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Tue, 5 Aug 2025 13:03:50 GMT Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 301902004D; Tue, 5 Aug 2025 13:03:50 +0000 (GMT) Received: from smtpav07.fra02v.mail.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 23A9520040; Tue, 5 Aug 2025 13:03:49 +0000 (GMT) Received: from heavy.ibm.com (unknown [9.87.141.116]) by smtpav07.fra02v.mail.ibm.com (Postfix) with ESMTP; Tue, 5 Aug 2025 13:03:49 +0000 (GMT) From: Ilya Leoshkevich To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Ian Rogers , Arnaldo Carvalho de Melo Cc: bpf@vger.kernel.org, linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org, linux-s390@vger.kernel.org, Thomas Richter , Jiri Olsa , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Ilya Leoshkevich Subject: [PATCH v3 1/2] libbpf: Add the ability to suppress perf event enablement Date: Tue, 5 Aug 2025 14:54:04 +0200 Message-ID: <20250805130346.1225535-2-iii@linux.ibm.com> X-Mailer: git-send-email 2.50.1 In-Reply-To: <20250805130346.1225535-1-iii@linux.ibm.com> References: <20250805130346.1225535-1-iii@linux.ibm.com> Precedence: bulk X-Mailing-List: linux-perf-users@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: MhSFNhiVsLSK11Rjn3lbrUYxrrJs5w7d X-Authority-Analysis: v=2.4 cv=dNummPZb c=1 sm=1 tr=0 ts=6892013b cx=c_pps a=aDMHemPKRhS1OARIsFnwRA==:117 a=aDMHemPKRhS1OARIsFnwRA==:17 a=2OwXVqhp2XgA:10 a=VwQbUJbxAAAA:8 a=VnNF1IyMAAAA:8 a=5Tfx8qovrACkoZmbRlMA:9 X-Proofpoint-ORIG-GUID: TW7xbIt1y1u0HOPmQdlcuS-tZzJlO244 X-Proofpoint-Spam-Details-Enc: AW1haW4tMjUwODA1MDA5MCBTYWx0ZWRfX1W7T1XxXpGvU XDolJo/df3zFzod2G0pUB+iZCySjXFm+njIKXw/RaFBSukDBXHkFmJt/i3mjmBIU52/Yehn8cvd 7YcNsTJhAgcf4DuYVH+faP9stl462+22xFizdQZNaqmgpd+hyr6aRnrwQ+cMoqS0JanRWg9EVnG 9GVa7p6louUJd8n88Q6qWRr4Qsghql9g6q2pAy/j+SrGt4zyHlaR5InziGCvGypy5zhShD5/+ao lpIXGNVBcEfxGsoZVQCH/+GCZkz7UsuvjQlfasE4WW+EPrGdtLhJYtztXQQe3zf4564N0ai+qsF o22PSx1LUdCvLVS8i3f2eHxvnfSb/DyvsvB2DmtmSWG98y3SfjN5S30WDuh+emB6REAvlFGjzLI BfpNmuPdIomNfKhe7/xIXEVyXaPWOEK5mIn+syy0UUB15fIZdVrDVOOmfVC/kNgwGjF3I4/h X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.293,Aquarius:18.0.1099,Hydra:6.1.9,FMLib:17.12.80.40 definitions=2025-08-05_03,2025-08-04_01,2025-03-28_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 phishscore=0 bulkscore=0 mlxscore=0 clxscore=1015 mlxlogscore=902 malwarescore=0 priorityscore=1501 adultscore=0 lowpriorityscore=0 spamscore=0 suspectscore=0 impostorscore=0 classifier=spam authscore=0 authtc=n/a authcc= route=outbound adjust=0 reason=mlx scancount=1 engine=8.19.0-2505280000 definitions=main-2508050090 Automatically enabling a perf event after attaching a BPF prog to it is not always desirable. Add a new no_ioctl_enable field to struct bpf_perf_event_opts. While introducing ioctl_enable instead would be nicer in that it would avoid a double negation in the implementation, it would make DECLARE_LIBBPF_OPTS() less efficient. Suggested-by: Jiri Olsa Co-developed-by: Thomas Richter Signed-off-by: Thomas Richter Signed-off-by: Ilya Leoshkevich --- tools/lib/bpf/libbpf.c | 13 ++++++++----- tools/lib/bpf/libbpf.h | 4 +++- 2 files changed, 11 insertions(+), 6 deletions(-) diff --git a/tools/lib/bpf/libbpf.c b/tools/lib/bpf/libbpf.c index fb4d92c5c339..414c566c4650 100644 --- a/tools/lib/bpf/libbpf.c +++ b/tools/lib/bpf/libbpf.c @@ -10965,11 +10965,14 @@ struct bpf_link *bpf_program__attach_perf_event_opts(const struct bpf_program *p } link->link.fd = pfd; } - if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { - err = -errno; - pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n", - prog->name, pfd, errstr(err)); - goto err_out; + + if (!OPTS_GET(opts, no_ioctl_enable, false)) { + if (ioctl(pfd, PERF_EVENT_IOC_ENABLE, 0) < 0) { + err = -errno; + pr_warn("prog '%s': failed to enable perf_event FD %d: %s\n", + prog->name, pfd, errstr(err)); + goto err_out; + } } return &link->link; diff --git a/tools/lib/bpf/libbpf.h b/tools/lib/bpf/libbpf.h index d1cf813a057b..2d3cc436cdbf 100644 --- a/tools/lib/bpf/libbpf.h +++ b/tools/lib/bpf/libbpf.h @@ -499,9 +499,11 @@ struct bpf_perf_event_opts { __u64 bpf_cookie; /* don't use BPF link when attach BPF program */ bool force_ioctl_attach; + /* don't automatically enable the event */ + bool no_ioctl_enable; size_t :0; }; -#define bpf_perf_event_opts__last_field force_ioctl_attach +#define bpf_perf_event_opts__last_field no_ioctl_enable LIBBPF_API struct bpf_link * bpf_program__attach_perf_event(const struct bpf_program *prog, int pfd); -- 2.50.1