On 8/18/20 12:23 PM, Luc Van Oostenryck wrote: > On Tue, Aug 18, 2020 at 11:09:52AM -0700, Randy Dunlap wrote: >> Hi, >> >> On kernel 5.9-rc1, either i386 or x86_64 builds, I am seeing these >> sparse warnings: >> >> ../drivers/gpu/drm/ast/ast_cursor.c:256:26: CK: warning: duplicate [noderef] >> ../drivers/gpu/drm/ast/ast_cursor.c:256:26: CK: error: multiple address space given: __iomem & __iomem >> >> for this source line: >> >> u8 __iomem *dst, __iomem *sig; >> >> >> Should one of those __iomem-s be removed? > > I think so. It's a bit like writing > int const *a, const *b; > or > int unsigned *a, unsigned *b; > >> I.e., does "__iomem" apply to everything after it, up to the ending ';', >> or just up to the next comma ','? > > The (simplified) syntax for declarations is: > declaration: > declaration-specifiers [init-declarator-list] ; > init-declarator-list: > init-declarator > init-declarator-list , init-declarator > init-declarator > declarator > declarator = initializer > declarator: > [pointer] direct-declarator > pointer: > * [type-qualifier-list] > * [type-qualifier-list] pointer > direct-declarator: > identifier > ... > > Essentially, attributes are type modifiers, some acting like > qualifiers and others are more like specifiers. But qualifiers > and specifiers are never allowed directly after the comma because > they appertain to the declaration-specifier part of the declaration. > So, yes, the first __iomem applies to the whole declaration and > the second one should be removed. > > But maybe it's not 100% clear and the best should be to use a > separate declaration for each variable? Yes, that was my patch plan. :) Thanks for the explanation. -- ~Randy
