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From: Jakub Sitnicki <jakub@cloudflare.com>
To: Lorenz Bauer <lmb@cloudflare.com>
Cc: Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	kernel-team@cloudflare.com, netdev@vger.kernel.org,
	bpf@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 2/5] bpf: convert queue and stack map to map_copy_value
Date: Wed, 11 Mar 2020 15:00:57 +0100	[thread overview]
Message-ID: <87tv2vxa7a.fsf@cloudflare.com> (raw)
In-Reply-To: <20200310174711.7490-3-lmb@cloudflare.com>

On Tue, Mar 10, 2020 at 06:47 PM CET, Lorenz Bauer wrote:
> Migrate BPF_MAP_TYPE_QUEUE and BPF_MAP_TYPE_STACK to map_copy_value,
> by introducing small wrappers that discard the (unused) key argument.
>
> Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
> ---
>  kernel/bpf/queue_stack_maps.c | 18 ++++++++++++++++++
>  kernel/bpf/syscall.c          |  5 +----
>  2 files changed, 19 insertions(+), 4 deletions(-)
>
> diff --git a/kernel/bpf/queue_stack_maps.c b/kernel/bpf/queue_stack_maps.c
> index f697647ceb54..5c89b7583cd2 100644
> --- a/kernel/bpf/queue_stack_maps.c
> +++ b/kernel/bpf/queue_stack_maps.c
> @@ -262,11 +262,28 @@ static int queue_stack_map_get_next_key(struct bpf_map *map, void *key,
>  	return -EINVAL;
>  }
>
> +/* Called from syscall */
> +static int queue_map_copy_value(struct bpf_map *map, void *key, void *value)
> +{
> +	(void)key;

Alternatively, there's is the __always_unused compiler attribute from
include/linux/compiler_attributes.h that seems to be in wide use.

> +
> +	return queue_map_peek_elem(map, value);
> +}
> +
> +/* Called from syscall */
> +static int stack_map_copy_value(struct bpf_map *map, void *key, void *value)
> +{
> +	(void)key;
> +
> +	return stack_map_peek_elem(map, value);
> +}
> +
>  const struct bpf_map_ops queue_map_ops = {
>  	.map_alloc_check = queue_stack_map_alloc_check,
>  	.map_alloc = queue_stack_map_alloc,
>  	.map_free = queue_stack_map_free,
>  	.map_lookup_elem = queue_stack_map_lookup_elem,
> +	.map_copy_value = queue_map_copy_value,
>  	.map_update_elem = queue_stack_map_update_elem,
>  	.map_delete_elem = queue_stack_map_delete_elem,
>  	.map_push_elem = queue_stack_map_push_elem,
> @@ -280,6 +297,7 @@ const struct bpf_map_ops stack_map_ops = {
>  	.map_alloc = queue_stack_map_alloc,
>  	.map_free = queue_stack_map_free,
>  	.map_lookup_elem = queue_stack_map_lookup_elem,
> +	.map_copy_value = stack_map_copy_value,
>  	.map_update_elem = queue_stack_map_update_elem,
>  	.map_delete_elem = queue_stack_map_delete_elem,
>  	.map_push_elem = queue_stack_map_push_elem,
> diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
> index 6503824e81e9..20c6cdace275 100644
> --- a/kernel/bpf/syscall.c
> +++ b/kernel/bpf/syscall.c
> @@ -218,10 +218,7 @@ static int bpf_map_copy_value(struct bpf_map *map, void *key, void *value,
>  		return bpf_map_offload_lookup_elem(map, key, value);
>
>  	bpf_disable_instrumentation();
> -	if (map->map_type == BPF_MAP_TYPE_QUEUE ||
> -	    map->map_type == BPF_MAP_TYPE_STACK) {
> -		err = map->ops->map_peek_elem(map, value);
> -	} else if (map->ops->map_copy_value) {
> +	if (map->ops->map_copy_value) {
>  		err = map->ops->map_copy_value(map, key, value);
>  	} else {
>  		rcu_read_lock();

  reply	other threads:[~2020-03-11 14:01 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <20200310174711.7490-1-lmb@cloudflare.com>
2020-03-10 17:47 ` [PATCH 1/5] bpf: add map_copy_value hook Lorenz Bauer
2020-03-10 17:47 ` [PATCH 2/5] bpf: convert queue and stack map to map_copy_value Lorenz Bauer
2020-03-11 14:00   ` Jakub Sitnicki [this message]
2020-03-11 22:31     ` John Fastabend
2020-03-10 17:47 ` [PATCH 3/5] bpf: convert sock map and hash " Lorenz Bauer
2020-03-11 13:55   ` Jakub Sitnicki
2020-03-10 17:47 ` [PATCH 4/5] bpf: sockmap, sockhash: return file descriptors from privileged lookup Lorenz Bauer
2020-03-11 23:27   ` John Fastabend
2020-03-17 10:17     ` Lorenz Bauer
2020-03-17 15:18   ` Jakub Sitnicki
2020-03-17 18:16     ` John Fastabend
2020-03-10 17:47 ` [PATCH 5/5] bpf: sockmap, sockhash: test looking up fds Lorenz Bauer
2020-03-11 13:52   ` Jakub Sitnicki
2020-03-11 17:24     ` Lorenz Bauer

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