From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 6C5E114A60F; Fri, 19 Jun 2026 00:27:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781828831; cv=none; b=I7T8AMqg9PDc3RN+4QoBL77xwh1bVcq7sMBOhQbqd18zom6sjK7rgV4btT1p+V0vGdwM7yOR5TTjeSnRnIrUHVuI9z4j/6XpGoK8PiqBNsc6P+GDBWSUfB3UfyOAGYdD/VRaX6YDLXVk/ZD1HQdmDLpVLKE2q6pQVKc+VnWzEzE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1781828831; c=relaxed/simple; bh=CGCb9qRFDcGc9e7ZQq52eEFE9DKiwifqHqT601ICGc0=; h=From:Date:Subject:MIME-Version:Content-Type:Message-Id:References: In-Reply-To:To:Cc; b=XbPuA5Dhq4gnxqvEyRbWOjCm6IlrGWTl/QCjY9l4/VxPzYkUtt6ybX7J2V/vMfwxFaIzVThikV5EpA3BIZjfz58HXcZFB7CMSfOlZqEdwdEqDRTyZg+1CyYjiSHT2bNVCOSbo+3tH6rS7ouKFlmdCRKzbsl1uRp+hQJQkCD57ZI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=BxaDVUf6; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="BxaDVUf6" Received: by smtp.kernel.org (Postfix) with ESMTPSA id B7A061F00A3E; Fri, 19 Jun 2026 00:27:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1781828830; bh=xfz0GJo0N1HOrcsNX3l2q7OqvtWMOnwlcylei6NnLCs=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=BxaDVUf6FAuywyUSm3odWFJQPGCNYCb1W2/sBKqMTSN4nZD/YYiDkRQGa+7pdbRqN 3xd1Anh6rmJrPTYlbicHOdX2qp4qn+3BWrEUHSls5FKqvkKScGXQWdZg55cQFxWXko 0ry39VAtKm5aJWIgQbbvKFXSsYXlDTC1nuqDt3d9KI0riucRsAcHgDZZuok0cCDCyy Uj3H4vkWs4lKmMvoaVDN1LZQhT/78MMLJw0uxMqD85NM5AurCh1FGBTedmpIMcAfXU KKl685LLoUh4LVpbXDdU7WIRNRGtVfdC7zw/DK8GGqFvJae6DcuyREy/o4hA//X58u 5THWdq/ZNOIOQ== From: Tamir Duberstein Date: Thu, 18 Jun 2026 20:26:39 -0400 Subject: [PATCH bpf v2 1/8] libbpf: ringbuf: Honor zero consume bounds Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20260618-bpf-ringbuf-fixes-v2-1-33fde039ddf3@kernel.org> References: <20260618-bpf-ringbuf-fixes-v2-0-33fde039ddf3@kernel.org> In-Reply-To: <20260618-bpf-ringbuf-fixes-v2-0-33fde039ddf3@kernel.org> To: Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Martin KaFai Lau , Eduard Zingerman , Kumar Kartikeya Dwivedi , Song Liu , Yonghong Song , Jiri Olsa , Shuah Khan , Andrea Righi , Xu Kuohai , Andrea Righi , Bing-Jhong Billy Jheng , David Vernet Cc: bpf@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Werner , Zvi Effron , Andrii Nakryiko , Emil Tsalapatis , Tamir Duberstein X-Mailer: b4 0.16-dev X-Developer-Signature: v=1; a=openpgp-sha256; l=2326; i=tamird@kernel.org; h=from:subject:message-id; bh=CGCb9qRFDcGc9e7ZQq52eEFE9DKiwifqHqT601ICGc0=; b=owGbwMvMwCV2wYdPVfy60HTG02pJDFkmPVc3Xrz2WOBYZ/3lR6d9eLg3nLhqVecnG/dAOjWCd 3Lp2++TOiayMIhxMViKKbIkih7am556e49s5rvjMHNYmUCGSIs0MAABCwNfbmJeqZGOkZ6ptqGe oZGOgY4xAxenAEz1sVSG/5XzvgaYffZhES7JdraxZLVVeNFTLHVHOuBP1i4R+ymTLBkZOiY36c7 wtV8tu+Pn563cldsDbxgeCuXiOhdt596uWpbOBgA= X-Developer-Key: i=tamird@kernel.org; a=openpgp; fpr=5A6714204D41EC844C50273C19D6FF6092365380 ringbuf_process_ring() checks the record bound only after advancing the consumer position and invoking the callback. A zero bound therefore consumes the first available record. Return before reading the ring positions when the bound is zero so ring_buffer__consume_n() and ring__consume_n() leave all records queued. Fixes: 4d22ea94ea33 ("libbpf: Add ring__consume_n / ring_buffer__consume_n") Reviewed-by: Emil Tsalapatis Assisted-by: Codex:gpt-5.5 Signed-off-by: Tamir Duberstein --- tools/lib/bpf/ringbuf.c | 3 +++ tools/testing/selftests/bpf/prog_tests/ringbuf.c | 13 +++++++++++++ 2 files changed, 16 insertions(+) diff --git a/tools/lib/bpf/ringbuf.c b/tools/lib/bpf/ringbuf.c index 00ec4837a06d..f2bb619d5a75 100644 --- a/tools/lib/bpf/ringbuf.c +++ b/tools/lib/bpf/ringbuf.c @@ -240,6 +240,9 @@ static int64_t ringbuf_process_ring(struct ring *r, size_t n) bool got_new_data; void *sample; + if (n == 0) + return 0; + cons_pos = smp_load_acquire(r->consumer_pos); do { got_new_data = false; diff --git a/tools/testing/selftests/bpf/prog_tests/ringbuf.c b/tools/testing/selftests/bpf/prog_tests/ringbuf.c index 64520684d2cb..4f0558f14847 100644 --- a/tools/testing/selftests/bpf/prog_tests/ringbuf.c +++ b/tools/testing/selftests/bpf/prog_tests/ringbuf.c @@ -404,6 +404,7 @@ static int process_n_sample(void *ctx, void *data, size_t len) static void ringbuf_n_subtest(void) { struct test_ringbuf_n_lskel *skel_n; + struct ring *ring; int err, i; skel_n = test_ringbuf_n_lskel__open(); @@ -431,6 +432,18 @@ static void ringbuf_n_subtest(void) for (i = 0; i < N_TOT_SAMPLES; i++) syscall(__NR_getpgid); + ring = ring_buffer__ring(ringbuf, 0); + if (!ASSERT_OK_PTR(ring, "ring_buffer__ring")) + goto cleanup_ringbuf; + + err = ring_buffer__consume_n(ringbuf, 0); + if (!ASSERT_EQ(err, 0, "ringbuf_consume_zero")) + goto cleanup_ringbuf; + + err = ring__consume_n(ring, 0); + if (!ASSERT_EQ(err, 0, "ring_consume_zero")) + goto cleanup_ringbuf; + /* Consume all samples from the ring buffer in batches of N_SAMPLES */ for (i = 0; i < N_TOT_SAMPLES; i += err) { err = ring_buffer__consume_n(ringbuf, N_SAMPLES); -- 2.55.0.rc0.159.gbe5d7338c2