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From: Hao Luo <haoluo@google.com>
To: "Daniel Müller" <deso@posteo.net>
Cc: bpf <bpf@vger.kernel.org>, Alexei Starovoitov <ast@kernel.org>,
	Daniel Borkmann <daniel@iogearbox.net>,
	Andrii Nakryiko <andrii@kernel.org>,
	Martin KaFai Lau <martin.lau@linux.dev>,
	Song Liu <song@kernel.org>, Yonghong Song <yhs@fb.com>,
	KP Singh <kpsingh@kernel.org>,
	Stanislav Fomichev <sdf@google.com>, Jiri Olsa <jolsa@kernel.org>,
	John Fastabend <john.fastabend@gmail.com>,
	kernel-team@meta.com
Subject: Re: CORE feature request: support checking field type directly
Date: Tue, 17 Jan 2023 16:55:44 -0800	[thread overview]
Message-ID: <CA+khW7gFq3VKEvF7hZXQsLJagz=HMZ4kJwh=QdmFG1pFbq1xRw@mail.gmail.com> (raw)
In-Reply-To: <20230117222158.uyezr5ab72ck5fhv@muellerd-fedora-PC2BDTX9>

Hi Daniel,

On Tue, Jan 17, 2023 at 2:22 PM Daniel Müller <deso@posteo.net> wrote:
>
> I apologize for the response. Somehow Andrii's reply and the entire thread was
> lost on me. Anyway, glad it's working for you.
>

Andrii helped me get it work. TYPE_MATCHES is a solution to my
problem. Now I have a better understanding on how
bpf_core_type_matches works.

For the record, the following works on my old kernel and new kernels:

struct rw_semaphore___old {
        struct task_struct *owner;
};

struct rw_semaphore___new {
        atomic_long_t owner;
};

u64 owner;
if (bpf_core_type_matches(struct rw_semaphore___old)) { /* owner is
task_struct pointer */
        struct rw_semaphore___old *old = (struct rw_semaphore___old *)sem;
        owner = (u64)sem->owner;
} else if (bpf_core_type_matches(struct rw_semaphore___new)) { /*
owner field is atomic_long_t */
        struct rw_semaphore___new *new = (struct rw_semaphore___new *)sem;
        owner = (u64)new->owner.counter;
}

Thanks for your response!
Hao

  reply	other threads:[~2023-01-18  1:07 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-01-12 22:18 CORE feature request: support checking field type directly Hao Luo
2023-01-13 23:41 ` Andrii Nakryiko
2023-01-14  1:06   ` Hao Luo
2023-01-14  1:14     ` Andrii Nakryiko
2023-01-14  2:19       ` Hao Luo
2023-01-14  2:44         ` Andrii Nakryiko
2023-01-17 18:45           ` Hao Luo
2023-01-17 21:56 ` Daniel Müller
2023-01-17 22:21   ` Daniel Müller
2023-01-18  0:55     ` Hao Luo [this message]
2023-01-31  6:06       ` Namhyung Kim
2023-01-31 16:46         ` Daniel Müller
2023-01-31 19:58           ` Namhyung Kim

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