linux-kernel - Re: mmotm 2020-05-13-20-30 uploaded (objtool warnings)

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Date:   Fri, 29 May 2020 18:54:19 +0200
From:   Peter Zijlstra <peterz@...radead.org>
To:     Josh Poimboeuf <jpoimboe@...hat.com>
Cc:     Christoph Hellwig <hch@....de>,
        Randy Dunlap <rdunlap@...radead.org>,
        Andrew Morton <akpm@...ux-foundation.org>, broonie@...nel.org,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-mm@...ck.org, linux-next@...r.kernel.org, mhocko@...e.cz,
        mm-commits@...r.kernel.org, sfr@...b.auug.org.au,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        viro@...iv.linux.org.uk, x86@...nel.org,
        Steven Rostedt <rostedt@...dmis.org>
Subject: Re: mmotm 2020-05-13-20-30 uploaded (objtool warnings)

On Fri, May 29, 2020 at 11:50:11AM -0500, Josh Poimboeuf wrote:
> The nested likelys seem like overkill anyway -- user_access_begin() is
> __always_inline and it already has unlikely(), which should be
> propagated.
> 
> So just remove the outer likelys?

That fixes it. Ack!

> diff --git a/arch/x86/lib/csum-wrappers_64.c b/arch/x86/lib/csum-wrappers_64.c
> index a12b8629206d..ee63d7576fd2 100644
> --- a/arch/x86/lib/csum-wrappers_64.c
> +++ b/arch/x86/lib/csum-wrappers_64.c
> @@ -27,7 +27,7 @@ csum_and_copy_from_user(const void __user *src, void *dst,
>  	might_sleep();
>  	*errp = 0;
>  
> -	if (!likely(user_access_begin(src, len)))
> +	if (!user_access_begin(src, len))
>  		goto out_err;
>  
>  	/*
> @@ -89,7 +89,7 @@ csum_and_copy_to_user(const void *src, void __user *dst,
>  
>  	might_sleep();
>  
> -	if (unlikely(!user_access_begin(dst, len))) {
> +	if (!user_access_begin(dst, len)) {
>  		*errp = -EFAULT;
>  		return 0;
>  	}
>