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[52.15.100.147]) by smtp.googlemail.com with ESMTPSA id f10-20020a05620a15aa00b0078d76c1178esm1756677qkk.119.2024.04.11.18.50.55 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 11 Apr 2024 18:50:56 -0700 (PDT) From: Kyle Huey X-Google-Original-From: Kyle Huey To: Kyle Huey , linux-kernel@vger.kernel.org, Andrii Nakryiko , Jiri Olsa , Namhyung Kim , Marco Elver , Yonghong Song , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo Cc: Robert O'Callahan , bpf@vger.kernel.org, Song Liu , Andrii Nakryiko , Ingo Molnar , Mark Rutland , Alexander Shishkin , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org Subject: [PATCH v6 6/7] perf/bpf: Allow a bpf program to suppress all sample side effects Date: Thu, 11 Apr 2024 18:50:18 -0700 Message-Id: <20240412015019.7060-7-khuey@kylehuey.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20240412015019.7060-1-khuey@kylehuey.com> References: <20240412015019.7060-1-khuey@kylehuey.com> Precedence: bulk X-Mailing-List: linux-kernel@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" Returning zero from a bpf program attached to a perf event already suppresses any data output. Return early from __perf_event_overflow() in this case so it will also suppress event_limit accounting, SIGTRAP generation, and F_ASYNC signalling. Signed-off-by: Kyle Huey Acked-by: Song Liu Acked-by: Jiri Olsa Acked-by: Namhyung Kim Acked-by: Andrii Nakryiko --- kernel/events/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index fd601d509cea..cd88d1e89eb8 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9658,6 +9658,9 @@ static int __perf_event_overflow(struct perf_event *e= vent, =20 ret =3D __perf_event_account_interrupt(event, throttle); =20 + if (event->prog && !bpf_overflow_handler(event, data, regs)) + return ret; + /* * XXX event_limit might not quite work as expected on inherited * events @@ -9707,8 +9710,7 @@ static int __perf_event_overflow(struct perf_event *e= vent, irq_work_queue(&event->pending_irq); } =20 - if (!(event->prog && !bpf_overflow_handler(event, data, regs))) - READ_ONCE(event->overflow_handler)(event, data, regs); + READ_ONCE(event->overflow_handler)(event, data, regs); =20 if (*perf_event_fasync(event) && event->pending_kill) { event->pending_wakeup =3D 1; --=20 2.34.1