netdev - Re: [PATCH bpf-next v11 10/12] selftests/bpf: add testcases for fsession

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Message-ID: <12822324.O9o76ZdvQC@7940hx>
Date: Fri, 23 Jan 2026 16:05:43 +0800
From: Menglong Dong <menglong.dong@...ux.dev>
To: menglong8.dong@...il.com, andrii@...nel.org, bot+bpf-ci@...nel.org
Cc: daniel@...earbox.net, martin.lau@...ux.dev, eddyz87@...il.com,
 song@...nel.org, yonghong.song@...ux.dev, john.fastabend@...il.com,
 kpsingh@...nel.org, sdf@...ichev.me, haoluo@...gle.com, jolsa@...nel.org,
 davem@...emloft.net, dsahern@...nel.org, tglx@...utronix.de,
 mingo@...hat.com, jiang.biao@...ux.dev, bp@...en8.de,
 dave.hansen@...ux.intel.com, x86@...nel.org, hpa@...or.com,
 bpf@...r.kernel.org, netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
 ast@...nel.org, andrii@...nel.org, daniel@...earbox.net,
 martin.lau@...nel.org, eddyz87@...il.com, yonghong.song@...ux.dev,
 clm@...a.com, ihor.solodrai@...ux.dev
Subject:
 Re: [PATCH bpf-next v11 10/12] selftests/bpf: add testcases for fsession

On 2026/1/23 15:57 bot+bpf-ci@...nel.org write:
> > diff --git a/tools/testing/selftests/bpf/progs/fsession_test.c b/tools/testing/selftests/bpf/progs/fsession_test.c
> > new file mode 100644
> > index 000000000000..f504984d42f2
> > --- /dev/null
> > +++ b/tools/testing/selftests/bpf/progs/fsession_test.c
> > @@ -0,0 +1,110 @@
> > +// SPDX-License-Identifier: GPL-2.0
> > +/* Copyright (c) 2025 ChinaTelecom */
> > +#include <vmlinux.h>
> > +#include <bpf/bpf_helpers.h>
> > +#include <bpf/bpf_tracing.h>
> > +
> > +char _license[] SEC("license") = "GPL";
> 
> [ ... ]
> 
> > +__u64 test6_entry_result = 0;
> > +__u64 test6_exit_result = 0;
> > +SEC("fsession/bpf_fentry_test1")
> > +int BPF_PROG(test6, int a)
> > +{
> > +	__u64 addr = bpf_get_func_ip(ctx);
> > +
> > +	if (bpf_session_is_return(ctx))
> > +		test6_exit_result = (const void *) addr == &bpf_fentry_test1;
> > +	else
> > +		test6_entry_result = (const void *) addr == &bpf_fentry_test1;
>                                                           ^^^^^^^^^^^^^^^^^^
> 
> Is the bpf_fentry_test1 symbol declared somewhere? The code references
> &bpf_fentry_test1 but there is no extern declaration with __ksym in this
> file.

The symbol "bpf_fentry_test1" will be declared in vmlinux.h, which is
generated automatically.

> 
> Other BPF selftests that take addresses of kernel symbols declare them
> explicitly, for example get_func_ip_test.c has:
> 
>     extern int bpf_fentry_test1(int a) __ksym;
> 
> And kprobe_multi_session.c has:
> 
>     extern const void bpf_fentry_test1 __ksym;
> 
> Without a similar declaration, will this BPF program compile and load
> correctly?

As I said above, it won't cause compile problem.

Thanks!
Menglong Dong

> 
> > +	return 0;
> > +}
> 
> 
> ---
> AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
> See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md
> 
> CI run summary: https://github.com/kernel-patches/bpf/actions/runs/21278745581
>