* [PATCH -next v3] bcache: use DEFINE_MUTEX() for mutex lock
@ 2021-04-07 12:50 Zheng Yongjun
2021-04-07 12:54 ` Pavel Goran
0 siblings, 1 reply; 2+ messages in thread
From: Zheng Yongjun @ 2021-04-07 12:50 UTC (permalink / raw)
To: colyli, kent.overstreet, linux-bcache, linux-kernel
Cc: Zheng Yongjun, Hulk Robot
mutex lock can be initialized automatically with DEFINE_MUTEX() rather
than explicitly calling mutex_init().
this patch will reduce the size of bcache.ko about 16 bytes, the reason
as follows:
though this patch will increase the size of .data segment about 32 bytes,
it will also reduce the size of .init.text and .rodata.str1.1(at x86_64),
.rodata_str1.8(at arm64) and .bss segment total about 48 bytes which reduce
the size more than .data segment;
here is the statistics:
Sections: (arm64 platform)
Idx name size
-.init.text 00000240
+.init.text 00000228
-.rodata.str1.8 000012cd
+.rodata.str1.8 000012b5
-.data 00000c60
+.data 00000c80
Sections: (x86 platform)
Idx name size
-.init.text 000001d9
+.init.text 000001bf
-.rodata.str1.1 00000c80
+.rodata.str1.1 00000c6d
-.data 00000cc0
+.data 00000ce0
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
---
v3:
- change commit log, delete statistic about .bss segment.
v2:
- add commit log about the reason why bcache.ko size reduced.
drivers/md/bcache/super.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
index 03e1fe4de53d..3635f454309e 100644
--- a/drivers/md/bcache/super.c
+++ b/drivers/md/bcache/super.c
@@ -40,7 +40,7 @@ static const char invalid_uuid[] = {
};
static struct kobject *bcache_kobj;
-struct mutex bch_register_lock;
+DEFINE_MUTEX(bch_register_lock);
bool bcache_is_reboot;
LIST_HEAD(bch_cache_sets);
static LIST_HEAD(uncached_devices);
@@ -2869,7 +2869,6 @@ static int __init bcache_init(void)
check_module_parameters();
- mutex_init(&bch_register_lock);
init_waitqueue_head(&unregister_wait);
register_reboot_notifier(&reboot);
--
2.25.1
^ permalink raw reply related [flat|nested] 2+ messages in thread
* Re: [PATCH -next v3] bcache: use DEFINE_MUTEX() for mutex lock
2021-04-07 12:50 [PATCH -next v3] bcache: use DEFINE_MUTEX() for mutex lock Zheng Yongjun
@ 2021-04-07 12:54 ` Pavel Goran
0 siblings, 0 replies; 2+ messages in thread
From: Pavel Goran @ 2021-04-07 12:54 UTC (permalink / raw)
To: Zheng Yongjun
Cc: colyli, kent.overstreet, linux-bcache, linux-kernel, Hulk Robot
Hello Zheng,
The third paragraph of the commit description still mentions the .bss
segment.
Wednesday, April 7, 2021, 7:50:00 PM, you wrote:
> mutex lock can be initialized automatically with DEFINE_MUTEX() rather
> than explicitly calling mutex_init().
> this patch will reduce the size of bcache.ko about 16 bytes, the reason
> as follows:
> though this patch will increase the size of .data segment about 32 bytes,
> it will also reduce the size of .init.text and .rodata.str1.1(at x86_64),
> .rodata_str1.8(at arm64) and .bss segment total about 48 bytes which reduce
> the size more than .data segment;
> here is the statistics:
> Sections: (arm64 platform)
> Idx name size
> -.init.text 00000240
> +.init.text 00000228
> -.rodata.str1.8 000012cd
> +.rodata.str1.8 000012b5
> -.data 00000c60
> +.data 00000c80
> Sections: (x86 platform)
> Idx name size
> -.init.text 000001d9
> +.init.text 000001bf
> -.rodata.str1.1 00000c80
> +.rodata.str1.1 00000c6d
> -.data 00000cc0
> +.data 00000ce0
> Reported-by: Hulk Robot <hulkci@huawei.com>
> Signed-off-by: Zheng Yongjun <zhengyongjun3@huawei.com>
> ---
> v3:
> - change commit log, delete statistic about .bss segment.
> v2:
> - add commit log about the reason why bcache.ko size reduced.
> drivers/md/bcache/super.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
> diff --git a/drivers/md/bcache/super.c b/drivers/md/bcache/super.c
> index 03e1fe4de53d..3635f454309e 100644
> --- a/drivers/md/bcache/super.c
> +++ b/drivers/md/bcache/super.c
> @@ -40,7 +40,7 @@ static const char invalid_uuid[] = {
> };
>
> static struct kobject *bcache_kobj;
> -struct mutex bch_register_lock;
> +DEFINE_MUTEX(bch_register_lock);
> bool bcache_is_reboot;
> LIST_HEAD(bch_cache_sets);
> static LIST_HEAD(uncached_devices);
> @@ -2869,7 +2869,6 @@ static int __init bcache_init(void)
>
> check_module_parameters();
>
> - mutex_init(&bch_register_lock);
> init_waitqueue_head(&unregister_wait);
> register_reboot_notifier(&reboot);
>
Pavel Goran
^ permalink raw reply [flat|nested] 2+ messages in thread
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