From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 74C73C433DB for ; Thu, 18 Feb 2021 09:40:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 32FE464D99 for ; Thu, 18 Feb 2021 09:40:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231846AbhBRJ3u (ORCPT ); Thu, 18 Feb 2021 04:29:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51524 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230469AbhBRITT (ORCPT ); Thu, 18 Feb 2021 03:19:19 -0500 Received: from galois.linutronix.de (Galois.linutronix.de [IPv6:2a0a:51c0:0:12e:550::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8CA93C06178B for ; Thu, 18 Feb 2021 00:18:22 -0800 (PST) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1613636299; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BzepJ7AJzP3TpbmyWwXwHCMWX+jwQ47rRBSE79MvDSk=; b=INikAX3EOfaEFmuaQfOf/yktpeimRZr2+2ZpRufjzYzfvhOIHa9OkIYuUvd5gXEvBsFKYH WFiW2obwewGmVjm0JxBIxSP4ESkhB5lMLzm7/VyoCDWqbe3QRODHze20Jv6OK2xQuQwfZq Pez470Sgzser4aopiIR7euddEbajNFsh3OV+qj+L0zGVhrH+iELdz+SvO1yLklRRHPX+PH KYDIz3ILZ/iRmns8UXdvo191HvFJP4b5dutTQJKU1O2XlRuATSTZGIHWScgePjfhaHybbj zm1ysQ4hjUOX/0zXad3/qKhKFWjGqnQ0iLTI/qI81Oe1FL8kn0jPZwZied2muA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1613636299; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=BzepJ7AJzP3TpbmyWwXwHCMWX+jwQ47rRBSE79MvDSk=; b=YtTthLsQtMt4gA9+N0UZlaswgGFkEUYJ//IP/mh8hlmoV3DrrsmM+BNEbB94AwF7exIX2k l01pDR5ABBtVWMCg== To: Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org Subject: [PATCH printk-rework 04/14] printk: consolidate kmsg_dump_get_buffer/syslog_print_all code Date: Thu, 18 Feb 2021 09:18:07 +0100 Message-Id: <20210218081817.28849-5-john.ogness@linutronix.de> In-Reply-To: <20210218081817.28849-1-john.ogness@linutronix.de> References: <20210218081817.28849-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org The logic for finding records to fit into a buffer is the same for kmsg_dump_get_buffer() and syslog_print_all(). Introduce a helper function find_first_fitting_seq() to handle this logic. Signed-off-by: John Ogness --- kernel/printk/printk.c | 87 ++++++++++++++++++++++++------------------ 1 file changed, 50 insertions(+), 37 deletions(-) diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index b4f72b5f70b9..d6f93ebd7bd0 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -1422,6 +1422,50 @@ static size_t get_record_print_text_size(struct printk_info *info, return ((prefix_len * line_count) + info->text_len + 1); } +/* + * Beginning with @start_seq, find the first record where it and all following + * records up to (but not including) @max_seq fit into @size. + * + * @max_seq is simply an upper bound and does not need to exist. If the caller + * does not require an upper bound, -1 can be used for @max_seq. + */ +static u64 find_first_fitting_seq(u64 start_seq, u64 max_seq, size_t size, + bool syslog, bool time) +{ + struct printk_info info; + unsigned int line_count; + size_t len = 0; + u64 seq; + + /* Determine the size of the records up to @max_seq. */ + prb_for_each_info(start_seq, prb, seq, &info, &line_count) { + if (info.seq >= max_seq) + break; + len += get_record_print_text_size(&info, line_count, syslog, time); + } + + /* + * Adjust the upper bound for the next loop to avoid subtracting + * lengths that were never added. + */ + if (seq < max_seq) + max_seq = seq; + + /* + * Move first record forward until length fits into the buffer. Ignore + * newest messages that were not counted in the above cycle. Messages + * might appear and get lost in the meantime. This is a best effort + * that prevents an infinite loop that could occur with a retry. + */ + prb_for_each_info(start_seq, prb, seq, &info, &line_count) { + if (len <= size || info.seq >= max_seq) + break; + len -= get_record_print_text_size(&info, line_count, syslog, time); + } + + return seq; +} + static int syslog_print(char __user *buf, int size) { struct printk_info info; @@ -1493,9 +1537,7 @@ static int syslog_print(char __user *buf, int size) static int syslog_print_all(char __user *buf, int size, bool clear) { struct printk_info info; - unsigned int line_count; struct printk_record r; - u64 max_seq; char *text; int len = 0; u64 seq; @@ -1511,21 +1553,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear) * Find first record that fits, including all following records, * into the user-provided buffer for this dump. */ - prb_for_each_info(clear_seq, prb, seq, &info, &line_count) - len += get_record_print_text_size(&info, line_count, true, time); - - /* - * Set an upper bound for the next loop to avoid subtracting lengths - * that were never added. - */ - max_seq = seq; - - /* move first record forward until length fits into the buffer */ - prb_for_each_info(clear_seq, prb, seq, &info, &line_count) { - if (len <= size || info.seq >= max_seq) - break; - len -= get_record_print_text_size(&info, line_count, true, time); - } + seq = find_first_fitting_seq(clear_seq, -1, size, true, time); prb_rec_init_rd(&r, &info, text, LOG_LINE_MAX + PREFIX_MAX); @@ -3423,7 +3451,6 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, char *buf, size_t size, size_t *len_out) { struct printk_info info; - unsigned int line_count; struct printk_record r; unsigned long flags; u64 seq; @@ -3451,26 +3478,12 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, /* * Find first record that fits, including all following records, - * into the user-provided buffer for this dump. + * into the user-provided buffer for this dump. Pass in size-1 + * because this function (by way of record_print_text()) will + * not write more than size-1 bytes of text into @buf. */ - - prb_for_each_info(dumper->cur_seq, prb, seq, &info, &line_count) { - if (info.seq >= dumper->next_seq) - break; - len += get_record_print_text_size(&info, line_count, syslog, time); - } - - /* - * Move first record forward until length fits into the buffer. Ignore - * newest messages that were not counted in the above cycle. Messages - * might appear and get lost in the meantime. This is the best effort - * that prevents an infinite loop. - */ - prb_for_each_info(dumper->cur_seq, prb, seq, &info, &line_count) { - if (len < size || info.seq >= dumper->next_seq) - break; - len -= get_record_print_text_size(&info, line_count, syslog, time); - } + seq = find_first_fitting_seq(dumper->cur_seq, dumper->next_seq, + size - 1, syslog, time); /* * Next kmsg_dump_get_buffer() invocation will dump block of -- 2.20.1