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* [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG.
@ 2021-03-30 12:07 zhouchuangao
  2021-04-12 13:04 ` Jessica Yu
  0 siblings, 1 reply; 7+ messages in thread
From: zhouchuangao @ 2021-03-30 12:07 UTC (permalink / raw)
  To: Jessica Yu, linux-kernel; +Cc: zhouchuangao

It can be optimized at compile time.

Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
---
 kernel/module.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 3047935..f46fc4f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1014,8 +1014,8 @@ void __symbol_put(const char *symbol)
 	};
 
 	preempt_disable();
-	if (!find_symbol(&fsa))
-		BUG();
+	BUG_ON(!find_symbol(&fsa));
+
 	module_put(fsa.owner);
 	preempt_enable();
 }
-- 
2.7.4


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG.
  2021-03-30 12:07 [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG zhouchuangao
@ 2021-04-12 13:04 ` Jessica Yu
  2021-04-13  7:21   ` 周传高
  0 siblings, 1 reply; 7+ messages in thread
From: Jessica Yu @ 2021-04-12 13:04 UTC (permalink / raw)
  To: zhouchuangao; +Cc: linux-kernel

+++ zhouchuangao [30/03/21 05:07 -0700]:
>It can be optimized at compile time.
>
>Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>

Hi,

Could you please provide a more descriptive changelog? I.e., Is this
a fix for a cocinelle warning? What are the optimization(s)?

Thanks,

Jessica

>---
> kernel/module.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
>diff --git a/kernel/module.c b/kernel/module.c
>index 3047935..f46fc4f 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -1014,8 +1014,8 @@ void __symbol_put(const char *symbol)
> 	};
>
> 	preempt_disable();
>-	if (!find_symbol(&fsa))
>-		BUG();
>+	BUG_ON(!find_symbol(&fsa));
>+
> 	module_put(fsa.owner);
> 	preempt_enable();
> }
>-- 
>2.7.4
>

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re:Re: [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG.
  2021-04-12 13:04 ` Jessica Yu
@ 2021-04-13  7:21   ` 周传高
  2021-04-13 12:42     ` Jessica Yu
  0 siblings, 1 reply; 7+ messages in thread
From: 周传高 @ 2021-04-13  7:21 UTC (permalink / raw)
  To: Jessica Yu; +Cc: linux-kernel


>+++ zhouchuangao [30/03/21 05:07 -0700]:
>>It can be optimized at compile time.
>>
>>Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
>
>Hi,
>
>Could you please provide a more descriptive changelog? I.e., Is this
>a fix for a cocinelle warning? What are the optimization(s)?
>
>Thanks,
>
First, 
This patch comes from cocinelle warning.

Second,
#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)

BUG_ON uses unlikely in if(). Through disassembly, we can see that
brk #0x800 is compiled to the end of the function.
As you can see below:
    ......
    ffffff8008660bec:   d65f03c0    ret
    ffffff8008660bf0:   d4210000    brk #0x800

Usually, the condition in if () is not satisfied. For the multi-stage pipeline, 
we do not need to perform fetch decode and excute operation on brk 
instruction.

In my opinion, this can improve the efficiency of the multi-stage pipeline.

Thanks,
zhouchuangao

>Jessica
>
>>---
>> kernel/module.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>>diff --git a/kernel/module.c b/kernel/module.c
>>index 3047935..f46fc4f 100644
>>--- a/kernel/module.c
>>+++ b/kernel/module.c
>>@@ -1014,8 +1014,8 @@ void __symbol_put(const char *symbol)
>> 	};
>>
>> 	preempt_disable();
>>-	if (!find_symbol(&fsa))
>>-		BUG();
>>+	BUG_ON(!find_symbol(&fsa));
>>+
>> 	module_put(fsa.owner);
>> 	preempt_enable();
>> }
>>-- 
>>2.7.4
>>



^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: Re: [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG.
  2021-04-13  7:21   ` 周传高
@ 2021-04-13 12:42     ` Jessica Yu
  0 siblings, 0 replies; 7+ messages in thread
From: Jessica Yu @ 2021-04-13 12:42 UTC (permalink / raw)
  To: 周传高; +Cc: linux-kernel

+++ 周传高 [13/04/21 15:21 +0800]:
>
>>+++ zhouchuangao [30/03/21 05:07 -0700]:
>>>It can be optimized at compile time.
>>>
>>>Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
>>
>>Hi,
>>
>>Could you please provide a more descriptive changelog? I.e., Is this
>>a fix for a cocinelle warning? What are the optimization(s)?
>>
>>Thanks,
>>
>First,
>This patch comes from cocinelle warning.
>
>Second,
>#define BUG_ON(condition) do { if (unlikely(condition)) BUG(); } while (0)
>
>BUG_ON uses unlikely in if(). Through disassembly, we can see that
>brk #0x800 is compiled to the end of the function.
>As you can see below:
>    ......
>    ffffff8008660bec:   d65f03c0    ret
>    ffffff8008660bf0:   d4210000    brk #0x800
>
>Usually, the condition in if () is not satisfied. For the multi-stage pipeline,
>we do not need to perform fetch decode and excute operation on brk
>instruction.
>
>In my opinion, this can improve the efficiency of the multi-stage pipeline.

Thanks. Could you please modify your commit/changelog message to
include this information (including the coccinelle warning) and resend
the patch?

^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG
  2021-05-10  1:38 zhouchuangao
@ 2021-05-12 12:54 ` Jessica Yu
  0 siblings, 0 replies; 7+ messages in thread
From: Jessica Yu @ 2021-05-12 12:54 UTC (permalink / raw)
  To: zhouchuangao; +Cc: linux-kernel

+++ zhouchuangao [09/05/21 18:38 -0700]:
>This patch comes from cocinelle warning.

Please include the output of the cocinelle warning here as well.

See commit 56149c8cd820 ("media: pci: saa7164-core.c: replace if
(cond) BUG() with BUG_ON()") for an example. Thanks.

>BUG_ON uses unlikely in if(). Through disassembly, we can see that
>brk #0x800 is compiled to the end of the function.
>As you can see below:
>    ......
>    ffffff8008660bec:   d65f03c0    ret
>    ffffff8008660bf0:   d4210000    brk #0x800
>
>Usually, the condition in if () is not satisfied. For the
>multi-stage pipeline, we do not need to perform fetch decode
>and excute operation on brk instruction.
>
>In my opinion, this can improve the efficiency of the
>multi-stage pipeline.
>
>Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
>---
> kernel/module.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/kernel/module.c b/kernel/module.c
>index b5dd92e..faf9114 100644
>--- a/kernel/module.c
>+++ b/kernel/module.c
>@@ -1014,8 +1014,7 @@ void __symbol_put(const char *symbol)
> 	};
>
> 	preempt_disable();
>-	if (!find_symbol(&fsa))
>-		BUG();
>+	BUG_ON(!find_symbol(&fsa));
> 	module_put(fsa.owner);
> 	preempt_enable();
> }
>-- 
>2.7.4
>

^ permalink raw reply	[flat|nested] 7+ messages in thread

* [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG
@ 2021-05-10  1:38 zhouchuangao
  2021-05-12 12:54 ` Jessica Yu
  0 siblings, 1 reply; 7+ messages in thread
From: zhouchuangao @ 2021-05-10  1:38 UTC (permalink / raw)
  To: jeyu; +Cc: linux-kernel, zhouchuangao

This patch comes from cocinelle warning.

BUG_ON uses unlikely in if(). Through disassembly, we can see that
brk #0x800 is compiled to the end of the function.
As you can see below:
    ......
    ffffff8008660bec:   d65f03c0    ret
    ffffff8008660bf0:   d4210000    brk #0x800

Usually, the condition in if () is not satisfied. For the
multi-stage pipeline, we do not need to perform fetch decode
and excute operation on brk instruction.

In my opinion, this can improve the efficiency of the
multi-stage pipeline.

Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
---
 kernel/module.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index b5dd92e..faf9114 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1014,8 +1014,7 @@ void __symbol_put(const char *symbol)
 	};
 
 	preempt_disable();
-	if (!find_symbol(&fsa))
-		BUG();
+	BUG_ON(!find_symbol(&fsa));
 	module_put(fsa.owner);
 	preempt_enable();
 }
-- 
2.7.4


^ permalink raw reply	[flat|nested] 7+ messages in thread

* [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG.
@ 2021-04-17 10:22 zhouchuangao
  0 siblings, 0 replies; 7+ messages in thread
From: zhouchuangao @ 2021-04-17 10:22 UTC (permalink / raw)
  To: Jessica Yu, linux-kernel; +Cc: zhouchuangao

First:
This patch comes from cocinelle warning.

Second:
BUG_ON uses unlikely in if(). Through disassembly, we can see that
brk #0x800 is compiled to the end of the function.
As you can see below:
    ......
    ffffff8008660bec:   d65f03c0    ret
    ffffff8008660bf0:   d4210000    brk #0x800

Usually, the condition in if () is not satisfied. For the
multi-stage pipeline, we do not need to perform fetch decode
and excute operation on brk instruction.

In my opinion, this can improve the efficiency of the
multi-stage pipeline.

Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
---
 kernel/module.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/kernel/module.c b/kernel/module.c
index 3047935..f46fc4f 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1014,8 +1014,8 @@ void __symbol_put(const char *symbol)
 	};
 
 	preempt_disable();
-	if (!find_symbol(&fsa))
-		BUG();
+	BUG_ON(!find_symbol(&fsa));
+
 	module_put(fsa.owner);
 	preempt_enable();
 }
-- 
2.7.4


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2021-05-12 12:55 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2021-03-30 12:07 [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG zhouchuangao
2021-04-12 13:04 ` Jessica Yu
2021-04-13  7:21   ` 周传高
2021-04-13 12:42     ` Jessica Yu
2021-04-17 10:22 zhouchuangao
2021-05-10  1:38 zhouchuangao
2021-05-12 12:54 ` Jessica Yu

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