On Thu, Apr 04, 2024 at 01:13:41PM +0300, Mike Rapoport wrote:
>On Wed, Apr 03, 2024 at 09:10:45AM +0000, Wei Yang wrote:
>> The dummy entry is introduced in the initial implementation of lmb in
>> commit 7c8c6b9776fb ("powerpc: Merge lmb.c and make MM initialization
>> use it.").
>>
>> As the comment says the empty dummy entry is to simplify the code.
>>
>> /* Create a dummy zero size LMB which will get coalesced away later.
>> * This simplifies the lmb_add() code below...
>> */
>>
>> While current code is reimplemented by Tejun in commit 784656f9c680
>> ("memblock: Reimplement memblock_add_region()"). This empty dummy entry
>> seems not benefit the code any more.
>>
>> Let's remove it.
>>
>> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
>> CC: Paul Mackerras <paulus@xxxxxxxxxx>
>> CC: Tejun Heo <tj@xxxxxxxxxx>
>> CC: Mike Rapoport <rppt@xxxxxxxxxx>
>> ---
>> mm/memblock.c | 18 +++---------------
>> tools/testing/memblock/tests/basic_api.c | 8 ++++----
>> tools/testing/memblock/tests/common.c | 4 ++--
>> 3 files changed, 9 insertions(+), 21 deletions(-)
>>
>> diff --git a/mm/memblock.c b/mm/memblock.c
>> index d09136e040d3..100d3b7ab499 100644
>> --- a/mm/memblock.c
>> +++ b/mm/memblock.c
>> @@ -114,12 +114,12 @@ static struct memblock_region memblock_physmem_init_regions[INIT_PHYSMEM_REGIONS
>>
>> struct memblock memblock __initdata_memblock = {
>> .memory.regions = memblock_memory_init_regions,
>> - .memory.cnt = 1, /* empty dummy entry */
>> + .memory.cnt = 0,
>
>No need to set memory.cnt to 0, this line can be just removed
>
>> .memory.max = INIT_MEMBLOCK_MEMORY_REGIONS,
>> .memory.name = "memory",
>>
>> .reserved.regions = memblock_reserved_init_regions,
>> - .reserved.cnt = 1, /* empty dummy entry */
>> + .reserved.cnt = 0,
>
>Ditto.
>
>> .reserved.max = INIT_MEMBLOCK_RESERVED_REGIONS,
>> .reserved.name = "reserved",
>>
>> @@ -130,7 +130,7 @@ struct memblock memblock __initdata_memblock = {
>> #ifdef CONFIG_HAVE_MEMBLOCK_PHYS_MAP
>> struct memblock_type physmem = {
>> .regions = memblock_physmem_init_regions,
>> - .cnt = 1, /* empty dummy entry */
>> + .cnt = 0,
>
>Ditto.
>
>> .max = INIT_PHYSMEM_REGIONS,
>> .name = "physmem",
>> };
>> @@ -356,7 +356,6 @@ static void __init_memblock memblock_remove_region(struct memblock_type *type, u
>> /* Special case for empty arrays */
>> if (type->cnt == 0) {
>> WARN_ON(type->total_size != 0);
>> - type->cnt = 1;
>> type->regions[0].base = 0;
>> type->regions[0].size = 0;
>> type->regions[0].flags = 0;
>> @@ -598,17 +597,6 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
>> if (!size)
>> return 0;
>>
>> - /* special case for empty array */
>> - if (type->regions[0].size == 0) {
>> - WARN_ON(type->cnt != 1 || type->total_size);
>> - type->regions[0].base = base;
>> - type->regions[0].size = size;
>> - type->regions[0].flags = flags;
>> - memblock_set_region_node(&type->regions[0], nid);
>> - type->total_size = size;
>> - return 0;
>> - }
>
>I'd keep the special case for empty array, just update it for new semantics
>of type->cnt.
>
>> -
>> /*
>> * The worst case is when new range overlaps all existing regions,
>> * then we'll need type->cnt + 1 empty regions in @type. So if
>> diff --git a/tools/testing/memblock/tests/basic_api.c b/tools/testing/memblock/tests/basic_api.c
>> index 57bf2688edfd..f317fe691fc4 100644
>> --- a/tools/testing/memblock/tests/basic_api.c
>> +++ b/tools/testing/memblock/tests/basic_api.c
>> @@ -15,12 +15,12 @@ static int memblock_initialization_check(void)
>> PREFIX_PUSH();
>>
>> ASSERT_NE(memblock.memory.regions, NULL);
>> - ASSERT_EQ(memblock.memory.cnt, 1);
>> + ASSERT_EQ(memblock.memory.cnt, 0);
>> ASSERT_EQ(memblock.memory.max, EXPECTED_MEMBLOCK_REGIONS);
>> ASSERT_EQ(strcmp(memblock.memory.name, "memory"), 0);
>>
>> ASSERT_NE(memblock.reserved.regions, NULL);
>> - ASSERT_EQ(memblock.reserved.cnt, 1);
>> + ASSERT_EQ(memblock.reserved.cnt, 0);
>> ASSERT_EQ(memblock.memory.max, EXPECTED_MEMBLOCK_REGIONS);
>> ASSERT_EQ(strcmp(memblock.reserved.name, "reserved"), 0);
>>
>> @@ -1295,7 +1295,7 @@ static int memblock_remove_only_region_check(void)
>> ASSERT_EQ(rgn->base, 0);
>> ASSERT_EQ(rgn->size, 0);
>>
>> - ASSERT_EQ(memblock.memory.cnt, 1);
>> + ASSERT_EQ(memblock.memory.cnt, 0);
>> ASSERT_EQ(memblock.memory.total_size, 0);
>>
>> test_pass_pop();
>> @@ -1723,7 +1723,7 @@ static int memblock_free_only_region_check(void)
>> ASSERT_EQ(rgn->base, 0);
>> ASSERT_EQ(rgn->size, 0);
>>
>> - ASSERT_EQ(memblock.reserved.cnt, 1);
>> + ASSERT_EQ(memblock.reserved.cnt, 0);
>> ASSERT_EQ(memblock.reserved.total_size, 0);
>>
>> test_pass_pop();
>> diff --git a/tools/testing/memblock/tests/common.c b/tools/testing/memblock/tests/common.c
>> index f43b6f414983..4fa94b281280 100644
>> --- a/tools/testing/memblock/tests/common.c
>> +++ b/tools/testing/memblock/tests/common.c
>> @@ -40,13 +40,13 @@ void reset_memblock_regions(void)
>> {
>> memset(memblock.memory.regions, 0,
>> memblock.memory.cnt * sizeof(struct memblock_region));
>> - memblock.memory.cnt = 1;
>> + memblock.memory.cnt = 0;
>
>Here as well, no need to initialize to 0.
>
Sure, I'd prepare v2.
>> memblock.memory.max = INIT_MEMBLOCK_REGIONS;
>> memblock.memory.total_size = 0;
>>
>> memset(memblock.reserved.regions, 0,
>> memblock.reserved.cnt * sizeof(struct memblock_region));
>> - memblock.reserved.cnt = 1;
>> + memblock.reserved.cnt = 0;
>> memblock.reserved.max = INIT_MEMBLOCK_RESERVED_REGIONS;
>> memblock.reserved.total_size = 0;
>> }
>> --
>> 2.34.1
>>
>
>--
>Sincerely yours,
>Mike.
--
Wei Yang
Help you, Help me
