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Thu, 05 Mar 2026 09:37:15 -0800 (PST) Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset=UTF-8 Date: Thu, 05 Mar 2026 12:37:14 -0500 Message-Id: Cc: , , , , , , Subject: Re: [PATCH bpf-next v3 2/2] bpf: Add deep call stack selftests From: "Emil Tsalapatis" To: "Eduard Zingerman" , X-Mailer: aerc 0.20.1 References: <20260303043106.406099-1-emil@etsalapatis.com> <20260303043106.406099-3-emil@etsalapatis.com> In-Reply-To: On Tue Mar 3, 2026 at 8:15 PM EST, Eduard Zingerman wrote: > On Mon, 2026-03-02 at 23:31 -0500, Emil Tsalapatis wrote: >> Add tests that demonstrate the verifier support for deep call stacks >> while still enforcing maximum stack size limits. >>=20 >> Signed-off-by: Emil Tsalapatis >> --- > > Acked-by: Eduard Zingerman > > [...] > >> +/* Check we actually honor stack limits (33 * 16 =3D 528 > 512 =3D MAX_= STACK_DEPTH). */ > > Nit: I was wondering why stack usage per func is 16, as each one only > consumes one slot. Turns out round_up_stack_depth() rounds things > up to 16. Could you please either add a comment here, or just add > a second long in each function? > Ack, I will clarify why this is the case in a comment. >> +SEC("syscall") >> +__failure __msg("combined stack size of 34 calls") >> +int global_func_deep_stack_fail(struct __sk_buff *skb) >> +{ >> + return f32(123); >> +}