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[76.126.33.191]) by smtp.gmail.com with ESMTPSA id iw15-20020a170903044f00b001d1cd7e4acfsm6143plb.201.2023.12.07.08.35.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 07 Dec 2023 08:35:11 -0800 (PST) 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 Cc: Robert O'Callahan , Peter Zijlstra , Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Ian Rogers , Adrian Hunter , linux-perf-users@vger.kernel.org Subject: [PATCH v2 1/3] perf: Reorder overflow handler ahead of event_limit/sigtrap Date: Thu, 7 Dec 2023 08:34:56 -0800 Message-Id: <20231207163458.5554-2-khuey@kylehuey.com> X-Mailer: git-send-email 2.34.1 In-Reply-To: <20231207163458.5554-1-khuey@kylehuey.com> References: <20231207163458.5554-1-khuey@kylehuey.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" The perf subsystem already allows an overflow handler to clear pending_kill to suppress a fasync signal (although nobody currently does this). Allow an overflow handler to suppress the other visible side effects of an overflow, namely event_limit accounting and SIGTRAP generation. Signed-off-by: Kyle Huey --- kernel/events/core.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index b704d83a28b2..19fddfc27a4a 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -9541,6 +9541,12 @@ static int __perf_event_overflow(struct perf_event *= event, */ =20 event->pending_kill =3D POLL_IN; + + READ_ONCE(event->overflow_handler)(event, data, regs); + + if (!event->pending_kill) + return ret; + if (events && atomic_dec_and_test(&event->event_limit)) { ret =3D 1; event->pending_kill =3D POLL_HUP; @@ -9584,9 +9590,7 @@ static int __perf_event_overflow(struct perf_event *e= vent, irq_work_queue(&event->pending_irq); } =20 - READ_ONCE(event->overflow_handler)(event, data, regs); - - if (*perf_event_fasync(event) && event->pending_kill) { + if (*perf_event_fasync(event)) { event->pending_wakeup =3D 1; irq_work_queue(&event->pending_irq); } --=20 2.34.1