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 33C35C433DB for ; Thu, 25 Feb 2021 20:26:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id EE03664F1B for ; Thu, 25 Feb 2021 20:26:49 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229769AbhBYU01 (ORCPT ); Thu, 25 Feb 2021 15:26:27 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:38246 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232473AbhBYUZ0 (ORCPT ); Thu, 25 Feb 2021 15:25:26 -0500 From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1614284682; 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=pZEnIipZrGhXuuERrPSOiy5gvUiRtoMxjnVriftYR3w=; b=08uCQNzX0p7/YeThPitCiF5DCpz3C/zRSxL8v4weXKIxTtiylLxAwBCBPgCGuuymwBzB46 r3PYSlLualKmcp+FeIOcJWXGc/DHrubKyifDWo6RBhuqU8QueFIV9lZzRNKsHdRP6uYYx9 9a9hQ7bRL7v4R8O/CgaAXPlcc1dKqCzxMjGm+ERCriFLwZ0Cr+7Bz7A+ybbI5SEBk4S6ah CL3/DKH5SKVAdgh/nmeXFYpSWEAU5D+ydT57YJP8nSzWjTjNR9+663v53gwwhPM/QhYt6J ermURd7G7xk+8h6blsdahO9fLianNlMsvLYDSrOg672zNF65jkRKSpqVruuVGQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1614284682; 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=pZEnIipZrGhXuuERrPSOiy5gvUiRtoMxjnVriftYR3w=; b=7c2ViMom4YwMaoEQphUxOCX1AjBXg3eCVtdW0zfFfcQZdzyk3AN5dgrJM2nLDP8p4CqGCM 0UlVrJSCSBFpJrCQ== To: Petr Mladek Cc: Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Thomas Gleixner , linux-kernel@vger.kernel.org, Pavel Tatashin , Kees Cook Subject: [PATCH next v3 05/15] printk: refactor kmsg_dump_get_buffer() Date: Thu, 25 Feb 2021 21:24:28 +0100 Message-Id: <20210225202438.28985-6-john.ogness@linutronix.de> In-Reply-To: <20210225202438.28985-1-john.ogness@linutronix.de> References: <20210225202438.28985-1-john.ogness@linutronix.de> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org kmsg_dump_get_buffer() requires nearly the same logic as syslog_print_all(), but uses different variable names and does not make use of the ringbuffer loop macros. Modify kmsg_dump_get_buffer() so that the implementation is as similar to syslog_print_all() as possible. A follow-up commit will move this common logic into a separate helper function. Signed-off-by: John Ogness Reviewed-by: Petr Mladek --- include/linux/kmsg_dump.h | 2 +- kernel/printk/printk.c | 62 +++++++++++++++++++++------------------ 2 files changed, 34 insertions(+), 30 deletions(-) diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h index ae38035f1dca..070c994ff19f 100644 --- a/include/linux/kmsg_dump.h +++ b/include/linux/kmsg_dump.h @@ -62,7 +62,7 @@ bool kmsg_dump_get_line(struct kmsg_dumper *dumper, bool syslog, char *line, size_t size, size_t *len); bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, - char *buf, size_t size, size_t *len); + char *buf, size_t size, size_t *len_out); void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper); diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 77ae2704e979..ed678d84dc51 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3410,7 +3410,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line); * @syslog: include the "<4>" prefixes * @buf: buffer to copy the line to * @size: maximum size of the buffer - * @len: length of line placed into buffer + * @len_out: length of line placed into buffer * * Start at the end of the kmsg buffer and fill the provided buffer * with as many of the *youngest* kmsg records that fit into it. @@ -3424,7 +3424,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line); * read. */ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, - char *buf, size_t size, size_t *len) + char *buf, size_t size, size_t *len_out) { struct printk_info info; unsigned int line_count; @@ -3432,12 +3432,10 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, unsigned long flags; u64 seq; u64 next_seq; - size_t l = 0; + size_t len = 0; bool ret = false; bool time = printk_time; - prb_rec_init_rd(&r, &info, buf, size); - if (!dumper->active || !buf || !size) goto out; @@ -3455,48 +3453,54 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, goto out; } - /* calculate length of entire buffer */ - seq = dumper->cur_seq; - while (prb_read_valid_info(prb, seq, &info, &line_count)) { - if (r.info->seq >= dumper->next_seq) + /* + * Find first record that fits, including all following records, + * into the user-provided buffer for this dump. + */ + + prb_for_each_info(dumper->cur_seq, prb, seq, &info, &line_count) { + if (info.seq >= dumper->next_seq) break; - l += get_record_print_text_size(&info, line_count, syslog, time); - seq = r.info->seq + 1; + len += get_record_print_text_size(&info, line_count, syslog, time); } - /* move first record forward until length fits into the buffer */ - seq = dumper->cur_seq; - while (l >= size && prb_read_valid_info(prb, seq, - &info, &line_count)) { - if (r.info->seq >= dumper->next_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 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; - l -= get_record_print_text_size(&info, line_count, syslog, time); - seq = r.info->seq + 1; + len -= get_record_print_text_size(&info, line_count, syslog, time); } - /* last message in next interation */ + /* + * Next kmsg_dump_get_buffer() invocation will dump block of + * older records stored right before this one. + */ next_seq = seq; - /* actually read text into the buffer now */ - l = 0; - while (prb_read_valid(prb, seq, &r)) { + prb_rec_init_rd(&r, &info, buf, size); + + len = 0; + prb_for_each_record(seq, prb, seq, &r) { if (r.info->seq >= dumper->next_seq) break; - l += record_print_text(&r, syslog, time); + len += record_print_text(&r, syslog, time); - /* adjust record to store to remaining buffer space */ - prb_rec_init_rd(&r, &info, buf + l, size - l); - - seq = r.info->seq + 1; + /* Adjust record to store to remaining buffer space. */ + prb_rec_init_rd(&r, &info, buf + len, size - len); } dumper->next_seq = next_seq; ret = true; logbuf_unlock_irqrestore(flags); out: - if (len) - *len = l; + if (len_out) + *len_out = len; return ret; } EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); -- 2.20.1