Re: drivers/base/regmap/regcache-maple.c:114:23: warning: 'upper_index' is used uninitialized
From: Liu, Yujie
Date: Tue Jul 25 2023 - 05:35:29 EST
Hi Geert,
On Tue, 2023-07-25 at 11:06 +0200, Geert Uytterhoeven wrote:
> 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...
Sorry for the noise. We've configured the bot to filter out these false
positives.
Thanks,
Yujie
> >
> >
> > 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
>