* [PATCH] resource: Elide a conversion warning on 32-bit
@ 2024-07-29 15:16 Palmer Dabbelt
2024-07-29 15:38 ` Ilpo Järvinen
0 siblings, 1 reply; 2+ messages in thread
From: Palmer Dabbelt @ 2024-07-29 15:16 UTC (permalink / raw)
To: bhelgaas
Cc: andriy.shevchenko, mika.westerberg, ilpo.jarvinen, Greg KH, bhe,
alison.schofield, Palmer Dabbelt, linux-kernel
From: Palmer Dabbelt <palmer@rivosinc.com>
I recently ended up with a warning on some compilers along the lines of
CC kernel/resource.o
In file included from include/linux/ioport.h:16,
from kernel/resource.c:15:
kernel/resource.c: In function 'gfr_start':
include/linux/minmax.h:49:37: error: conversion from 'long long unsigned int' to 'resource_size_t' {aka 'unsigned int'} changes value from '17179869183' to '4294967295' [-Werror=overflow]
49 | ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
| ^
include/linux/minmax.h:52:9: note: in expansion of macro '__cmp_once_unique'
52 | __cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
| ^~~~~~~~~~~~~~~~~
include/linux/minmax.h:161:27: note: in expansion of macro '__cmp_once'
161 | #define min_t(type, x, y) __cmp_once(min, type, x, y)
| ^~~~~~~~~~
kernel/resource.c:1829:23: note: in expansion of macro 'min_t'
1829 | end = min_t(resource_size_t, base->end,
| ^~~~~
kernel/resource.c: In function 'gfr_continue':
include/linux/minmax.h:49:37: error: conversion from 'long long unsigned int' to 'resource_size_t' {aka 'unsigned int'} changes value from '17179869183' to '4294967295' [-Werror=overflow]
49 | ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
| ^
include/linux/minmax.h:52:9: note: in expansion of macro '__cmp_once_unique'
52 | __cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
| ^~~~~~~~~~~~~~~~~
include/linux/minmax.h:161:27: note: in expansion of macro '__cmp_once'
161 | #define min_t(type, x, y) __cmp_once(min, type, x, y)
| ^~~~~~~~~~
kernel/resource.c:1847:24: note: in expansion of macro 'min_t'
1847 | addr <= min_t(resource_size_t, base->end,
| ^~~~~
cc1: all warnings being treated as errors
which this elides via an extra cast.
Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
---
Not sure if there's a better way to do this, but I didn't see any
reports yet and my tester is failing so I figured it'd be best to get
something on the lists.
---
kernel/resource.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/kernel/resource.c b/kernel/resource.c
index 14777afb0a99..6459561b746e 100644
--- a/kernel/resource.c
+++ b/kernel/resource.c
@@ -1845,7 +1845,7 @@ static bool gfr_continue(struct resource *base, resource_size_t addr,
*/
return addr > addr - size &&
addr <= min_t(resource_size_t, base->end,
- (1ULL << MAX_PHYSMEM_BITS) - 1);
+ (resource_size_t)((1ULL << MAX_PHYSMEM_BITS) - 1));
}
static resource_size_t gfr_next(resource_size_t addr, resource_size_t size,
--
2.45.2
^ permalink raw reply related [flat|nested] 2+ messages in thread* Re: [PATCH] resource: Elide a conversion warning on 32-bit
2024-07-29 15:16 [PATCH] resource: Elide a conversion warning on 32-bit Palmer Dabbelt
@ 2024-07-29 15:38 ` Ilpo Järvinen
0 siblings, 0 replies; 2+ messages in thread
From: Ilpo Järvinen @ 2024-07-29 15:38 UTC (permalink / raw)
To: Palmer Dabbelt
Cc: bhelgaas, Andy Shevchenko, Mika Westerberg, Greg KH, bhe,
alison.schofield, LKML
On Mon, 29 Jul 2024, Palmer Dabbelt wrote:
> From: Palmer Dabbelt <palmer@rivosinc.com>
>
> I recently ended up with a warning on some compilers along the lines of
>
> CC kernel/resource.o
> In file included from include/linux/ioport.h:16,
> from kernel/resource.c:15:
> kernel/resource.c: In function 'gfr_start':
> include/linux/minmax.h:49:37: error: conversion from 'long long unsigned int' to 'resource_size_t' {aka 'unsigned int'} changes value from '17179869183' to '4294967295' [-Werror=overflow]
> 49 | ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
> | ^
> include/linux/minmax.h:52:9: note: in expansion of macro '__cmp_once_unique'
> 52 | __cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
> | ^~~~~~~~~~~~~~~~~
> include/linux/minmax.h:161:27: note: in expansion of macro '__cmp_once'
> 161 | #define min_t(type, x, y) __cmp_once(min, type, x, y)
> | ^~~~~~~~~~
> kernel/resource.c:1829:23: note: in expansion of macro 'min_t'
> 1829 | end = min_t(resource_size_t, base->end,
> | ^~~~~
> kernel/resource.c: In function 'gfr_continue':
> include/linux/minmax.h:49:37: error: conversion from 'long long unsigned int' to 'resource_size_t' {aka 'unsigned int'} changes value from '17179869183' to '4294967295' [-Werror=overflow]
> 49 | ({ type ux = (x); type uy = (y); __cmp(op, ux, uy); })
> | ^
> include/linux/minmax.h:52:9: note: in expansion of macro '__cmp_once_unique'
> 52 | __cmp_once_unique(op, type, x, y, __UNIQUE_ID(x_), __UNIQUE_ID(y_))
> | ^~~~~~~~~~~~~~~~~
> include/linux/minmax.h:161:27: note: in expansion of macro '__cmp_once'
> 161 | #define min_t(type, x, y) __cmp_once(min, type, x, y)
> | ^~~~~~~~~~
> kernel/resource.c:1847:24: note: in expansion of macro 'min_t'
> 1847 | addr <= min_t(resource_size_t, base->end,
> | ^~~~~
> cc1: all warnings being treated as errors
>
> which this elides via an extra cast.
I think you should describe the configuration which triggers this a bit
more here because it's not just about 32-bit build but also requires
MAX_PHYSMEM_BITS to be larger than 32.
> Signed-off-by: Palmer Dabbelt <palmer@rivosinc.com>
> ---
> Not sure if there's a better way to do this, but I didn't see any
> reports yet and my tester is failing so I figured it'd be best to get
> something on the lists.
> ---
> kernel/resource.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/resource.c b/kernel/resource.c
> index 14777afb0a99..6459561b746e 100644
> --- a/kernel/resource.c
> +++ b/kernel/resource.c
> @@ -1845,7 +1845,7 @@ static bool gfr_continue(struct resource *base, resource_size_t addr,
> */
> return addr > addr - size &&
> addr <= min_t(resource_size_t, base->end,
> - (1ULL << MAX_PHYSMEM_BITS) - 1);
> + (resource_size_t)((1ULL << MAX_PHYSMEM_BITS) - 1));
So this effectively casts away 2 bits hiding the warning? It would be
more proper to limit it with RESOURCE_SIZE_MAX instead of casting the
bits away if that's the intention of this code (of which I'm not sure).
And why are you fixing just one line when there is another similar
expression?
--
i.
^ permalink raw reply [flat|nested] 2+ messages in thread
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2024-07-29 15:16 [PATCH] resource: Elide a conversion warning on 32-bit Palmer Dabbelt
2024-07-29 15:38 ` Ilpo Järvinen
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