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[192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49807b6093fsm53217885e9.1.2026.08.01.16.15.16 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 01 Aug 2026 16:15:16 -0700 (PDT) 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: Sun, 02 Aug 2026 01:15:16 +0200 Message-Id: From: "Kumar Kartikeya Dwivedi" To: Cc: Subject: Re: [PATCH bpf-next v1 1/3] bpf: Show more useful info in stack depth stats X-Mailer: aerc 0.21.0 References: <20260801230400.850271-1-memxor@gmail.com> <20260801230400.850271-2-memxor@gmail.com> <20260801231113.D0B711F00AC4@smtp.kernel.org> In-Reply-To: <20260801231113.D0B711F00AC4@smtp.kernel.org> On Sun Aug 2, 2026 at 1:11 AM CEST, sashiko-bot wrote: > Thank you for your contribution! Sashiko AI review found 1 potential issu= e(s) to consider: > - [Medium] The new stack depth verifier log format breaks stack metrics p= arsing in the `veristat` tool. > -- > > --- Patch [1]: [PATCH bpf-next v1 1/3] bpf: Show more useful info in stac= k depth stats --- > commit f7cb915ff02de7a02fe7b2353a1f2d77e1852496 > Author: Kumar Kartikeya Dwivedi > > bpf: Show more useful info in stack depth stats > > This commit changes the output format of stack depth statistics in the BP= F > verifier log. It replaces the old subprogram index-based format with a cl= earer > name and depth format, avoiding hard-to-read sequences. > >> diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c >> index 8d0635ee48c7e..51ac0a9ae3394 100644 >> --- a/kernel/bpf/verifier.c >> +++ b/kernel/bpf/verifier.c >> @@ -18703,10 +18703,18 @@ static void print_verification_stats(struct bp= f_verifier_env *env) >> if (env->log.level & BPF_LOG_STATS) { >> verbose(env, "verification time %lld usec\n", >> div_u64(env->verification_time, 1000)); >> - verbose(env, "stack depth %d", env->subprog_info[0].stack_depth); >> - for (i =3D 1; i < subprog_cnt; i++) >> - verbose(env, "+%d", env->subprog_info[i].stack_depth); >> - verbose(env, " max %d\n", env->max_stack_depth); >> + verbose(env, "stack depth"); >> + for (i =3D 0; i < subprog_cnt; i++) { >> + const char *name =3D env->subprog_info[i].name; >> + >> + if (name && name[0]) >> + verbose(env, " %s=3D%d", name, >> + env->subprog_info[i].stack_depth); >> + else >> + verbose(env, " subprog[%d]=3D%d", i, >> + env->subprog_info[i].stack_depth); >> + } >> + verbose(env, " max=3D%d\n", env->max_stack_depth); > > [Severity: Medium] > Does this change break the veristat tool's parsing of stack depths? > > Looking at tools/testing/selftests/bpf/veristat.c in parse_verif_log(), i= t > appears to rely on the old format using a hardcoded string and splitting = by > the plus sign: > > tools/testing/selftests/bpf/veristat.c:parse_verif_log() { > ... > if (2 =3D=3D sscanf(cur, "stack depth %511s max %ld", stack, &s->stat= s[MAX_STACK])) > ... > while ((token =3D strtok_r(cnt++ ? NULL : stack, "+", &state))) { > if (sscanf(token, "%d", &sub_stack) =3D=3D 0) > break; > ... > } > > Since the verifier now outputs max=3D%ld instead of max %ld, and the indi= vidual > depths are formatted as name=3Ddepth rather than numbers separated by a p= lus > sign, will veristat silently fail to parse STACK and MAX_STACK metrics wh= en > processing BPF objects? > Fixed in patch 2. It is an open question whether we care about format compatibility, in that case we will need further adjustments to parse both = kinds of output (for older and newer kernels). > [ ... ]