linux-kernel - Re: [PATCH bpf-next v6 1/7] bpf: Renames to prepare for generalizing sk

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Date:   Thu, 23 Jul 2020 22:31:35 -0700
From:   Martin KaFai Lau <kafai@...com>
To:     KP Singh <kpsingh@...omium.org>
CC:     <linux-kernel@...r.kernel.org>, <bpf@...r.kernel.org>,
        <linux-security-module@...r.kernel.org>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>,
        Paul Turner <pjt@...gle.com>, Jann Horn <jannh@...gle.com>,
        Florent Revest <revest@...omium.org>
Subject: Re: [PATCH bpf-next v6 1/7] bpf: Renames to prepare for generalizing
 sk_storage.

On Thu, Jul 23, 2020 at 01:50:26PM +0200, KP Singh wrote:
> From: KP Singh <kpsingh@...gle.com>
> 
> A purely mechanical change to split the renaming from the actual
> generalization.
> 
> Flags/consts:
> 
>   SK_STORAGE_CREATE_FLAG_MASK	BPF_LOCAL_STORAGE_CREATE_FLAG_MASK
>   BPF_SK_STORAGE_CACHE_SIZE	BPF_LOCAL_STORAGE_CACHE_SIZE
>   MAX_VALUE_SIZE		BPF_LOCAL_STORAGE_MAX_VALUE_SIZE
> 
> Structs:
> 
>   bucket			bpf_local_storage_map_bucket
>   bpf_sk_storage_map		bpf_local_storage_map
>   bpf_sk_storage_data		bpf_local_storage_data
>   bpf_sk_storage_elem		bpf_local_storage_elem
>   bpf_sk_storage		bpf_local_storage
>   selem_linked_to_sk		selem_linked_to_storage
>   selem_alloc			bpf_selem_alloc
> 
> The "sk" member in bpf_local_storage is also updated to "owner"
> in preparation for changing the type to void * in a subsequent patch.
> 
> Functions:
> 
>   __selem_unlink_sk			bpf_selem_unlink_storage
>   __selem_link_sk			bpf_selem_link_storage
>   selem_unlink_sk			__bpf_selem_unlink_storage
>   sk_storage_update			bpf_local_storage_update
>   __sk_storage_lookup			bpf_local_storage_lookup
>   bpf_sk_storage_map_free		bpf_local_storage_map_free
>   bpf_sk_storage_map_alloc		bpf_local_storage_map_alloc
>   bpf_sk_storage_map_alloc_check	bpf_local_storage_map_alloc_check
>   bpf_sk_storage_map_check_btf		bpf_local_storage_map_check_btf
Thanks for separating this mechanical name change in a separate patch.
It is much easier to follow.  This patch looks good.

A minor thought is, when I look at unlink_map() and unlink_storage(),
it keeps me looking back for the lock situation.  I think
the main reason is the bpf_selem_unlink_map() is locked but
bpf_selem_unlink_storage() is unlocked now.  May be:

bpf_selem_unlink_map()		=> bpf_selem_unlink_map_locked()
bpf_selem_link_map()		=> bpf_selem_link_map_locked()
__bpf_selem_unlink_storage() 	=> bpf_selem_unlink_storage_locked()
bpf_link_storage() means unlocked
bpf_unlink_storage() means unlocked.

I think it could be one follow-up patch later instead of interrupting
multiple patches in this set for this minor thing.  For now, lets
continue with this and remember default is nolock for storage.

I will continue tomorrow.