[sj:damon/next 26/29] mm/damon/core.c:807:3: warning: variable 'err' is used uninitialized whenever 'if' condition is false
From: kernel test robot
Date: Wed Sep 21 2022 - 12:25:27 EST
tree: https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git damon/next
head: a5f85a5de8b74931ccd564bdb63194aedc99f2a9
commit: 71af589c839d9564a9daa6bb0af2f7f4931ea19c [26/29] mm/damon/core: separate damos application logic
config: hexagon-randconfig-r033-20220921 (https://download.01.org/0day-ci/archive/20220922/202209220049.dcCdIisb-lkp@xxxxxxxxx/config)
compiler: clang version 16.0.0 (https://github.com/llvm/llvm-project 791a7ae1ba3efd6bca96338e10ffde557ba83920)
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
# https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git/commit/?id=71af589c839d9564a9daa6bb0af2f7f4931ea19c
git remote add sj https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git
git fetch --no-tags sj damon/next
git checkout 71af589c839d9564a9daa6bb0af2f7f4931ea19c
# save the config file
mkdir build_dir && cp config build_dir/.config
COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross W=1 O=build_dir ARCH=hexagon SHELL=/bin/bash mm/damon/
If you fix the issue, kindly add following tag where applicable
| Reported-by: kernel test robot <lkp@xxxxxxxxx>
All warnings (new ones prefixed by >>):
>> mm/damon/core.c:807:3: warning: variable 'err' is used uninitialized whenever 'if' condition is false [-Wsometimes-uninitialized]
if (c->callback.before_scheme_apply)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:56:28: note: expanded from macro 'if'
#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:58:30: note: expanded from macro '__trace_if_var'
#define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
mm/damon/core.c:809:8: note: uninitialized use occurs here
if (!err)
^~~
include/linux/compiler.h:56:47: note: expanded from macro 'if'
#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
^~~~
include/linux/compiler.h:58:52: note: expanded from macro '__trace_if_var'
#define __trace_if_var(cond) (__builtin_constant_p(cond) ? (cond) : __trace_if_value(cond))
^~~~
mm/damon/core.c:807:3: note: remove the 'if' if its condition is always true
if (c->callback.before_scheme_apply)
^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
include/linux/compiler.h:56:23: note: expanded from macro 'if'
#define if(cond, ...) if ( __trace_if_var( !!(cond , ## __VA_ARGS__) ) )
^
mm/damon/core.c:787:9: note: initialize the variable 'err' to silence this warning
int err;
^
= 0
1 warning generated.
vim +807 mm/damon/core.c
b47f2bf827d3e3 SeongJae Park 2022-09-20 779
71af589c839d95 SeongJae Park 2022-09-20 780 static void damos_apply_scheme(struct damon_ctx *c, struct damon_target *t,
71af589c839d95 SeongJae Park 2022-09-20 781 struct damon_region *r, struct damos *s)
b47f2bf827d3e3 SeongJae Park 2022-09-20 782 {
b47f2bf827d3e3 SeongJae Park 2022-09-20 783 struct damos_quota *quota = &s->quota;
71af589c839d95 SeongJae Park 2022-09-20 784 unsigned long sz = r->ar.end - r->ar.start;
b47f2bf827d3e3 SeongJae Park 2022-09-20 785 struct timespec64 begin, end;
b47f2bf827d3e3 SeongJae Park 2022-09-20 786 unsigned long sz_applied = 0;
71af589c839d95 SeongJae Park 2022-09-20 787 int err;
b47f2bf827d3e3 SeongJae Park 2022-09-20 788
f7d911c39cbbb8 SeongJae Park 2022-03-22 789 if (c->ops.apply_scheme) {
71af589c839d95 SeongJae Park 2022-09-20 790 if (quota->esz && quota->charged_sz + sz > quota->esz) {
1cd2430300594a SeongJae Park 2021-11-05 791 sz = ALIGN_DOWN(quota->esz - quota->charged_sz,
2b8a248d587334 SeongJae Park 2021-11-05 792 DAMON_MIN_REGION);
2b8a248d587334 SeongJae Park 2021-11-05 793 if (!sz)
2b8a248d587334 SeongJae Park 2021-11-05 794 goto update_stat;
2886230666fa8b SeongJae Park 2022-08-14 795 if (sz >= r->ar.end - r->ar.start) {
2886230666fa8b SeongJae Park 2022-08-14 796 pr_err("sz: %lu, region: %lu-%lu (%lu), quota: %lu, charged: %lu\n",
2886230666fa8b SeongJae Park 2022-08-14 797 sz, r->ar.start,
2886230666fa8b SeongJae Park 2022-08-14 798 r->ar.end, r->ar.end -
2886230666fa8b SeongJae Park 2022-08-14 799 r->ar.start,
2886230666fa8b SeongJae Park 2022-08-14 800 quota->esz,
2886230666fa8b SeongJae Park 2022-08-14 801 quota->charged_sz);
2886230666fa8b SeongJae Park 2022-08-14 802 BUG();
2886230666fa8b SeongJae Park 2022-08-14 803 }
4ed9824346c071 Kaixu Xia 2022-08-13 804 damon_split_region_at(t, r, sz);
2b8a248d587334 SeongJae Park 2021-11-05 805 }
1cd2430300594a SeongJae Park 2021-11-05 806 ktime_get_coarse_ts64(&begin);
5cb21aeba065d6 SeongJae Park 2022-09-20 @807 if (c->callback.before_scheme_apply)
71af589c839d95 SeongJae Park 2022-09-20 808 err = c->callback.before_scheme_apply(c, t, r, s);
5cb21aeba065d6 SeongJae Park 2022-09-20 809 if (!err)
f7d911c39cbbb8 SeongJae Park 2022-03-22 810 sz_applied = c->ops.apply_scheme(c, t, r, s);
1cd2430300594a SeongJae Park 2021-11-05 811 ktime_get_coarse_ts64(&end);
1cd2430300594a SeongJae Park 2021-11-05 812 quota->total_charged_ns += timespec64_to_ns(&end) -
1cd2430300594a SeongJae Park 2021-11-05 813 timespec64_to_ns(&begin);
2b8a248d587334 SeongJae Park 2021-11-05 814 quota->charged_sz += sz;
1cd2430300594a SeongJae Park 2021-11-05 815 if (quota->esz && quota->charged_sz >= quota->esz) {
50585192bc2ef9 SeongJae Park 2021-11-05 816 quota->charge_target_from = t;
50585192bc2ef9 SeongJae Park 2021-11-05 817 quota->charge_addr_from = r->ar.end + 1;
50585192bc2ef9 SeongJae Park 2021-11-05 818 }
2b8a248d587334 SeongJae Park 2021-11-05 819 }
2f0b548c9f03a7 SeongJae Park 2021-11-05 820 if (s->action != DAMOS_STAT)
1f366e421c8f69 SeongJae Park 2021-11-05 821 r->age = 0;
2b8a248d587334 SeongJae Park 2021-11-05 822
2b8a248d587334 SeongJae Park 2021-11-05 823 update_stat:
0e92c2ee9f4595 SeongJae Park 2022-01-14 824 s->stat.nr_tried++;
0e92c2ee9f4595 SeongJae Park 2022-01-14 825 s->stat.sz_tried += sz;
0e92c2ee9f4595 SeongJae Park 2022-01-14 826 if (sz_applied)
0e92c2ee9f4595 SeongJae Park 2022-01-14 827 s->stat.nr_applied++;
0e92c2ee9f4595 SeongJae Park 2022-01-14 828 s->stat.sz_applied += sz_applied;
1f366e421c8f69 SeongJae Park 2021-11-05 829 }
71af589c839d95 SeongJae Park 2022-09-20 830
:::::: The code at line 807 was first introduced by commit
:::::: 5cb21aeba065d632fa56295d75151d6b70a2bd1b mm/damon/core: add a DAMON callback for scheme target regions check
:::::: TO: SeongJae Park <sj@xxxxxxxxxx>
:::::: CC: SeongJae Park <sj@xxxxxxxxxx>
--
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https://01.org/lkp