Re: drivers/base/regmap/regcache-maple.c:114:23: warning: 'upper_index' is used uninitialized
From: Geert Uytterhoeven
Date: Tue Jul 25 2023 - 05:06:43 EST
Hi Robot,
On Tue, Jul 25, 2023 at 10:17 AM kernel test robot <lkp@xxxxxxxxx> wrote:
> FYI, the error/warning still remains.
>
> tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> head: 0b5547c51827e053cc754db47d3ec3e6c2c451d2
> commit: f033c26de5a5734625d2dd1dc196745fae186f1b regmap: Add maple tree based register cache
> date: 4 months ago
> config: arc-randconfig-r001-20230725 (https://download.01.org/0day-ci/archive/20230725/202307251518.4JYwdU5r-lkp@xxxxxxxxx/config)
> compiler: arc-elf-gcc (GCC) 12.3.0
> reproduce: (https://download.01.org/0day-ci/archive/20230725/202307251518.4JYwdU5r-lkp@xxxxxxxxx/reproduce)
>
> If you fix the issue in a separate patch/commit (i.e. not just a new version of
> the same patch/commit), kindly add following tags
> | Reported-by: kernel test robot <lkp@xxxxxxxxx>
> | Closes: https://lore.kernel.org/oe-kbuild-all/202307251518.4JYwdU5r-lkp@xxxxxxxxx/
>
> All warnings (new ones prefixed by >>):
>
> drivers/base/regmap/regcache-maple.c: In function 'regcache_maple_drop':
> >> drivers/base/regmap/regcache-maple.c:114:23: warning: 'upper_index' is used uninitialized [-Wuninitialized]
> 114 | unsigned long upper_index, upper_last;
> | ^~~~~~~~~~~
> >> drivers/base/regmap/regcache-maple.c:114:36: warning: 'upper_last' is used uninitialized [-Wuninitialized]
> 114 | unsigned long upper_index, upper_last;
> | ^~~~~~~~~~
> drivers/base/regmap/regcache-maple.c:113:23: warning: 'lower_index' is used uninitialized [-Wuninitialized]
> 113 | unsigned long lower_index, lower_last;
> | ^~~~~~~~~~~
> drivers/base/regmap/regcache-maple.c:113:36: warning: 'lower_last' is used uninitialized [-Wuninitialized]
> 113 | unsigned long lower_index, lower_last;
> | ^~~~~~~~~~
These are false positives...
>
>
> vim +/upper_index +114 drivers/base/regmap/regcache-maple.c
>
> 106
> 107 static int regcache_maple_drop(struct regmap *map, unsigned int min,
> 108 unsigned int max)
> 109 {
> 110 struct maple_tree *mt = map->cache;
> 111 MA_STATE(mas, mt, min, max);
> 112 unsigned long *entry, *lower, *upper;
> 113 unsigned long lower_index, lower_last;
> > 114 unsigned long upper_index, upper_last;
> 115 int ret;
> 116
> 117 lower = NULL;
> 118 upper = NULL;
> 119
> 120 mas_lock(&mas);
> 121
> 122 mas_for_each(&mas, entry, max) {
> 123 /*
> 124 * This is safe because the regmap lock means the
> 125 * Maple lock is redundant, but we need to take it due
> 126 * to lockdep asserts in the maple tree code.
> 127 */
> 128 mas_unlock(&mas);
> 129
> 130 /* Do we need to save any of this entry? */
> 131 if (mas.index < min) {
> 132 lower_index = mas.index;
> 133 lower_last = min -1;
> 134
> 135 lower = kmemdup(entry, ((min - mas.index) *
> 136 sizeof(unsigned long)),
> 137 GFP_KERNEL);
lower{,_index,_last} and ...
> 138 if (!lower) {
> 139 ret = -ENOMEM;
> 140 goto out;
> 141 }
> 142 }
> 143
> 144 if (mas.last > max) {
> 145 upper_index = max + 1;
> 146 upper_last = mas.last;
> 147
> 148 upper = kmemdup(&entry[max + 1],
> 149 ((mas.last - max) *
> 150 sizeof(unsigned long)),
> 151 GFP_KERNEL);
upper{,_index,_last} are always initialized together, ...
> 152 if (!upper) {
> 153 ret = -ENOMEM;
> 154 goto out;
> 155 }
> 156 }
> 157
> 158 kfree(entry);
> 159 mas_lock(&mas);
> 160 mas_erase(&mas);
> 161
> 162 /* Insert new nodes with the saved data */
> 163 if (lower) {
but these gatekeepers...
> 164 mas_set_range(&mas, lower_index, lower_last);
> 165 ret = mas_store_gfp(&mas, lower, GFP_KERNEL);
> 166 if (ret != 0)
> 167 goto out;
> 168 lower = NULL;
> 169 }
> 170
> 171 if (upper) {
check only one of them (which are preinitialized at lines 117/118).
> 172 mas_set_range(&mas, upper_index, upper_last);
> 173 ret = mas_store_gfp(&mas, upper, GFP_KERNEL);
> 174 if (ret != 0)
> 175 goto out;
> 176 upper = NULL;
> 177 }
> 178 }
> 179
> 180 out:
> 181 mas_unlock(&mas);
> 182 kfree(lower);
> 183 kfree(upper);
> 184
> 185 return ret;
> 186 }
> 187
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds