From nobody Tue Feb 10 08:27:22 2026 Received: from smtp-relay-internal-1.canonical.com (smtp-relay-internal-1.canonical.com [185.125.188.123]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 96FF61D52B for ; Fri, 5 Apr 2024 22:36:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=185.125.188.123 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712356577; cv=none; b=QhnEztVBmtscBG651y84K4tVh0ckA0hyfDYyC+uzPnbuYX0bX7H/c0v+4vUNELUtHDvLhuLOPdqdZGSZSt5atbNczvjcCqpBq0/3ht5r90eE90qEKKV7FRplAXtixV5tG4ctP8Y2MGqHkVBV0aOlaVs2lW9Gq3Z5yIllSbLVuZc= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1712356577; c=relaxed/simple; bh=a78vMWglkqZNxVpizm3bz2mABJk4IrXHntVwOv9hkR0=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=cvs8cG9FuRdpDp+V8teEn2nH0cw01m2EeiNuWaXqpMYrAdpiOnYNMI9EyA/JOk5lxFS9DaT73Yjs4uPsJs0qjXXIBwCrnLgx9KwTW5yqADVMZOvdVYU0Nrz5BWFwpTT5gWWaHr7Ddvd0113PZiaadHErajolSEjuHe7yh/UD7Pg= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=canonical.com; spf=pass smtp.mailfrom=canonical.com; dkim=pass (2048-bit key) header.d=canonical.com header.i=@canonical.com header.b=W8hVtIXj; arc=none smtp.client-ip=185.125.188.123 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=canonical.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=canonical.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=canonical.com header.i=@canonical.com header.b="W8hVtIXj" Received: from mail-lj1-f197.google.com (mail-lj1-f197.google.com [209.85.208.197]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by smtp-relay-internal-1.canonical.com (Postfix) with ESMTPS id A7A5A3FE51 for ; Fri, 5 Apr 2024 22:36:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=canonical.com; s=20210705; t=1712356564; bh=U9JiGxHu1Zu7lOUTn6nQmFFrRqhFXaTmBwUIearvaJY=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=W8hVtIXjFuDUvmiKWhDbjnGt6i0qTw3PUA5gvOBYeLP8BIiCGs2UJKsS6kdppHUWn Fdmf1HeKJyyjenD1xw5yaLl5BNQKbfGMQe4McwRN28YSXew3Y1aAR259b6CbJ+cA5J FKVoSLp9Gv9FuapotJwwl8h5u+P828WkWTHHSGYWoX46Tn5jgG+Tjw65xR/9W+XYtW 34otTcv/sRrzCoA6zTvv14dadVG1YOZq+K7hJIdAgUnpLkpBg1dAi67ilxvrlfKGI2 BmKIphP+iYx2xNZDsDznppIyuNxHKIxqwOWqI2NKMbebXTh02HT8TRbQrQokEWqqrT BFAr27G3n/N/Q== Received: by mail-lj1-f197.google.com with SMTP id 38308e7fff4ca-2d86005189eso19155931fa.1 for ; Fri, 05 Apr 2024 15:36:04 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712356562; x=1712961362; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=U9JiGxHu1Zu7lOUTn6nQmFFrRqhFXaTmBwUIearvaJY=; b=m1y4IyJl2m0E/dfkvKrQCuPR1s9ffDEkoAqlcDrUGkvkuSZhaF4qosoTWrnZD72Lc9 sXZV+e84d0ZcSjN+QE3nwglaysd+ErhvV6srF8VlfFdgs1uFpJi5wyNdT78UifLuZcRe RdoCr/vMLNDZpTNJb3u+30jegMmenA4YCZSQCvTMV9B3NBgmQTp3ZqVlzIdazi0+xDPD l1NwkSadNQkZmiijAIun3VtR7URxuO4z0m7tZu2OOYzZQZqARULu1iA5eZPK5+nqXV+y 2NSw2HXnNqFrVeRhT/lGOTcC290fxEt9dtmhPSHneiS5gezJTwh9v0TgGmPNtf3INQUS 9+DQ== X-Forwarded-Encrypted: i=1; AJvYcCWTP3/tMZ4BaLNDwz5GgzqMlmzj5bAX3yr7jMMdUWePldS0cg7XAsBeUShp+ZkX9IseKaoNxMk2GALU02wSGkcnVaUb0Y3aFjcD3o+o X-Gm-Message-State: AOJu0YxeFJQYgKBw/1s/MpYhCzNn79GqdsjVD41+lSsfuqa3pQnCtZg5 8cAhq7YdY0cS1DE0wIsR9KxUhWGmIl+5PLCjPOiUOwauqUR+TInmB4yf/DE8jqDU37h72+e9C+r 0fUxlNoGY6yONKIzYnZDfPQShXfaTF6sP7R6m1oaaClw6MGvF+dPFrL5bcXI9cpZua4ArpXQh9Y 3oIg== X-Received: by 2002:a2e:7210:0:b0:2d8:6561:72ca with SMTP id n16-20020a2e7210000000b002d8656172camr1995338ljc.19.1712356562457; Fri, 05 Apr 2024 15:36:02 -0700 (PDT) X-Google-Smtp-Source: AGHT+IGBVMYT18cPC1QCrh2MWjzCOnxzSsVoLjeD9J9cFM+sm3A78FEmzC3KWLy5fGTZ57Qk1PyOaA== X-Received: by 2002:a2e:7210:0:b0:2d8:6561:72ca with SMTP id n16-20020a2e7210000000b002d8656172camr1995321ljc.19.1712356561922; Fri, 05 Apr 2024 15:36:01 -0700 (PDT) Received: from gpd.station (net-2-39-142-110.cust.vodafonedsl.it. [2.39.142.110]) by smtp.gmail.com with ESMTPSA id bi21-20020a05600c3d9500b004163334df40sm1475698wmb.19.2024.04.05.15.36.00 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Apr 2024 15:36:01 -0700 (PDT) From: Andrea Righi To: Andrii Nakryiko , Eduard Zingerman Cc: Alexei Starovoitov , Daniel Borkmann , Martin KaFai Lau , Song Liu , Yonghong Song , John Fastabend , KP Singh , Stanislav Fomichev , Hao Luo , Jiri Olsa , David Vernet , Tejun Heo , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH v3 1/2] libbpf: ringbuf: allow to consume up to a certain amount of items Date: Sat, 6 Apr 2024 00:16:04 +0200 Message-ID: <20240405223556.11142-2-andrea.righi@canonical.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20240405223556.11142-1-andrea.righi@canonical.com> References: <20240405223556.11142-1-andrea.righi@canonical.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" In some cases, instead of always consuming all items from ring buffers in a greedy way, we may want to consume up to a certain amount of items, for example when we need to copy items from the BPF ring buffer to a limited user buffer. This change allows to set an upper limit to the amount of items consumed from one or more ring buffers. Signed-off-by: Andrea Righi --- tools/lib/bpf/ringbuf.c | 23 +++++++++++++++-------- 1 file changed, 15 insertions(+), 8 deletions(-) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index aacb64278a01..2c4031168413 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -231,7 +231,7 @@ static inline int roundup_len(__u32 len) return (len + 7) / 8 * 8; } =20 -static int64_t ringbuf_process_ring(struct ring *r) +static int64_t ringbuf_process_ring(struct ring *r, size_t n) { int *len_ptr, len, err; /* 64-bit to avoid overflow in case of extreme application behavior */ @@ -268,6 +268,9 @@ static int64_t ringbuf_process_ring(struct ring *r) } =20 smp_store_release(r->consumer_pos, cons_pos); + + if (cnt >=3D n) + goto done; } } while (got_new_data); done: @@ -287,13 +290,15 @@ int ring_buffer__consume(struct ring_buffer *rb) for (i =3D 0; i < rb->ring_cnt; i++) { struct ring *ring =3D rb->rings[i]; =20 - err =3D ringbuf_process_ring(ring); + err =3D ringbuf_process_ring(ring, INT_MAX); if (err < 0) return libbpf_err(err); res +=3D err; + if (res > INT_MAX) { + res =3D INT_MAX; + break; + } } - if (res > INT_MAX) - return INT_MAX; return res; } =20 @@ -314,13 +319,15 @@ int ring_buffer__poll(struct ring_buffer *rb, int tim= eout_ms) __u32 ring_id =3D rb->events[i].data.fd; struct ring *ring =3D rb->rings[ring_id]; =20 - err =3D ringbuf_process_ring(ring); + err =3D ringbuf_process_ring(ring, INT_MAX); if (err < 0) return libbpf_err(err); res +=3D err; + if (res > INT_MAX) { + res =3D INT_MAX; + break; + } } - if (res > INT_MAX) - return INT_MAX; return res; } =20 @@ -375,7 +382,7 @@ int ring__consume(struct ring *r) { int64_t res; =20 - res =3D ringbuf_process_ring(r); + res =3D ringbuf_process_ring(r, INT_MAX); if (res < 0) return libbpf_err(res); =20 --=20 2.43.0