From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from xmbghk7.mail.qq.com (xmbghk7.mail.qq.com [43.163.128.54]) (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 9505A37B010; Sat, 15 Aug 2026 08:19:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=43.163.128.54 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786781977; cv=none; b=pzYOCSnmNqHrV07OQzoAiMzo/tUb5JuBwCcJe338i5MXcu+0Gtfnwb4XkmuyDqkVQM8lzN/9eQzPUymnleCwCNwXKgkyD7hmPUaTlAtk/huFY86VlikcISRL6i77xDSXhBWDZIH+QNmq3AFizjprD+S2SciBwfEyrwkZG8kys4c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786781977; c=relaxed/simple; bh=Vs5g3khHkihyDw3hVq3jxsqeUqUvikKNdyu2c3lVEf8=; h=Message-ID:From:To:Cc:Subject:Date:In-Reply-To:References: MIME-Version; b=o65VZ8t1A4KtIvTt7hWpR/F6jnItaFGwrIUm6EwExv2zN7f+ZXGQLGt+9bTlKKpkK21B1n/SPUyYXVa023D1Pe01IU2+7rvqAfzexAkqPY6Ggm1lJ7sJ2TByf0ENAeT8sPyLdVhSVAh/bcEtX1bsn+GhleoUvAyloMqMO7r4Ldo= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=foxmail.com; spf=pass smtp.mailfrom=foxmail.com; dkim=pass (1024-bit key) header.d=foxmail.com header.i=@foxmail.com header.b=uToQWy/E; arc=none smtp.client-ip=43.163.128.54 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=foxmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=foxmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=foxmail.com header.i=@foxmail.com header.b="uToQWy/E" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foxmail.com; s=s201512; t=1786781971; bh=PlTsX6f5WVGTG1fM/jy6eueWmXHqyeh0cZnGgAx93J8=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=uToQWy/Eg66hSn6Xm1GrJVPoHT5GTCKiZmGwKM1r5Gr9QcihGQPe5HTDS0oRgGEJR snhYyf8GVCJ5Hid8lw2TVowcprWNwddL1T9Sx7wsQ1v77TClzbF8piaJwnjcNXsa+V YFL5rvilZJOMVyjYyO3L1VaHPpeXuUL60dAWiLVA= Received: from localhost.localdomain ([180.153.160.8]) by newxmesmtplogicsvrsza63-0.qq.com (NewEsmtp) with SMTP id 4D51223E; Sat, 15 Aug 2026 16:19:21 +0800 X-QQ-mid: xmsmtpt1786781967tqvaa414q Message-ID: X-QQ-XMAILINFO: M+LbSN6IdDJLwMTXSHc1lUOejiM+Czskb7bwz1/zK9izEkY96RyjEFNHuQiI4m 9qRTH50Pmu4hHLpRgorb/65LaBIzp94kw8QQ7pwex2zB3Kq+vJA6YHZngLb2kFLT2+rkH0+9cCsC 7/wsnWLcIWQXDsmNTDCY7M2Up4cDDr2bo69LsipLFKhFRgbU0m+FwjtSrj2jIzBRO5dBAcn32T2j KklZbIi1WescC620YWNvEznSDr1uyPrznqoO6f7FCvbtvqRnyIv9O4sHmc5P4fmZW8OanwawPgjt We+13AS2Cst5E+I85eTxqiReQFsskK70DBN8FVSgU2evENFbJRdLRNupHh96B3buwxUael/3Yi97 ZPedRBHTTEpb4xWZWg8/Z1r3IZ1dr7nN0QQNDiR+u9COdeWS0sf/2wszCXBcJmEsXO/5r4WfSlGp yBe431ux4Vgm/AZSt//9OXe9GP0nVVhYyqLzRbRr7k573jM+9uzD+nCi7agyu8yXLX9B8RL0PCgN EA+/9vCjHDz43FMB6TJy4/vv5/ay7aK9Smuve8gYJJrrtetmLIwm+5uBydZEd5+yzpCY3MN73/Sv W4VNlMtLeJW8kwdoBBll01mE7sdANjDEPeXUhX+WapdaRWSW3x/hlIqZ+PgnfLJYWEBMOB892HUi ymU56mmAy0238wjkCWuUw35HQONlTBQxJtZKq2+vXGCwZvCKpYEqcnLXCftpSlNXauVqiMqcNC/M nFot91ZKiVE4EtcyR26cfKbi6CL0REwaOjVnSPrNgosw12pX58Tdi9xSLHsV7ghI+ESQJghnVWjF ww90Fcu+CAUWE5SSxJ2TmnAwJbUU5/seu+UcFAsB4w3JZlK2EdxwDy0IUHLYD0ylEwU3dPRYRoW7 Ry2Rd6S8GZk1TWfmzH21xs9pGfli2BsRCP8REvbkaMm2rsTlhslzBcoeLLGZbbNysvxRZiLpAQeB NuIVsIn9vOSpHTKRYPWz92xsSlJxcLBFKfL73ttzHk1i1NM9ayxEDZf7dPxDsyepeKKcSK9kceyl /djIlgSpIkRpElZq2Ku6dkI9Fk3gqkvBXE4pZxzXfzf2X4vOz4WORUXxI2PwBcsuTZoHlqoA== X-QQ-XMRINFO: NI4Ajvh11aEjEMj13RCX7UuhPEoou2bs1g== From: Jianlin Shi To: bpf@vger.kernel.org Cc: ast@kernel.org, daniel@iogearbox.net, andrii@kernel.org, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, yonghong.song@linux.dev, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, emil@etsalapatis.com, memxor@gmail.com, pulehui@huawei.com, shuah@kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH bpf-next v3 3/5] bpf: return partial progress from bpf_stream_read on fault Date: Sat, 15 Aug 2026 16:19:18 +0800 X-OQ-MSGID: <20260815081920.609936-4-shijianlin11@foxmail.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260815081920.609936-1-shijianlin11@foxmail.com> References: <20260815081920.609936-1-shijianlin11@foxmail.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit bpf_stream_read() pops and frees stream elements after a successful copy_to_user(). If a later copy_to_user() fails, it currently restores only the current element's consumed_len and returns -EFAULT, hiding bytes already delivered to userspace and making the consumed data unrecoverable on retry. On a short copy, keep the successfully copied prefix of the current element and return the number of bytes copied. Return -EFAULT only when no bytes were copied for the call. Fixes: 5ab154f1463a ("bpf: Introduce BPF standard streams") Signed-off-by: Jianlin Shi --- kernel/bpf/stream.c | 16 +++++++++------- 1 file changed, 9 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/stream.c b/kernel/bpf/stream.c index ef5a7b06ffcb..c1077160074c 100644 --- a/kernel/bpf/stream.c +++ b/kernel/bpf/stream.c @@ -167,6 +167,7 @@ static int bpf_stream_read(struct bpf_stream *stream, void __user *buf, int len) while (rem_len) { int pos = len - rem_len; + int chunk, n; bool cont; node = bpf_stream_backlog_peek(stream); @@ -180,13 +181,14 @@ static int bpf_stream_read(struct bpf_stream *stream, void __user *buf, int len) cons_len = elem->consumed_len; cont = bpf_stream_consume_elem(elem, &rem_len) == false; - - ret = copy_to_user(buf + pos, elem->str + cons_len, - elem->consumed_len - cons_len); - /* Restore in case of error. */ - if (ret) { - ret = -EFAULT; - elem->consumed_len = cons_len; + chunk = elem->consumed_len - cons_len; + + n = copy_to_user(buf + pos, elem->str + cons_len, chunk); + if (n) { + /* Keep any successfully copied bytes; -EFAULT only if none. */ + elem->consumed_len -= n; + rem_len += n; + ret = (len == rem_len) ? -EFAULT : 0; break; } -- 2.43.0