mm/memblock: remove empty dummy entry

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@gmail.com>
CC: Paul Mackerras <paulus@ozlabs.org>
CC: Tejun Heo <tj@kernel.org>
CC: Mike Rapoport <rppt@kernel.org>
Link: https://lore.kernel.org/r/20240405015821.13411-1-richard.weiyang@gmail.com
Signed-off-by: Mike Rapoport (IBM) <rppt@kernel.org>

diff --git a/mm/memblock.c b/mm/memblock.c
index d09136e040d3cc37b1b7b74a7cdd5d2c92eb8cb7..98d25689cf102ff8a495ac444f3131402a95a185 100644 (file)
--- a/mm/memblock.c
+++ b/mm/memblock.c
@@ -114,12 +114,10 @@ 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.max             = INIT_MEMBLOCK_MEMORY_REGIONS,
        .memory.name            = "memory",
 
        .reserved.regions       = memblock_reserved_init_regions,
-       .reserved.cnt           = 1,    /* empty dummy entry */
        .reserved.max           = INIT_MEMBLOCK_RESERVED_REGIONS,
        .reserved.name          = "reserved",
 
@@ -130,7 +128,6 @@ 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 */
        .max                    = INIT_PHYSMEM_REGIONS,
        .name                   = "physmem",
 };
@@ -356,7 +353,6 @@ 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;
@@ -600,12 +596,13 @@ static int __init_memblock memblock_add_range(struct memblock_type *type,
 
        /* special case for empty array */
        if (type->regions[0].size == 0) {
-               WARN_ON(type->cnt != 1 || type->total_size);
+               WARN_ON(type->cnt != 0 || 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;
+               type->cnt = 1;
                return 0;
        }
 

diff --git a/tools/testing/memblock/tests/basic_api.c b/tools/testing/memblock/tests/basic_api.c
index 57bf2688edfd68ca8dbc5724da1e78aff9897e59..f317fe691fc44766aa4aa4eb675ad2ed9128791a 100644 (file)
--- 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 f43b6f414983d60bf2176e6951cc6703296f0ea7..c2c569f121782ee127167dcf72049c0449e2402f 100644 (file)
--- 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;
        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;
 }