diff mbox series

[7/8] mmap locking API: add MMAP_LOCK_INITIALIZER

Message ID 20200326070236.235835-8-walken@google.com (mailing list archive)
State New, archived
Headers show
Series Add a new mmap locking API wrapping mmap_sem calls | expand

Commit Message

Michel Lespinasse March 26, 2020, 7:02 a.m. UTC
Define a new initializer for the mmap locking api.
Initially this just evaluates to __RWSEM_INITIALIZER as the API
is defined as wrappers around rwsem.

Signed-off-by: Michel Lespinasse <walken@google.com>
---
 arch/x86/kernel/tboot.c    | 2 +-
 drivers/firmware/efi/efi.c | 2 +-
 include/linux/mmap_lock.h  | 2 ++
 mm/init-mm.c               | 2 +-
 4 files changed, 5 insertions(+), 3 deletions(-)

Comments

Laurent Dufour April 6, 2020, 9:46 a.m. UTC | #1
Le 26/03/2020 à 08:02, Michel Lespinasse a écrit :
> Define a new initializer for the mmap locking api.
> Initially this just evaluates to __RWSEM_INITIALIZER as the API
> is defined as wrappers around rwsem.

I can't see the benefit of this change.
The overall idea is to hide the mmap_sem name. Here the macro 
MMAP_LOCK_INITIALIZER() doesn't hide the name.

I think we can keep that in place until the real change of the mmap_sem to 
something else.

Cheers,
Laurent.

> 
> Signed-off-by: Michel Lespinasse <walken@google.com>
> ---
>   arch/x86/kernel/tboot.c    | 2 +-
>   drivers/firmware/efi/efi.c | 2 +-
>   include/linux/mmap_lock.h  | 2 ++
>   mm/init-mm.c               | 2 +-
>   4 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
> index b89f6ac6a0c0..4b79335624b1 100644
> --- a/arch/x86/kernel/tboot.c
> +++ b/arch/x86/kernel/tboot.c
> @@ -90,7 +90,7 @@ static struct mm_struct tboot_mm = {
>   	.pgd            = swapper_pg_dir,
>   	.mm_users       = ATOMIC_INIT(2),
>   	.mm_count       = ATOMIC_INIT(1),
> -	.mmap_sem       = __RWSEM_INITIALIZER(init_mm.mmap_sem),
> +	.mmap_sem       = MMAP_LOCK_INITIALIZER(init_mm.mmap_sem),
>   	.page_table_lock =  __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
>   	.mmlist         = LIST_HEAD_INIT(init_mm.mmlist),
>   };
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 21ea99f65113..5bdfe698cd7f 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -60,7 +60,7 @@ struct mm_struct efi_mm = {
>   	.mm_rb			= RB_ROOT,
>   	.mm_users		= ATOMIC_INIT(2),
>   	.mm_count		= ATOMIC_INIT(1),
> -	.mmap_sem		= __RWSEM_INITIALIZER(efi_mm.mmap_sem),
> +	.mmap_sem		= MMAP_LOCK_INITIALIZER(efi_mm.mmap_sem),
>   	.page_table_lock	= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
>   	.mmlist			= LIST_HEAD_INIT(efi_mm.mmlist),
>   	.cpu_bitmap		= { [BITS_TO_LONGS(NR_CPUS)] = 0},
> diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
> index 00d6cc02581d..7474b15bba38 100644
> --- a/include/linux/mmap_lock.h
> +++ b/include/linux/mmap_lock.h
> @@ -1,6 +1,8 @@
>   #ifndef _LINUX_MMAP_LOCK_H
>   #define _LINUX_MMAP_LOCK_H
>   
> +#define MMAP_LOCK_INITIALIZER(name) __RWSEM_INITIALIZER(name)
> +
>   static inline void mmap_init_lock(struct mm_struct *mm)
>   {
>   	init_rwsem(&mm->mmap_sem);
> diff --git a/mm/init-mm.c b/mm/init-mm.c
> index 19603302a77f..3c128bd6a30c 100644
> --- a/mm/init-mm.c
> +++ b/mm/init-mm.c
> @@ -31,7 +31,7 @@ struct mm_struct init_mm = {
>   	.pgd		= swapper_pg_dir,
>   	.mm_users	= ATOMIC_INIT(2),
>   	.mm_count	= ATOMIC_INIT(1),
> -	.mmap_sem	= __RWSEM_INITIALIZER(init_mm.mmap_sem),
> +	.mmap_sem	= MMAP_LOCK_INITIALIZER(init_mm.mmap_sem),
>   	.page_table_lock =  __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
>   	.arg_lock	=  __SPIN_LOCK_UNLOCKED(init_mm.arg_lock),
>   	.mmlist		= LIST_HEAD_INIT(init_mm.mmlist),
>
Michel Lespinasse April 6, 2020, 1:04 p.m. UTC | #2
On Mon, Apr 6, 2020 at 2:46 AM Laurent Dufour <ldufour@linux.ibm.com> wrote:
>
> Le 26/03/2020 à 08:02, Michel Lespinasse a écrit :
> > Define a new initializer for the mmap locking api.
> > Initially this just evaluates to __RWSEM_INITIALIZER as the API
> > is defined as wrappers around rwsem.
>
> I can't see the benefit of this change.
> The overall idea is to hide the mmap_sem name. Here the macro
> MMAP_LOCK_INITIALIZER() doesn't hide the name.

The idea for the initializer is that it makes it easier to change the
underlying implementation - if we do, we can change the initializer
without having to change every place where it is used. I actually do
that in my other patch series converting the mmap_sem to a range lock.

But you are correct that it does not help with renaming the mmap_sem
field - my next commit in this series still has to do that in every
place this initializer is used.
diff mbox series

Patch

diff --git a/arch/x86/kernel/tboot.c b/arch/x86/kernel/tboot.c
index b89f6ac6a0c0..4b79335624b1 100644
--- a/arch/x86/kernel/tboot.c
+++ b/arch/x86/kernel/tboot.c
@@ -90,7 +90,7 @@  static struct mm_struct tboot_mm = {
 	.pgd            = swapper_pg_dir,
 	.mm_users       = ATOMIC_INIT(2),
 	.mm_count       = ATOMIC_INIT(1),
-	.mmap_sem       = __RWSEM_INITIALIZER(init_mm.mmap_sem),
+	.mmap_sem       = MMAP_LOCK_INITIALIZER(init_mm.mmap_sem),
 	.page_table_lock =  __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
 	.mmlist         = LIST_HEAD_INIT(init_mm.mmlist),
 };
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 21ea99f65113..5bdfe698cd7f 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -60,7 +60,7 @@  struct mm_struct efi_mm = {
 	.mm_rb			= RB_ROOT,
 	.mm_users		= ATOMIC_INIT(2),
 	.mm_count		= ATOMIC_INIT(1),
-	.mmap_sem		= __RWSEM_INITIALIZER(efi_mm.mmap_sem),
+	.mmap_sem		= MMAP_LOCK_INITIALIZER(efi_mm.mmap_sem),
 	.page_table_lock	= __SPIN_LOCK_UNLOCKED(efi_mm.page_table_lock),
 	.mmlist			= LIST_HEAD_INIT(efi_mm.mmlist),
 	.cpu_bitmap		= { [BITS_TO_LONGS(NR_CPUS)] = 0},
diff --git a/include/linux/mmap_lock.h b/include/linux/mmap_lock.h
index 00d6cc02581d..7474b15bba38 100644
--- a/include/linux/mmap_lock.h
+++ b/include/linux/mmap_lock.h
@@ -1,6 +1,8 @@ 
 #ifndef _LINUX_MMAP_LOCK_H
 #define _LINUX_MMAP_LOCK_H
 
+#define MMAP_LOCK_INITIALIZER(name) __RWSEM_INITIALIZER(name)
+
 static inline void mmap_init_lock(struct mm_struct *mm)
 {
 	init_rwsem(&mm->mmap_sem);
diff --git a/mm/init-mm.c b/mm/init-mm.c
index 19603302a77f..3c128bd6a30c 100644
--- a/mm/init-mm.c
+++ b/mm/init-mm.c
@@ -31,7 +31,7 @@  struct mm_struct init_mm = {
 	.pgd		= swapper_pg_dir,
 	.mm_users	= ATOMIC_INIT(2),
 	.mm_count	= ATOMIC_INIT(1),
-	.mmap_sem	= __RWSEM_INITIALIZER(init_mm.mmap_sem),
+	.mmap_sem	= MMAP_LOCK_INITIALIZER(init_mm.mmap_sem),
 	.page_table_lock =  __SPIN_LOCK_UNLOCKED(init_mm.page_table_lock),
 	.arg_lock	=  __SPIN_LOCK_UNLOCKED(init_mm.arg_lock),
 	.mmlist		= LIST_HEAD_INIT(init_mm.mmlist),