From: Martin Lau <kafai@fb.com>
To: Yonghong Song <yhs@fb.com>
Cc: "bpf@vger.kernel.org" <bpf@vger.kernel.org>,
Alexei Starovoitov <ast@kernel.org>,
Daniel Borkmann <daniel@iogearbox.net>,
David Miller <davem@davemloft.net>,
Kernel Team <Kernel-team@fb.com>,
"netdev@vger.kernel.org" <netdev@vger.kernel.org>
Subject: Re: [PATCH bpf-next 06/13] bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS
Date: Fri, 20 Dec 2019 16:52:03 +0000 [thread overview]
Message-ID: <20191220165158.bc6mp7w5ooof262h@kafai-mbp> (raw)
In-Reply-To: <20191220072150.flfxsix4s6jndswn@kafai-mbp>
On Thu, Dec 19, 2019 at 11:22:17PM -0800, Martin Lau wrote:
> [ ... ]
>
> > > +/* __bpf_##_name (e.g. __bpf_tcp_congestion_ops) is the map's value
> > > + * exposed to the userspace and its btf-type-id is stored
> > > + * at the map->btf_vmlinux_value_type_id.
> > > + *
> > > + * The *_name##_dummy is to ensure the BTF type is emitted.
> > > + */
> > > +
> > > #define BPF_STRUCT_OPS_TYPE(_name) \
> > > -extern struct bpf_struct_ops bpf_##_name;
> > > +extern struct bpf_struct_ops bpf_##_name; \
> > > + \
> > > +static struct __bpf_##_name { \
> > > + BPF_STRUCT_OPS_COMMON_VALUE; \
> > > + struct _name data ____cacheline_aligned_in_smp; \
> > > +} *_name##_dummy;
> >
> > There are other ways to retain types in debug info without
> > creating new variables. For example, you can use it in a cast
> > like
> > (void *)(struct __bpf_##_name *)v
> hmm... What is v?
Got it. "v" could be any dummy pointer in a function.
I will use (void) instead of (void *) to avoid compiler warning.
>
> > Not sure whether we could easily find a place for such casting or not.
This can be done in bpf_struct_ops_init().
Thanks for the tips!
next prev parent reply other threads:[~2019-12-20 16:52 UTC|newest]
Thread overview: 51+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-12-14 0:47 [PATCH bpf-next 00/13] Introduce BPF STRUCT_OPS Martin KaFai Lau
2019-12-14 0:47 ` [PATCH bpf-next 01/13] bpf: Save PTR_TO_BTF_ID register state when spilling to stack Martin KaFai Lau
2019-12-16 19:48 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 02/13] bpf: Avoid storing modifier to info->btf_id Martin KaFai Lau
2019-12-16 21:34 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 03/13] bpf: Add enum support to btf_ctx_access() Martin KaFai Lau
2019-12-16 21:36 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 04/13] bpf: Support bitfield read access in btf_struct_access Martin KaFai Lau
2019-12-16 22:05 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 05/13] bpf: Introduce BPF_PROG_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-17 6:14 ` Yonghong Song
2019-12-18 16:41 ` Martin Lau
2019-12-14 0:47 ` [PATCH bpf-next 06/13] bpf: Introduce BPF_MAP_TYPE_STRUCT_OPS Martin KaFai Lau
2019-12-17 7:48 ` [Potential Spoof] " Yonghong Song
2019-12-20 7:22 ` Martin Lau
2019-12-20 16:52 ` Martin Lau [this message]
2019-12-20 18:41 ` Andrii Nakryiko
2019-12-14 0:47 ` [PATCH bpf-next 07/13] bpf: tcp: Support tcp_congestion_ops in bpf Martin KaFai Lau
2019-12-17 17:36 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 08/13] bpf: Add BPF_FUNC_tcp_send_ack helper Martin KaFai Lau
2019-12-17 17:41 ` Yonghong Song
2019-12-14 0:47 ` [PATCH bpf-next 09/13] bpf: Add BPF_FUNC_jiffies Martin KaFai Lau
2019-12-14 1:59 ` Eric Dumazet
2019-12-14 19:25 ` Neal Cardwell
2019-12-16 19:30 ` Martin Lau
2019-12-17 8:26 ` Jakub Sitnicki
2019-12-17 18:22 ` Martin Lau
2019-12-17 21:04 ` Eric Dumazet
2019-12-18 9:03 ` Jakub Sitnicki
2019-12-16 19:14 ` Martin Lau
2019-12-16 19:33 ` Eric Dumazet
2019-12-16 21:17 ` Martin Lau
2019-12-16 23:08 ` Alexei Starovoitov
2019-12-17 0:34 ` Eric Dumazet
2019-12-14 0:48 ` [PATCH bpf-next 10/13] bpf: Synch uapi bpf.h to tools/ Martin KaFai Lau
2019-12-14 0:48 ` [PATCH bpf-next 11/13] bpf: libbpf: Add STRUCT_OPS support Martin KaFai Lau
2019-12-18 3:07 ` Andrii Nakryiko
2019-12-18 7:03 ` Martin Lau
2019-12-18 7:20 ` Martin Lau
2019-12-18 16:36 ` Andrii Nakryiko
2019-12-18 16:34 ` Andrii Nakryiko
2019-12-18 17:33 ` Martin Lau
2019-12-18 18:14 ` Andrii Nakryiko
2019-12-18 20:19 ` Martin Lau
2019-12-19 8:53 ` Toke Høiland-Jørgensen
2019-12-19 20:49 ` Andrii Nakryiko
2019-12-20 10:16 ` Toke Høiland-Jørgensen
2019-12-20 17:34 ` Andrii Nakryiko
2019-12-14 0:48 ` [PATCH bpf-next 12/13] bpf: Add bpf_dctcp example Martin KaFai Lau
2019-12-14 0:48 ` [PATCH bpf-next 13/13] bpf: Add bpf_cubic example Martin KaFai Lau
2019-12-14 2:26 ` [PATCH bpf-next 00/13] Introduce BPF STRUCT_OPS Eric Dumazet
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