tree: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master head: 625d3449788f85569096780592549d0340e9c0c7 commit: 295bcca84916cb5079140a89fccb472bb8d1f6e2 linux/bits.h: add compile time sanity check of GENMASK inputs date: 3 months ago config: i386-randconfig-r012-20200622 (attached as .config) compiler: gcc-9 (Debian 9.3.0-13) 9.3.0 reproduce (this is a W=1 build): git checkout 295bcca84916cb5079140a89fccb472bb8d1f6e2 # save the attached .config to linux build tree make W=1 ARCH=i386 If you fix the issue, kindly add following tag as appropriate Reported-by: kernel test robot <lkp(a)intel.com&gt; All warnings (new ones prefixed by >>, old ones prefixed by <<): In file included from include/linux/bitfield.h:10, from drivers/iio/adc/meson_saradc.c:8: drivers/iio/adc/meson_saradc.c: In function 'meson_sar_adc_read_raw_sample': include/linux/bits.h:26:28: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits] 26 | __builtin_constant_p((l) > (h)), (l) > (h), 0))) | ^ include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO' 16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); }))) | ^ include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK' 39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l)) | ^~~~~~~~~~~~~~~~~~~ 371 | fifo_val &= GENMASK(priv->param->resolution - 1, 0); | ^~~~~~~ include/linux/bits.h:26:40: warning: comparison of unsigned expression < 0 is always false [-Wtype-limits] 26 | __builtin_constant_p((l) > (h)), (l) > (h), 0))) | ^ include/linux/build_bug.h:16:62: note: in definition of macro 'BUILD_BUG_ON_ZERO' 16 | #define BUILD_BUG_ON_ZERO(e) ((int)(sizeof(struct { int:(-!!(e)); }))) | ^ include/linux/bits.h:39:3: note: in expansion of macro 'GENMASK_INPUT_CHECK' 39 | (GENMASK_INPUT_CHECK(h, l) + __GENMASK(h, l)) | ^~~~~~~~~~~~~~~~~~~ 371 | fifo_val &= GENMASK(priv->param->resolution - 1, 0); | ^~~~~~~ vim +/GENMASK +371 drivers/iio/adc/meson_saradc.c 3adbf34273306f Martin Blumenstingl 2017-01-22 342 3adbf34273306f Martin Blumenstingl 2017-01-22 343 static int meson_sar_adc_read_raw_sample(struct iio_dev *indio_dev, 3adbf34273306f Martin Blumenstingl 2017-01-22 344 const struct iio_chan_spec *chan, 3adbf34273306f Martin Blumenstingl 2017-01-22 345 int *val) 3adbf34273306f Martin Blumenstingl 2017-01-22 346 { 3adbf34273306f Martin Blumenstingl 2017-01-22 347 struct meson_sar_adc_priv *priv = iio_priv(indio_dev); 6a882a2cbeb09b Heiner Kallweit 2017-02-15 348 int regval, fifo_chan, fifo_val, count; 3adbf34273306f Martin Blumenstingl 2017-01-22 349 3af109131b7eb8 Heiner Kallweit 2017-02-15 350 if(!wait_for_completion_timeout(&priv->done, 3af109131b7eb8 Heiner Kallweit 2017-02-15 351 msecs_to_jiffies(MESON_SAR_ADC_TIMEOUT))) 3af109131b7eb8 Heiner Kallweit 2017-02-15 352 return -ETIMEDOUT; 3adbf34273306f Martin Blumenstingl 2017-01-22 353 6a882a2cbeb09b Heiner Kallweit 2017-02-15 354 count = meson_sar_adc_get_fifo_count(indio_dev); 6a882a2cbeb09b Heiner Kallweit 2017-02-15 355 if (count != 1) { 6a882a2cbeb09b Heiner Kallweit 2017-02-15 356 dev_err(&indio_dev->dev, 6a882a2cbeb09b Heiner Kallweit 2017-02-15 357 "ADC FIFO has %d element(s) instead of one\n", count); 6a882a2cbeb09b Heiner Kallweit 2017-02-15 358 return -EINVAL; 3adbf34273306f Martin Blumenstingl 2017-01-22 359 } 3adbf34273306f Martin Blumenstingl 2017-01-22 360 6a882a2cbeb09b Heiner Kallweit 2017-02-15 361 regmap_read(priv->regmap, MESON_SAR_ADC_FIFO_RD, &regval); 6a882a2cbeb09b Heiner Kallweit 2017-02-15 362 fifo_chan = FIELD_GET(MESON_SAR_ADC_FIFO_RD_CHAN_ID_MASK, regval); 827df0571fb32d Martin Blumenstingl 2018-09-25 363 if (fifo_chan != chan->address) { 6a882a2cbeb09b Heiner Kallweit 2017-02-15 364 dev_err(&indio_dev->dev, 827df0571fb32d Martin Blumenstingl 2018-09-25 365 "ADC FIFO entry belongs to channel %d instead of %lu\n", 827df0571fb32d Martin Blumenstingl 2018-09-25 366 fifo_chan, chan->address); 6a882a2cbeb09b Heiner Kallweit 2017-02-15 367 return -EINVAL; 6a882a2cbeb09b Heiner Kallweit 2017-02-15 368 } 3adbf34273306f Martin Blumenstingl 2017-01-22 369 6a882a2cbeb09b Heiner Kallweit 2017-02-15 370 fifo_val = FIELD_GET(MESON_SAR_ADC_FIFO_RD_SAMPLE_VALUE_MASK, regval); 057e5a1109faa0 Martin Blumenstingl 2018-09-23 @371 fifo_val &= GENMASK(priv->param->resolution - 1, 0); 48ba7c3c0b3736 Heiner Kallweit 2017-03-18 372 *val = meson_sar_adc_calib_val(indio_dev, fifo_val); 3adbf34273306f Martin Blumenstingl 2017-01-22 373 3adbf34273306f Martin Blumenstingl 2017-01-22 374 return 0; 3adbf34273306f Martin Blumenstingl 2017-01-22 375 } 3adbf34273306f Martin Blumenstingl 2017-01-22 376 :::::: The code at line 371 was first introduced by commit :::::: 057e5a1109faa01091a989c224833e2df6003b2e iio: adc: meson-saradc: simplify access to meson_sar_adc_param :::::: TO: Martin Blumenstingl <martin.blumenstingl(a)googlemail.com&gt; :::::: CC: Jonathan Cameron <Jonathan.Cameron(a)huawei.com&gt; --- 0-DAY CI Kernel Test Service, Intel Corporation https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org