Hi

Den tis 23 juni 2020 11:22John Garry <john.garry@huawei.com> skrev:

> On 23/06/2020 02:07, kernel test robot wrote:
>
> + Rikard, as the GENMASK compile-time sanity checks were added recently
>
> > Hi John,
> >
> > I love your patch! Perhaps something to improve:
> >
> > [auto build test WARNING on iommu/next]
> > [If your patch is applied to the wrong git tree, kindly drop us a note.
> > And when submitting patch, we suggest to use  as documented in
> > https://git-scm.com/docs/git-format-patch]
> >
> > url:
> https://github.com/0day-ci/linux/commits/John-Garry/iommu-arm-smmu-v3-Improve-cmdq-lock-efficiency/20200623-013438
> > base:   https://git.kernel.org/pub/scm/linux/kernel/git/joro/iommu.git
> next
> > config: arm64-randconfig-c024-20200622 (attached as .config)
> > compiler: aarch64-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>
> >
> > All warnings (new ones prefixed by >>, old ones prefixed by <<):
> >
> > In file included from include/linux/bits.h:23,
> > from include/linux/ioport.h:15,
> > from include/linux/acpi.h:12,
> > from drivers/iommu/arm-smmu-v3.c:12:
> > drivers/iommu/arm-smmu-v3.c: In function 'arm_smmu_cmdq_issue_cmdlist':
> > 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)))
>
> I'd say that GENMASK_INPUT_CHECK() should be able to handle a l=0 and
> h=unsigned value, so I doubt this warn.
>
> Using GENMASK((int)cmdq->q.llq.max_n_shift, 0) resolves it, but it looks
> like GENMASK_INPUT_CHECK() could be improved.
>

Indeed it could, it is fixed in -next.

Rikard

> |                            ^
> > 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))
> > |   ^~~~~~~~~~~~~~~~~~~
> >>> drivers/iommu/arm-smmu-v3.c:1404:18: note: in expansion of macro
> 'GENMASK'
> > 1404 |  u32 prod_mask = GENMASK(cmdq->q.llq.max_n_shift, 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))
> > |   ^~~~~~~~~~~~~~~~~~~
> >>> drivers/iommu/arm-smmu-v3.c:1404:18: note: in expansion of macro
> 'GENMASK'
> > 1404 |  u32 prod_mask = GENMASK(cmdq->q.llq.max_n_shift, 0);
> > |                  ^~~~~~~
> >
> > vim +/GENMASK +1404 drivers/iommu/arm-smmu-v3.c
>
>
>