours ago
:::::: commit date: 6 weeks ago
compiler: mips64el-linux-gcc (GCC) 9.3.0

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


"cppcheck warnings: (new ones prefixed by >>)"
   mm/slab.c:3309:7: warning: Redundant assignment of 'objp' to itself. [selfAssignment]
    objp = cache_alloc_debugcheck_after(cachep, flags, objp, caller);
         ^
   mm/slab.c:3442:7: warning: Redundant assignment of 'objp' to itself. [selfAssignment]
    objp = cache_free_debugcheck(cachep, objp, caller);
         ^
   mm/slab.c:3502:8: warning: Redundant assignment of 'p[i]' to itself. [selfAssignment]
     p[i] = cache_alloc_debugcheck_after(s, flags, p[i], caller);
          ^

cppcheck possible warnings: (new ones prefixed by >>, may not real problems)

>> mm/slab.c:3880:12: warning: Same expression on both sides of '&&' because 'limit' and 'shared' represent the same value. [knownConditionTrueFalse]
    if (limit && shared && batchcount)
              ^
   mm/slab.c:3872:14: note: 'limit' is assigned value '0' here.
    int limit = 0;
                ^
   mm/slab.c:3873:15: note: 'shared' is assigned value '0' here.
    int shared = 0;
                 ^
   mm/slab.c:3880:12: note: Same expression on both sides of '&&' because 'limit' and 'shared' represent the same value.
    if (limit && shared && batchcount)
              ^
>> mm/slab.c:3880:22: warning: Same expression on both sides of '&&' because 'batchcount' and 'shared' represent the same value. [knownConditionTrueFalse]
    if (limit && shared && batchcount)
                        ^
   mm/slab.c:3874:19: note: 'batchcount' is assigned value '0' here.
    int batchcount = 0;
                     ^
   mm/slab.c:3873:15: note: 'shared' is assigned value '0' here.
    int shared = 0;
                 ^
   mm/slab.c:3880:22: note: Same expression on both sides of '&&' because 'batchcount' and 'shared' represent the same value.
    if (limit && shared && batchcount)
                        ^

vim +3880 mm/slab.c

^1da177e4c3f41 Linus Torvalds    2005-04-16  3867  
18004c5d4084d9 Christoph Lameter 2012-07-06  3868  /* Called with slab_mutex held always */
83b519e8b9572c Pekka Enberg      2009-06-10  3869  static int enable_cpucache(struct kmem_cache *cachep, gfp_t gfp)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3870  {
^1da177e4c3f41 Linus Torvalds    2005-04-16  3871  	int err;
943a451a87d229 Glauber Costa     2012-12-18  3872  	int limit = 0;
943a451a87d229 Glauber Costa     2012-12-18  3873  	int shared = 0;
943a451a87d229 Glauber Costa     2012-12-18  3874  	int batchcount = 0;
943a451a87d229 Glauber Costa     2012-12-18  3875  
7c00fce98c3e15 Thomas Garnier    2016-07-26  3876  	err = cache_random_seq_create(cachep, cachep->num, gfp);
c7ce4f60ac199f Thomas Garnier    2016-05-19  3877  	if (err)
c7ce4f60ac199f Thomas Garnier    2016-05-19  3878  		goto end;
c7ce4f60ac199f Thomas Garnier    2016-05-19  3879  
943a451a87d229 Glauber Costa     2012-12-18 @3880  	if (limit && shared && batchcount)
943a451a87d229 Glauber Costa     2012-12-18  3881  		goto skip_setup;
a737b3e2fcf96f Andrew Morton     2006-03-22  3882  	/*
a737b3e2fcf96f Andrew Morton     2006-03-22  3883  	 * The head array serves three purposes:
^1da177e4c3f41 Linus Torvalds    2005-04-16  3884  	 * - create a LIFO ordering, i.e. return objects that are cache-warm
^1da177e4c3f41 Linus Torvalds    2005-04-16  3885  	 * - reduce the number of spinlock operations.
^1da177e4c3f41 Linus Torvalds    2005-04-16  3886  	 * - reduce the number of linked list operations on the slab and
^1da177e4c3f41 Linus Torvalds    2005-04-16  3887  	 *   bufctl chains: array operations are cheaper.
^1da177e4c3f41 Linus Torvalds    2005-04-16  3888  	 * The numbers are guessed, we should auto-tune as described by
^1da177e4c3f41 Linus Torvalds    2005-04-16  3889  	 * Bonwick.
^1da177e4c3f41 Linus Torvalds    2005-04-16  3890  	 */
3b0efdfa1e7193 Christoph Lameter 2012-06-13  3891  	if (cachep->size > 131072)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3892  		limit = 1;
3b0efdfa1e7193 Christoph Lameter 2012-06-13  3893  	else if (cachep->size > PAGE_SIZE)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3894  		limit = 8;
3b0efdfa1e7193 Christoph Lameter 2012-06-13  3895  	else if (cachep->size > 1024)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3896  		limit = 24;
3b0efdfa1e7193 Christoph Lameter 2012-06-13  3897  	else if (cachep->size > 256)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3898  		limit = 54;
^1da177e4c3f41 Linus Torvalds    2005-04-16  3899  	else
^1da177e4c3f41 Linus Torvalds    2005-04-16  3900  		limit = 120;
^1da177e4c3f41 Linus Torvalds    2005-04-16  3901  
a737b3e2fcf96f Andrew Morton     2006-03-22  3902  	/*
a737b3e2fcf96f Andrew Morton     2006-03-22  3903  	 * CPU bound tasks (e.g. network routing) can exhibit cpu bound
^1da177e4c3f41 Linus Torvalds    2005-04-16  3904  	 * allocation behaviour: Most allocs on one cpu, most free operations
^1da177e4c3f41 Linus Torvalds    2005-04-16  3905  	 * on another cpu. For these cases, an efficient object passing between
^1da177e4c3f41 Linus Torvalds    2005-04-16  3906  	 * cpus is necessary. This is provided by a shared array. The array
^1da177e4c3f41 Linus Torvalds    2005-04-16  3907  	 * replaces Bonwick's magazine layer.
^1da177e4c3f41 Linus Torvalds    2005-04-16  3908  	 * On uniprocessor, it's functionally equivalent (but less efficient)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3909  	 * to a larger limit. Thus disabled by default.
^1da177e4c3f41 Linus Torvalds    2005-04-16  3910  	 */
^1da177e4c3f41 Linus Torvalds    2005-04-16  3911  	shared = 0;
3b0efdfa1e7193 Christoph Lameter 2012-06-13  3912  	if (cachep->size <= PAGE_SIZE && num_possible_cpus() > 1)
^1da177e4c3f41 Linus Torvalds    2005-04-16  3913  		shared = 8;
^1da177e4c3f41 Linus Torvalds    2005-04-16  3914  

:::::: The code at line 3880 was first introduced by commit
:::::: 943a451a87d229ca564a27274b58eaeae35fde5d slab: propagate tunable values

:::::: TO: Glauber Costa <glommer@parallels.com>
:::::: CC: Linus Torvalds <torvalds@linux-foundation.org>

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