| Message ID | 20240403091045.12009-1-richard.weiyang@gmail.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/memblock: remove empty dummy entry | expand |
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@gmail.com> > CC: Paul Mackerras <paulus@ozlabs.org> > CC: Tejun Heo <tj@kernel.org> > CC: Mike Rapoport <rppt@kernel.org> > --- > 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. > 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 >
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@gmail.com> >> CC: Paul Mackerras <paulus@ozlabs.org> >> CC: Tejun Heo <tj@kernel.org> >> CC: Mike Rapoport <rppt@kernel.org> >> --- >> 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.
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@gmail.com> >> CC: Paul Mackerras <paulus@ozlabs.org> >> CC: Tejun Heo <tj@kernel.org> >> CC: Mike Rapoport <rppt@kernel.org> >> --- >> 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. > Oops, I found maybe we should keep this. Since reset_memblock_regions is called on each new round test, we should clear it. >> 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.
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, .memory.max = INIT_MEMBLOCK_MEMORY_REGIONS, .memory.name = "memory", .reserved.regions = memblock_reserved_init_regions, - .reserved.cnt = 1, /* empty dummy entry */ + .reserved.cnt = 0, .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, .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; - } - /* * 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; 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; }
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> --- 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(-)