# \[PATCH -next v4\] bcache: Use DEFINE\_MUTEX() for mutex lock - Subsystems: BCACHE (BLOCK LAYER CACHE), THE REST - Maintainers: Coly Li, Kent Overstreet, Linus Torvalds - List: linux-bcache - 3 messages, 2 authors - Page: https://ratatoskr.run/linux-bcache/2021/05/6358193/t ## \[PATCH -next v4\] bcache: Use DEFINE\_MUTEX() for mutex lock - From: Zheng Yongjun \ - Date: 2021-05-05 10:53:15 - Message: https://ratatoskr.run/linux-bcache/2021/05/6358193.md ```text 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) 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 Signed-off-by: Zheng Yongjun --- v4: - change commit log, delete bss information at commit description. 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 ``` ## Re: \[PATCH -next v4\] bcache: Use DEFINE\_MUTEX() for mutex lock - From: Coly Li \ - Date: 2021-05-06 03:27:12 - Message: https://ratatoskr.run/linux-bcache/2021/05/6359492.md ```text On 5/5/21 7:06 PM, Zheng Yongjun 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) 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 > Signed-off-by: Zheng Yongjun Added in my for-test queue. Thanks. Coly Li [snipped] ``` ## 答复: \[PATCH -next v4\] bcache: Use DEFINE\_MUTEX() for mutex lock - From: zhengyongjun \ - Date: 2021-05-06 08:33:21 - Message: https://ratatoskr.run/linux-bcache/2021/05/6359654.md ```text I've been on a business trip some time ago and didn't do upstream work. Thanks for your patience:) -----邮件原件----- 发件人: Coly Li [mailto:colyli@suse.de] 发送时间: 2021年5月6日 11:27 收件人: zhengyongjun [ref] 抄送: pmail_hulkci [ref]; kent.overstreet@gmail.com; linux-bcache@vger.kernel.org; linux-kernel@vger.kernel.org 主题: Re: [PATCH -next v4] bcache: Use DEFINE_MUTEX() for mutex lock On 5/5/21 7:06 PM, Zheng Yongjun 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) 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 > Signed-off-by: Zheng Yongjun Added in my for-test queue. Thanks. Coly Li [snipped] ```