From nobody Thu Dec 18 07:53:31 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 48A58C7619A for ; Sat, 15 Apr 2023 10:01:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229890AbjDOKBW (ORCPT ); Sat, 15 Apr 2023 06:01:22 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55212 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229505AbjDOKBS (ORCPT ); Sat, 15 Apr 2023 06:01:18 -0400 Received: from mail-pf1-x42b.google.com (mail-pf1-x42b.google.com [IPv6:2607:f8b0:4864:20::42b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id CB9F53C1E for ; Sat, 15 Apr 2023 03:01:17 -0700 (PDT) Received: by mail-pf1-x42b.google.com with SMTP id d2e1a72fcca58-63b60366047so498313b3a.1 for ; Sat, 15 Apr 2023 03:01:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=chromium.org; s=google; t=1681552877; x=1684144877; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc:subject:date:message-id:reply-to; bh=xHqibnNY4gA+evDUThDgjACEqmKl0LOJc2RKlg79svA=; b=TGH9B4DUswCHmUGOcZZ+1lYnWG0x7dyyYJgZI+4xpwtGrfcjZCWcBnB/YyOBciGAUC Vo+Y0O+U3oueDwSAT1VvRQE8s15PKZaLMVaOdqhVXT8veO9CFDET0EDnJGf6FYDSRvQg /4wo8Wjohfpi9BswLyfCbwZ/UR0UKyX5mV5Ps= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681552877; x=1684144877; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=xHqibnNY4gA+evDUThDgjACEqmKl0LOJc2RKlg79svA=; b=OaRNIc/V8SOyhyuIfiW6dlRfhDcm6u8dUo84U0898FmnN7cJsXJB3qHLSqWiEVgewY bezdD3Kw+9SMlG9OgdSdPOfkomsUSIpSClqVxiMMso5FfDEcbTSdsVNgEmxYoAWCanIG lv3+UAc0iQ/unzezLEhHAnznmPXyrIlmI3EtrpElvsFkL+svDfg6Ue9y/qvp9LXQY+9q 5MyDAoVMAPJD9fnk3N1QZ+OtFnit2ksznr+uWsABeL0VV9fuMM0bfkfBIvOqav+Ay4wt GgFqTcq9Je8EoutmzZlG42yiu1xtKpCvEF3uvlk1QJqCWAaOYiDmtg9P/SscuCA24V0j R/ZQ== X-Gm-Message-State: AAQBX9d5fYpoTWqWLU4xGAD6UCq6Rd97nFPQt9yC9C4JlzRbNbh8i25j 8CVqa2WwwLZKFgx67dw8Y2BxJg== X-Google-Smtp-Source: AKy350YTzs0cX55VRFIMdPwWSA1UoMgHTy/om9EKcy+s3h6ZZ13HNLKax9hO0G1J1ALiI8ftnBXJrQ== X-Received: by 2002:a05:6a00:1402:b0:62d:e966:ffcb with SMTP id l2-20020a056a00140200b0062de966ffcbmr12826079pfu.0.1681552877311; Sat, 15 Apr 2023 03:01:17 -0700 (PDT) Received: from tigerii.tok.corp.google.com ([2401:fa00:8f:203:499e:18eb:4cc3:7e30]) by smtp.gmail.com with ESMTPSA id z9-20020aa791c9000000b0062e63cdfcb2sm4492112pfa.93.2023.04.15.03.01.15 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 15 Apr 2023 03:01:16 -0700 (PDT) From: Sergey Senozhatsky To: Steven Rostedt , Petr Mladek Cc: Andrew Morton , Yosry Ahmed , linux-kernel@vger.kernel.org, Sergey Senozhatsky Subject: [PATCHv3] seq_buf: add seq_buf_do_printk() helper Date: Sat, 15 Apr 2023 19:01:10 +0900 Message-ID: <20230415100110.1419872-1-senozhatsky@chromium.org> X-Mailer: git-send-email 2.40.0.634.g4ca3ef3211-goog 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" Sometimes we use seq_buf to format a string buffer, which we then pass to printk(). However, in certain situations the seq_buf string buffer can get too big, exceeding the PRINTKRB_RECORD_MAX bytes limit, and causing printk() to truncate the string. Add a new seq_buf helper. This helper prints the seq_buf string buffer line by line, using \n as a delimiter, rather than passing the whole string buffer to printk() at once. Signed-off-by: Sergey Senozhatsky Reviewed-by: Petr Mladek Tested-by: Yosry Ahmed --- include/linux/seq_buf.h | 2 ++ lib/seq_buf.c | 32 ++++++++++++++++++++++++++++++++ 2 files changed, 34 insertions(+) diff --git a/include/linux/seq_buf.h b/include/linux/seq_buf.h index 5b31c5147969..515d7fcb9634 100644 --- a/include/linux/seq_buf.h +++ b/include/linux/seq_buf.h @@ -159,4 +159,6 @@ extern int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary); #endif =20 +void seq_buf_do_printk(struct seq_buf *s, const char *lvl); + #endif /* _LINUX_SEQ_BUF_H */ diff --git a/lib/seq_buf.c b/lib/seq_buf.c index 0a68f7aa85d6..45c450f423fa 100644 --- a/lib/seq_buf.c +++ b/lib/seq_buf.c @@ -93,6 +93,38 @@ int seq_buf_printf(struct seq_buf *s, const char *fmt, .= ..) } EXPORT_SYMBOL_GPL(seq_buf_printf); =20 +/** + * seq_buf_do_printk - printk seq_buf line by line + * @s: seq_buf descriptor + * @lvl: printk level + * + * printk()-s a multi-line sequential buffer line by line. The function + * makes sure that the buffer in @s is nul terminated and safe to read + * as a string. + */ +void seq_buf_do_printk(struct seq_buf *s, const char *lvl) +{ + const char *start, *lf; + + if (s->size =3D=3D 0 || s->len =3D=3D 0) + return; + + seq_buf_terminate(s); + + start =3D s->buffer; + while ((lf =3D strchr(start, '\n'))) { + int len =3D lf - start + 1; + + printk("%s%.*s", lvl, len, start); + start =3D ++lf; + } + + /* No trailing LF */ + if (start < s->buffer + s->len) + printk("%s%s\n", lvl, start); +} +EXPORT_SYMBOL_GPL(seq_buf_do_printk); + #ifdef CONFIG_BINARY_PRINTF /** * seq_buf_bprintf - Write the printf string from binary arguments --=20 2.40.0.634.g4ca3ef3211-goog