From nobody Mon Apr 6 04:43:20 2026 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 A2002ECAAD3 for ; Sat, 10 Sep 2022 22:29:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229535AbiIJW3M (ORCPT ); Sat, 10 Sep 2022 18:29:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46058 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230037AbiIJW2S (ORCPT ); Sat, 10 Sep 2022 18:28:18 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 1317944562 for ; Sat, 10 Sep 2022 15:28:01 -0700 (PDT) Message-ID: <20220910222301.366236279@linutronix.de> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1662848878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=7h7DFq7DlMY8WzXRmdGz2plVQFhZnaozFR9FGyxDljo=; b=x/3ERXFx93KQf63lpOzkDVa73BmTwMDTxjJ6zoimc5QsGGE8W89awKZ6Qc0a/ubYEwpaBO IBoj40/rUogU28+Uhvy5ca40+ssoiBWqNyBgjRCxl4do/8nUOPE7aFJHNW9kCj8xRoJr++ GoocjZLn6Rb8vWZC2pRtWG/zKx2UqDXperdBQ/zOxvJbGySrWVZUVA4TtxH0uS1pVNBqb2 JXNvg60Mrnj0EBqC4eRxnulF9yHRR94vWr5wpbBAEATIXlb9hG3iyiuimOJQ0JxYXPZxEG KwCueJ33yS5MEZMM1BPZbqX952NfGjgQV2TV1McDELBWieUb19gmxZkxRU+U6g== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1662848878; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: references:references; bh=7h7DFq7DlMY8WzXRmdGz2plVQFhZnaozFR9FGyxDljo=; b=aY+++WRDc0UvwblV/17pD6tW6n1oN4ouvFQPQ3gKvM1VX7+Q6QLqQtl911Re1hGCgqBUlz 1MZV+l5Q5goUaUCQ== From: Thomas Gleixner To: LKML Cc: John Ogness , Petr Mladek , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Peter Zijlstra , "Paul E. McKenney" , Daniel Vetter , Greg Kroah-Hartman , Helge Deller , Jason Wessel , Daniel Thompson Subject: [patch RFC 17/29] printk: Use an output descriptor struct for emit References: <20220910221947.171557773@linutronix.de> MIME-Version: 1.0 Date: Sun, 11 Sep 2022 00:27:58 +0200 (CEST) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" To prepare for a new console infrastructure which is independent of the console BKL wrap the output mode into a descriptor struct so the new infrastrucure can share the emit code which dumps the ringbuffer record into the output text buffers. Signed-off-by: Thomas Gleixner --- include/linux/console.h | 15 +++++++ kernel/printk/printk.c | 94 ++++++++++++++++++++++++++++++++++---------= ----- 2 files changed, 82 insertions(+), 27 deletions(-) --- a/include/linux/console.h +++ b/include/linux/console.h @@ -187,6 +187,21 @@ struct cons_text_buf { }; =20 /** + * struct cons_outbuf_desc - console output buffer descriptor + * @txtbuf: Pointer to buffer for storing the text + * @outbuf: Pointer to the position in @buffer for + * writing it out to the device + * @len: Message length + * @extmsg: Select extended format printing + */ +struct cons_outbuf_desc { + struct cons_text_buf *txtbuf; + char *outbuf; + unsigned int len; + bool extmsg; +}; + +/** * struct console - The console descriptor structure * @name: The name of the console driver * @write: Write callback to output messages (Optional) --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -2684,40 +2684,39 @@ static void __console_unlock(void) up_console_sem(); } =20 -/* - * Print one record for the given console. The record printed is whatever - * record is the next available record for the given console. - * - * @text is a buffer of size CONSOLE_LOG_MAX. - * - * If extended messages should be printed, @ext_text is a buffer of size - * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL. - * - * If dropped messages should be printed, @dropped_text is a buffer of size - * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL. - * - * @handover will be set to true if a printk waiter has taken over the - * console_lock, in which case the caller is no longer holding the - * console_lock. Otherwise it is set to false. - * - * Returns false if the given console has no next record to print, otherwi= se - * true. + +/** + * cons_fill_outbuf - Fill the output buffer with the next record + * @con: The console to print on + * @desc: Pointer to the output descriptor + * + * The output descriptor contains all information which is necessary + * to print (buffer pointer, extended format selector...). + * + * Returns: False if there is no pending record in the ringbuffer + * True if there is a pending record in the ringbuffer. + * + * When the return value is true, then the caller has to check + * @desc->outbuf. If not NULL it points to the first character to write to + * the device and @desc->len contains the length of the message. * - * Requires the console_lock. + * If it is NULL then records have been dropped or skipped and con->seq + * has been forwarded so the caller can try to print the next record. */ -static bool console_emit_next_record(struct console *con, struct cons_text= _buf *txtbuf, - bool *handover, bool extmsg) +static bool cons_fill_outbuf(struct console *con, struct cons_outbuf_desc = *desc) { static int panic_console_dropped; + + struct cons_text_buf *txtbuf =3D desc->txtbuf; struct printk_info info; struct printk_record r; - unsigned long flags; char *write_text; size_t len; =20 - prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX); + desc->outbuf =3D NULL; + desc->len =3D 0; =20 - *handover =3D false; + prb_rec_init_rd(&r, &info, txtbuf->text, CONSOLE_LOG_MAX); =20 if (!prb_read_valid(prb, con->seq, &r)) return false; @@ -2734,10 +2733,10 @@ static bool console_emit_next_record(str /* Skip record that has level above the console loglevel. */ if (suppress_message_printing(r.info->level)) { con->seq++; - goto skip; + return true; } =20 - if (extmsg) { + if (desc->extmsg) { write_text =3D txtbuf->ext_text; len =3D info_print_ext_header(write_text, CONSOLE_EXT_LOG_MAX, r.info); len +=3D msg_print_ext_body(write_text + len, CONSOLE_EXT_LOG_MAX - len, @@ -2747,6 +2746,47 @@ static bool console_emit_next_record(str len =3D record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, pr= intk_time); } =20 + desc->len =3D len; + desc->outbuf =3D write_text; + return true; +} + +/** + * console_emit_next_record - Print one record for the given console + * @con: The console to print on + * @txtbuf: Pointer to the output buffer + * @handover: Pointer to Handover handshake storage + * @extmsg: Selects extended message format + * + * The record printed is whatever record is the next available record for + * the given console. + * + * @handover will be set to true if a printk waiter has taken over the + * console_lock, in which case the caller is no longer holding the + * console_lock. Otherwise it is set to false. + * + * Returns false if the given console has no next record to print, otherwi= se + * true. + * + * Requires the console_lock. + */ +static bool console_emit_next_record(struct console *con, struct cons_text= _buf *txtbuf, + bool *handover, bool extmsg) +{ + struct cons_outbuf_desc desc =3D { + .txtbuf =3D txtbuf, + .extmsg =3D extmsg, + }; + unsigned long flags; + + *handover =3D false; + + if (!cons_fill_outbuf(con, &desc)) + return false; + + if (!desc.outbuf) + goto skip; + /* * While actively printing out messages, if another printk() * were to occur on another CPU, it may wait for this one to @@ -2761,7 +2801,7 @@ static bool console_emit_next_record(str console_lock_spinning_enable(); =20 stop_critical_timings(); /* don't trace print latency */ - call_console_driver(con, write_text, len, extmsg ? NULL : txtbuf->dropped= _text); + call_console_driver(con, desc.outbuf, desc.len, extmsg ? NULL : txtbuf->d= ropped_text); start_critical_timings(); =20 con->seq++;