2010-08-10 14:58:10

by Namhyung Kim

Subject: [PATCH] percpu: use INT_MAX as sentinel value of unit_map

unit_map is a pointer to int so it would be more reasonable to use INT_MAX
as sentinel value.

Signed-off-by: Namhyung Kim <[email protected]>
---
mm/percpu.c | 6 +++---
1 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/mm/percpu.c b/mm/percpu.c
index 6470e77..9581f84 100644
--- a/mm/percpu.c
+++ b/mm/percpu.c
@@ -1390,7 +1390,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
unit_off = alloc_bootmem(nr_cpu_ids * sizeof(unit_off[0]));

for (cpu = 0; cpu < nr_cpu_ids; cpu++)
- unit_map[cpu] = UINT_MAX;
+ unit_map[cpu] = INT_MAX;
pcpu_first_unit_cpu = NR_CPUS;

for (group = 0, unit = 0; group < ai->nr_groups; group++, unit += i) {
@@ -1406,7 +1406,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,

PCPU_SETUP_BUG_ON(cpu > nr_cpu_ids);
PCPU_SETUP_BUG_ON(!cpu_possible(cpu));
- PCPU_SETUP_BUG_ON(unit_map[cpu] != UINT_MAX);
+ PCPU_SETUP_BUG_ON(unit_map[cpu] != INT_MAX);

unit_map[cpu] = unit + i;
unit_off[cpu] = gi->base_offset + i * ai->unit_size;
@@ -1419,7 +1419,7 @@ int __init pcpu_setup_first_chunk(const struct pcpu_alloc_info *ai,
pcpu_nr_units = unit;

for_each_possible_cpu(cpu)
- PCPU_SETUP_BUG_ON(unit_map[cpu] == UINT_MAX);
+ PCPU_SETUP_BUG_ON(unit_map[cpu] == INT_MAX);

/* we're done parsing the input, undefine BUG macro and dump config */
#undef PCPU_SETUP_BUG_ON
--
1.7.0.4

2010-08-10 15:08:38

by Tejun Heo

Subject: Re: [PATCH] percpu: use INT_MAX as sentinel value of unit_map

On 08/10/2010 04:58 PM, Namhyung Kim wrote:
> unit_map is a pointer to int so it would be more reasonable to use INT_MAX
> as sentinel value.
>
> Signed-off-by: Namhyung Kim <[email protected]>

Hmmm... yeah unit_map used to be uint. I'd much prefer -1 (which
would actually result in the same code BTW) over INT_MAX tho.

Thanks.

--
tejun