On Fri 06-04-18 23:38:09, Stefan Agner wrote:
> So far code was using ULLONG_MAX and type casting to obtain a
> phys_addr_t with all bits set. The typecast is necessary to
> silence compiler warnings on 32-bit platforms.
>
> Use the simpler but still type safe approach "~(phys_addr_t)0"
> to create a preprocessor define for all bits set.
>
> Suggested-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
> Signed-off-by: Stefan Agner <stefan@xxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
> ---
> Hi,
>
> There are about a dozen other instances of (phys_addr_t)ULLONG_MAX
> accross the tree. Should I address them too?
Yes, please. Maybe wait until the merge window sattles (rc1).
> --
> Stefan
>
> include/linux/kernel.h | 1 +
> mm/memblock.c | 22 +++++++++++-----------
> 2 files changed, 12 insertions(+), 11 deletions(-)
>
> diff --git a/include/linux/kernel.h b/include/linux/kernel.h
> index 3fd291503576..1ba9e2d71bc9 100644
> --- a/include/linux/kernel.h
> +++ b/include/linux/kernel.h
> @@ -29,6 +29,7 @@
> #define LLONG_MIN (-LLONG_MAX - 1)
> #define ULLONG_MAX (~0ULL)
> #define SIZE_MAX (~(size_t)0)
> +#define PHYS_ADDR_MAX (~(phys_addr_t)0)
>
> #define U8_MAX ((u8)~0U)
> #define S8_MAX ((s8)(U8_MAX>>1))
> diff --git a/mm/memblock.c b/mm/memblock.c
> index 696829a198ba..957587178b36 100644
> --- a/mm/memblock.c
> +++ b/mm/memblock.c
> @@ -67,7 +67,7 @@ ulong __init_memblock choose_memblock_flags(void)
> /* adjust *@size so that (@base + *@size) doesn't overflow, return new size */
> static inline phys_addr_t memblock_cap_size(phys_addr_t base, phys_addr_t *size)
> {
> - return *size = min(*size, (phys_addr_t)ULLONG_MAX - base);
> + return *size = min(*size, PHYS_ADDR_MAX - base);
> }
>
> /*
> @@ -924,7 +924,7 @@ void __init_memblock __next_mem_range(u64 *idx, int nid, ulong flags,
> r = &type_b->regions[idx_b];
> r_start = idx_b ? r[-1].base + r[-1].size : 0;
> r_end = idx_b < type_b->cnt ?
> - r->base : (phys_addr_t)ULLONG_MAX;
> + r->base : PHYS_ADDR_MAX;
>
> /*
> * if idx_b advanced past idx_a,
> @@ -1040,7 +1040,7 @@ void __init_memblock __next_mem_range_rev(u64 *idx, int nid, ulong flags,
> r = &type_b->regions[idx_b];
> r_start = idx_b ? r[-1].base + r[-1].size : 0;
> r_end = idx_b < type_b->cnt ?
> - r->base : (phys_addr_t)ULLONG_MAX;
> + r->base : PHYS_ADDR_MAX;
> /*
> * if idx_b advanced past idx_a,
> * break out to advance idx_a
> @@ -1543,13 +1543,13 @@ phys_addr_t __init_memblock memblock_end_of_DRAM(void)
>
> static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
> {
> - phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
> + phys_addr_t max_addr = PHYS_ADDR_MAX;
> struct memblock_region *r;
>
> /*
> * translate the memory @limit size into the max address within one of
> * the memory memblock regions, if the @limit exceeds the total size
> - * of those regions, max_addr will keep original value ULLONG_MAX
> + * of those regions, max_addr will keep original value PHYS_ADDR_MAX
> */
> for_each_memblock(memory, r) {
> if (limit <= r->size) {
> @@ -1564,7 +1564,7 @@ static phys_addr_t __init_memblock __find_max_addr(phys_addr_t limit)
>
> void __init memblock_enforce_memory_limit(phys_addr_t limit)
> {
> - phys_addr_t max_addr = (phys_addr_t)ULLONG_MAX;
> + phys_addr_t max_addr = PHYS_ADDR_MAX;
>
> if (!limit)
> return;
> @@ -1572,14 +1572,14 @@ void __init memblock_enforce_memory_limit(phys_addr_t limit)
> max_addr = __find_max_addr(limit);
>
> /* @limit exceeds the total size of the memory, do nothing */
> - if (max_addr == (phys_addr_t)ULLONG_MAX)
> + if (max_addr == PHYS_ADDR_MAX)
> return;
>
> /* truncate both memory and reserved regions */
> memblock_remove_range(&memblock.memory, max_addr,
> - (phys_addr_t)ULLONG_MAX);
> + PHYS_ADDR_MAX);
> memblock_remove_range(&memblock.reserved, max_addr,
> - (phys_addr_t)ULLONG_MAX);
> + PHYS_ADDR_MAX);
> }
>
> void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
> @@ -1607,7 +1607,7 @@ void __init memblock_cap_memory_range(phys_addr_t base, phys_addr_t size)
> /* truncate the reserved regions */
> memblock_remove_range(&memblock.reserved, 0, base);
> memblock_remove_range(&memblock.reserved,
> - base + size, (phys_addr_t)ULLONG_MAX);
> + base + size, PHYS_ADDR_MAX);
> }
>
> void __init memblock_mem_limit_remove_map(phys_addr_t limit)
> @@ -1620,7 +1620,7 @@ void __init memblock_mem_limit_remove_map(phys_addr_t limit)
> max_addr = __find_max_addr(limit);
>
> /* @limit exceeds the total size of the memory, do nothing */
> - if (max_addr == (phys_addr_t)ULLONG_MAX)
> + if (max_addr == PHYS_ADDR_MAX)
> return;
>
> memblock_cap_memory_range(0, max_addr);
> --
> 2.17.0
>
--
Michal Hocko
SUSE Labs
