netdev - Re: [PATCH v2 bpf-next 3/4] bpf: Allow using bpf_sk_storage in FENTRY/FEXIT/RAW

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Message-ID: <20201114171720.50ae0a51@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Sat, 14 Nov 2020 17:17:20 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Martin KaFai Lau <kafai@...com>
Cc:     <bpf@...r.kernel.org>, Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, <kernel-team@...com>,
        <netdev@...r.kernel.org>, Song Liu <songliubraving@...com>
Subject: Re: [PATCH v2 bpf-next 3/4] bpf: Allow using bpf_sk_storage in
 FENTRY/FEXIT/RAW_TP

On Thu, 12 Nov 2020 13:13:13 -0800 Martin KaFai Lau wrote:
> This patch adds bpf_sk_storage_get_tracing_proto and
> bpf_sk_storage_delete_tracing_proto.  They will check
> in runtime that the helpers can only be called when serving
> softirq or running in a task context.  That should enable
> most common tracing use cases on sk.

> +	if (!in_serving_softirq() && !in_task())

This is a curious combination of checks. Would you mind indulging me
with an explanation?