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From: sashiko-bot@kernel.org
To: "Jay Wang" <wanjay@amazon.com>
Cc: gary@garyguo.net, bpf@vger.kernel.org,
	linux-input@vger.kernel.org, sched-ext@lists.linux.dev,
	ojeda@kernel.org, linux-trace-kernel@vger.kernel.org,
	linux-modules@vger.kernel.org, "Petr Pavlu" <petr.pavlu@suse.com>,
	dmitry.torokhov@gmail.com, linux-perf-users@vger.kernel.org
Subject: Re: [PATCH bpf-next v4 06/12] bpf: defer vmlinux kfunc and struct_ops registrations
Date: Fri, 02 Oct 2026 09:14:10 +0000	[thread overview]
Message-ID: <20261002091410.729531F00893@smtp.kernel.org> (raw)
In-Reply-To: <20261001225214.12351-7-wanjay@amazon.com>

> With CONFIG_DEBUG_INFO_BTF=m the vmlinux BTF is loaded on first use.  For
> that to save anything, nothing may pull it in at boot.  The verifier no
> longer does since the previous patches, but register_btf_kfunc_id_set(),
> register_btf_id_dtor_kfuncs() and register_bpf_struct_ops() for vmlinux
> run from initcalls and need the parsed BTF.
> 
> Queue them instead (btf_defer_reg()) and apply them in
> btf_parse_vmlinux(), before the BTF is published, so that no program can
> see a vmlinux BTF without its kfuncs and struct_ops, not even by id: the
> id is reserved before the queue is applied, so that nothing can fail once
> it is, and installed afterwards (btf_reserve_id(), btf_install_id()).
> Applying a struct_ops runs its ->init(), which registers the kfunc sets
> of its hook; those land back on the queue, so it is drained in a loop
> until a pass adds nothing, and only then are new registrations applied
> directly.  The dtor arrays are copied: every caller in the tree builds
> [ ... ]
> together with deferring the module BTF itself.  With =y the BTF is
> present from boot and nothing is queued.  Nothing here is reachable
> until the Kconfig symbol becomes a tristate.
> 
> Signed-off-by: Jay Wang <wanjay@amazon.com>

Sashiko has reviewed this patch and found no issues. It looks great!

-- 
Sashiko AI review · https://sashiko.dev/#/patchset/20261001225214.12351-1-wanjay@amazon.com?part=6


  reply	other threads:[~2026-10-02  9:14 UTC|newest]

Thread overview: 41+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-10-01 22:52 [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory Jay Wang
2026-10-01 22:52 ` [PATCH bpf-next v4 01/12] bpf: pass the vmlinux BTF to btf_parse_module() and let it adopt the data Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 02/12] bpf: split the kfunc, dtor kfunc and struct_ops registration bodies Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 03/12] bpf: fetch the vmlinux BTF where kernel types enter a program Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 04/12] bpf: take the vmlinux BTF from the btf_vmlinux module Jay Wang
2026-10-01 23:45   ` bot+bpf-ci
2026-10-02  9:14   ` sashiko-bot
2026-10-02 11:48   ` Alexei Starovoitov
2026-10-01 22:52 ` [PATCH bpf-next v4 05/12] bpf, tracing: load the vmlinux BTF where tracefs and bpffs requests start Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 06/12] bpf: defer vmlinux kfunc and struct_ops registrations Jay Wang
2026-10-02  9:14   ` sashiko-bot [this message]
2026-10-01 22:52 ` [PATCH bpf-next v4 07/12] bpf: keep module BTF until the vmlinux BTF is available Jay Wang
2026-10-01 23:45   ` bot+bpf-ci
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 08/12] bpf: expose deferred .BTF.base module BTF in sysfs from module load Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 09/12] bpf, trace, net: prepare CONFIG_DEBUG_INFO_BTF checks for a tristate Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-05 11:32   ` Nicolas Schier
2026-10-01 22:52 ` [PATCH bpf-next v4 10/12] resolve_btfids: add --btf_link to fill in .BTF.link records Jay Wang
2026-10-01 23:29   ` bot+bpf-ci
2026-10-02  9:14   ` sashiko-bot
2026-10-01 22:52 ` [PATCH bpf-next v4 11/12] tools, samples: take the vmlinux BTF from vmlinux.unstripped first Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-05 11:17   ` Nicolas Schier
2026-10-01 22:52 ` [PATCH bpf-next v4 12/12] kbuild, bpf: allow building the vmlinux BTF as a module Jay Wang
2026-10-02  9:14   ` sashiko-bot
2026-10-02  9:47   ` Alan Maguire
2026-10-02  4:36 ` [PATCH bpf-next v4 00/12] bpf: make the vmlinux BTF an on-demand loadable module (CONFIG_DEBUG_INFO_BTF=m) to save ~5.4 MB memory Ihor Solodrai
2026-10-02  7:34   ` Jay Wang
2026-10-02 10:05     ` Alan Maguire
2026-10-02 20:58     ` Ihor Solodrai
2026-10-03  6:38       ` Alexei Starovoitov
2026-10-03 11:45         ` Alan Maguire
2026-10-03 12:19           ` Alexei Starovoitov
2026-10-04 22:21       ` Jay Wang
2026-10-05 19:01         ` Ihor Solodrai

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