linux-kernel - Re: [PATCH v3 09/15] perf: Reflow to get rid of aux

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Message-ID: <653d4d30-eaf7-4dbf-8e35-6820996ca491@lucifer.local>
Date: Wed, 13 Aug 2025 07:03:01 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: Peter Zijlstra <peterz@...radead.org>
Cc: tglx@...utronix.de, linux-kernel@...r.kernel.org,
        torvalds@...uxfoundation.org, mingo@...nel.org, namhyung@...nel.org,
        acme@...hat.com, kees@...nel.org
Subject: Re: [PATCH v3 09/15] perf: Reflow to get rid of aux_success label

On Tue, Aug 12, 2025 at 12:39:07PM +0200, Peter Zijlstra wrote:
> Mostly re-indent noise needed to get rid of that label.
>
> Signed-off-by: Peter Zijlstra (Intel) <peterz@...radead.org>

This is where a side-by-side git diff pager comes in handy :)

LGTM apart from nit/comment below so:

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  kernel/events/core.c |   37 ++++++++++++++++++-------------------
>  1 file changed, 18 insertions(+), 19 deletions(-)
>
> --- a/kernel/events/core.c
> +++ b/kernel/events/core.c
> @@ -7127,30 +7127,29 @@ static int perf_mmap(struct file *file,
>  		if (rb_has_aux(rb)) {
>  			atomic_inc(&rb->aux_mmap_count);
>  			ret = 0;
> -			goto aux_success;
> -		}
>
> -		if (!perf_mmap_calc_limits(vma, &user_extra, &extra)) {
> -			ret = -EPERM;
> -			atomic_dec(&rb->mmap_count);
> -			goto unlock;
> -		}

NIT: These leaves  a space above:

		if (rb_has_aux(rb)) {
			atomic_inc(&rb->aux_mmap_count);
			ret = 0;

		} else {


> +		} else {
> +			if (!perf_mmap_calc_limits(vma, &user_extra, &extra)) {
> +				ret = -EPERM;
> +				atomic_dec(&rb->mmap_count);
> +				goto unlock;
> +			}
>
> -		WARN_ON(!rb && event->rb);
> +			WARN_ON(!rb && event->rb);
>
> -		if (vma->vm_flags & VM_WRITE)
> -			flags |= RING_BUFFER_WRITABLE;
> +			if (vma->vm_flags & VM_WRITE)
> +				flags |= RING_BUFFER_WRITABLE;
>
> -		ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
> -				   event->attr.aux_watermark, flags);
> -		if (ret) {
> -			atomic_dec(&rb->mmap_count);
> -			goto unlock;
> -		}
> +			ret = rb_alloc_aux(rb, event, vma->vm_pgoff, nr_pages,
> +					   event->attr.aux_watermark, flags);
> +			if (ret) {
> +				atomic_dec(&rb->mmap_count);
> +				goto unlock;
> +			}
>
> -		atomic_set(&rb->aux_mmap_count, 1);
> -		rb->aux_mmap_locked = extra;
> -aux_success:
> +			atomic_set(&rb->aux_mmap_count, 1);
> +			rb->aux_mmap_locked = extra;
> +		}

This gets rid of the label but leave spretty horrid nesting, but I'm
guessing further refactorings will tame it.

>  		perf_mmap_account(vma, user_extra, extra);
>  		atomic_inc(&event->mmap_count);
>  	}
>
>