On 2021/6/18 6:41, Jason Gunthorpe wrote: > On Thu, Jun 17, 2021 at 03:31:44PM +0800, Weihang Li wrote: >> From: Lang Cheng <chenglang@xxxxxxxxxx> >> >> Fix complains from sparse about "dubious: x & !y" when calling >> hr_reg_write(ctx, field, !!val). > > Where is this from? > > I'm not convinced you should have the temporary here given how much > magics are involved in this stuff that rely on builtin_constant_p > > Jason > The warning comes from: #define __BF_FIELD_CHECK(_mask, _reg, _val, _pfx) \ ... BUILD_BUG_ON_MSG(__builtin_constant_p(_val) ? \ ~((_mask) >> __bf_shf(_mask)) & (_val) : 0, \ _pfx "value too large for the field"); \ I will change 'hr_reg_write(ctx, field, !!val)' to 'hr_reg_write(ctx, field, val ? 1 : 0)'. The latter is not as succinct as the former, but can avoid the sparse warning. Thanks Weihang
