Re: Re: [PATCH] kernel/module: Use BUG_ON instead of if condition followed by BUG.

[Jessica Yu]

+++ 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@xxxxxxxx>
> >
> > 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?