Received: by 2002:a25:1506:0:0:0:0:0 with SMTP id 6csp1754988ybv; Fri, 14 Feb 2020 05:30:11 -0800 (PST) X-Google-Smtp-Source: APXvYqzq9sgJ5IFFw0sQKHxgItCQEpoY9Lf6Zss4JjWeVLNIXg4wAejZa9cFCZ5ZTxeC6EChn8LE X-Received: by 2002:aca:2407:: with SMTP id n7mr1908662oic.14.1581687011529; Fri, 14 Feb 2020 05:30:11 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1581687011; cv=none; d=google.com; s=arc-20160816; b=tg9iMsVeQcJNusdHpOTJWk/kB/rsMkKulCkkEQHtKje9csLtHc41Kl07ozqJH4Ie4W sf67qIyPAlXj1lhgIyweJ5XS3lQLBeXWLXhdRFSIj1QvfEsPw/e4OY6Ni8mikIYF5WQn AUT2PKnfAOPs+As1MqC34WJ/xIeTf32j1vg05HtvoTaTEdZm+ggHBLrNcfGRime6T2yI 86DWBKblK1qN1c/HIWGGvDPd2/Ac5uHYmh2aasjv8nIZpMEoQS0xAJ4xRGssxNf9EfTg eRRGE9FVEkfPCZNQe6O2PZQRfzL7iTjJgnq99ABbLI70y6j+muSI2dxbPlKdKFjxx10H QRxg== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:from:references:cc:to:subject:dkim-signature; bh=W/8ILaB0zsU/H7AUCCYBmUtn1Jd/MLd/GbjKL0Xgu7M=; b=pBaPnJFRn0DCbswZNM4MpBL9RVEBVPWYk9o4NUvJVfs6KJQ3yVzAAAMcIWoj97vIPY jw5jqv9CJgGcQuLwdGdWb9WmvVtW3Of+vyhZ364Ncs0J/ke2HY74xVkadq8ZUObZxSdB 2003cHKsByQqJiDW18xIr375eguPh3BcloCMXbaj2C8QN/OH4PmknNkK5Vj3nkCdXHSz nXJK2SxpLBFSr1Us3PweJ4RjNSKhm08g6U5PXgne2eJmp15JxCX7fJRITsRzZSAbbe8F Jbr+7malDNr+0vMGA8aR6y6L6TIw2pYfi3jhfv6DY6sOUQ6BfzVPnfbqZ9WTiRzZXrGW 19mQ== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=PRSQ7z7a; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Return-Path: Received: from vger.kernel.org (vger.kernel.org. [209.132.180.67]) by mx.google.com with ESMTP id n20si2574003oig.53.2020.02.14.05.29.59; Fri, 14 Feb 2020 05:30:11 -0800 (PST) Received-SPF: pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=PRSQ7z7a; spf=pass (google.com: best guess record for domain of linux-kernel-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729259AbgBNN3n (ORCPT + 99 others); Fri, 14 Feb 2020 08:29:43 -0500 Received: from us-smtp-delivery-1.mimecast.com ([207.211.31.120]:23506 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727822AbgBNN3n (ORCPT ); Fri, 14 Feb 2020 08:29:43 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1581686982; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=W/8ILaB0zsU/H7AUCCYBmUtn1Jd/MLd/GbjKL0Xgu7M=; b=PRSQ7z7atW/XyQ4ORGEf4AdY49PrBWoSk3QEsCxXcrUBSDSU2SiLaBzWuky8aa17r0Yvvw p50VBCLUPX+stOX79Vhjd57/MCYVktC8FqiLlLwC+rmOU6PyYFb2HeHi7ChKDgpTNk+08a Z9S+4oRIosry0C6kn4JCdzJeuMPpcfw= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-25-26jyM-XoMPqS42sPtK5DNg-1; Fri, 14 Feb 2020 08:29:36 -0500 X-MC-Unique: 26jyM-XoMPqS42sPtK5DNg-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 88BBF800D4E; Fri, 14 Feb 2020 13:29:34 +0000 (UTC) Received: from localhost.localdomain (ovpn-12-202.pek2.redhat.com [10.72.12.202]) by smtp.corp.redhat.com (Postfix) with ESMTPS id BA39D8642B; Fri, 14 Feb 2020 13:29:27 +0000 (UTC) Subject: Re: [PATCH 2/2] printk: use the lockless ringbuffer To: John Ogness Cc: Petr Mladek , Peter Zijlstra , Sergey Senozhatsky , Sergey Senozhatsky , Steven Rostedt , Linus Torvalds , Greg Kroah-Hartman , Andrea Parri , Thomas Gleixner , kexec@lists.infradead.org, linux-kernel@vger.kernel.org References: <20200128161948.8524-1-john.ogness@linutronix.de> <20200128161948.8524-3-john.ogness@linutronix.de> From: lijiang Message-ID: Date: Fri, 14 Feb 2020 21:29:23 +0800 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <20200128161948.8524-3-john.ogness@linutronix.de> Content-Type: text/plain; charset=UTF-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org =E5=9C=A8 2020=E5=B9=B401=E6=9C=8829=E6=97=A5 00:19, John Ogness =E5=86=99= =E9=81=93: > Replace the existing ringbuffer usage and implementation with > lockless ringbuffer usage. Even though the new ringbuffer does not > require locking, all existing locking is left in place. Therefore, > this change is purely replacing the underlining ringbuffer. >=20 > Changes that exist due to the ringbuffer replacement: >=20 > - The VMCOREINFO has been updated for the new structures. >=20 > - Dictionary data is now stored in a separate data buffer from the > human-readable messages. The dictionary data buffer is set to the > same size as the message buffer. Therefore, the total reserved > memory for messages is 2 * (2 ^ CONFIG_LOG_BUF_SHIFT) for the > initial static buffer and 2x the specified size in the log_buf_len > kernel parameter. >=20 > - Record meta-data is now stored in a separate array of descriptors. > This is an additional 72 * (2 ^ ((CONFIG_LOG_BUF_SHIFT - 6))) bytes > for the static array and 72 * (2 ^ ((log_buf_len - 6))) bytes for > the dynamic array. >=20 > Signed-off-by: John Ogness > --- > include/linux/kmsg_dump.h | 2 - > kernel/printk/Makefile | 1 + > kernel/printk/printk.c | 836 +++++++++++++++++++------------------- > 3 files changed, 416 insertions(+), 423 deletions(-) >=20 > diff --git a/include/linux/kmsg_dump.h b/include/linux/kmsg_dump.h > index 2e7a1e032c71..ae6265033e31 100644 > --- a/include/linux/kmsg_dump.h > +++ b/include/linux/kmsg_dump.h > @@ -46,8 +46,6 @@ struct kmsg_dumper { > bool registered; > =20 > /* private state of the kmsg iterator */ > - u32 cur_idx; > - u32 next_idx; > u64 cur_seq; > u64 next_seq; > }; > diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile > index 4d052fc6bcde..eee3dc9b60a9 100644 > --- a/kernel/printk/Makefile > +++ b/kernel/printk/Makefile > @@ -2,3 +2,4 @@ > obj-y =3D printk.o > obj-$(CONFIG_PRINTK) +=3D printk_safe.o > obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) +=3D braille.o > +obj-$(CONFIG_PRINTK) +=3D printk_ringbuffer.o > diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c > index 1ef6f75d92f1..d0d24ee1d1f4 100644 > --- a/kernel/printk/printk.c > +++ b/kernel/printk/printk.c > @@ -56,6 +56,7 @@ > #define CREATE_TRACE_POINTS > #include > =20 > +#include "printk_ringbuffer.h" > #include "console_cmdline.h" > #include "braille.h" > #include "internal.h" > @@ -294,30 +295,22 @@ enum con_msg_format_flags { > static int console_msg_format =3D MSG_FORMAT_DEFAULT; > =20 > /* > - * The printk log buffer consists of a chain of concatenated variable > - * length records. Every record starts with a record header, containin= g > - * the overall length of the record. > + * The printk log buffer consists of a sequenced collection of records= , each > + * containing variable length message and dictionary text. Every recor= d > + * also contains its own meta-data (@info). > * > - * The heads to the first and last entry in the buffer, as well as the > - * sequence numbers of these entries are maintained when messages are > - * stored. > - * > - * If the heads indicate available messages, the length in the header > - * tells the start next message. A length =3D=3D 0 for the next messag= e > - * indicates a wrap-around to the beginning of the buffer. > - * > - * Every record carries the monotonic timestamp in microseconds, as we= ll as > - * the standard userspace syslog level and syslog facility. The usual > + * Every record meta-data carries the monotonic timestamp in microseco= nds, as > + * well as the standard userspace syslog level and syslog facility. Th= e usual > * kernel messages use LOG_KERN; userspace-injected messages always ca= rry > * a matching syslog facility, by default LOG_USER. The origin of ever= y > * message can be reliably determined that way. > * > - * The human readable log message directly follows the message header.= The > - * length of the message text is stored in the header, the stored mess= age > - * is not terminated. > + * The human readable log message of a record is available in @text, t= he length > + * of the message text in @text_len. The stored message is not termina= ted. > * > - * Optionally, a message can carry a dictionary of properties (key/val= ue pairs), > - * to provide userspace with a machine-readable message context. > + * Optionally, a record can carry a dictionary of properties (key/valu= e pairs), > + * to provide userspace with a machine-readable message context. The l= ength of > + * the dictionary is available in @dict_len. The dictionary is not ter= minated. > * > * Examples for well-defined, commonly used property names are: > * DEVICE=3Db12:8 device identifier > @@ -331,21 +324,19 @@ static int console_msg_format =3D MSG_FORMAT_DEFA= ULT; > * follows directly after a '=3D' character. Every property is termina= ted by > * a '\0' character. The last property is not terminated. > * > - * Example of a message structure: > - * 0000 ff 8f 00 00 00 00 00 00 monotonic time in nsec > - * 0008 34 00 record is 52 bytes long > - * 000a 0b 00 text is 11 bytes long > - * 000c 1f 00 dictionary is 23 bytes long > - * 000e 03 00 LOG_KERN (facility) LOG_ERR (l= evel) > - * 0010 69 74 27 73 20 61 20 6c "it's a l" > - * 69 6e 65 "ine" > - * 001b 44 45 56 49 43 "DEVIC" > - * 45 3d 62 38 3a 32 00 44 "E=3Db8:2\0D" > - * 52 49 56 45 52 3d 62 75 "RIVER=3Dbu" > - * 67 "g" > - * 0032 00 00 00 padding to next message header > - * > - * The 'struct printk_log' buffer header must never be directly export= ed to > + * Example of record values: > + * record.text_buf =3D "it's a line" (unterminated) > + * record.dict_buf =3D "DEVICE=3Db8:2\0DRIVER=3Dbug" (untermin= ated) > + * record.info.seq =3D 56 > + * record.info.ts_sec =3D 36863 > + * record.info.text_len =3D 11 > + * record.info.dict_len =3D 22 > + * record.info.facility =3D 0 (LOG_KERN) > + * record.info.flags =3D 0 > + * record.info.level =3D 3 (LOG_ERR) > + * record.info.caller_id =3D 299 (task 299) > + * > + * The 'struct printk_info' buffer must never be directly exported to > * userspace, it is a kernel-private implementation detail that might > * need to be changed in the future, when the requirements change. > * > @@ -365,23 +356,6 @@ enum log_flags { > LOG_CONT =3D 8, /* text is a fragment of a continuation line */ > }; > =20 > -struct printk_log { > - u64 ts_nsec; /* timestamp in nanoseconds */ > - u16 len; /* length of entire record */ > - u16 text_len; /* length of text buffer */ > - u16 dict_len; /* length of dictionary buffer */ > - u8 facility; /* syslog facility */ > - u8 flags:5; /* internal record flags */ > - u8 level:3; /* syslog level */ > -#ifdef CONFIG_PRINTK_CALLER > - u32 caller_id; /* thread id or processor id */ > -#endif > -} > -#ifdef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS > -__packed __aligned(4) > -#endif > -; > - > /* > * The logbuf_lock protects kmsg buffer, indices, counters. This can = be taken > * within the scheduler's rq lock. It must be released before calling > @@ -421,26 +395,17 @@ DEFINE_RAW_SPINLOCK(logbuf_lock); > DECLARE_WAIT_QUEUE_HEAD(log_wait); > /* the next printk record to read by syslog(READ) or /proc/kmsg */ > static u64 syslog_seq; > -static u32 syslog_idx; > static size_t syslog_partial; > static bool syslog_time; > - > -/* index and sequence number of the first record stored in the buffer = */ > -static u64 log_first_seq; > -static u32 log_first_idx; > - > -/* index and sequence number of the next record to store in the buffer= */ > -static u64 log_next_seq; > -static u32 log_next_idx; > +DECLARE_PRINTKRB_RECORD(syslog_record, CONSOLE_EXT_LOG_MAX); > =20 > /* the next printk record to write to the console */ > static u64 console_seq; > -static u32 console_idx; > static u64 exclusive_console_stop_seq; > +DECLARE_PRINTKRB_RECORD(console_record, CONSOLE_EXT_LOG_MAX); > =20 > /* the next printk record to read after the last 'clear' command */ > static u64 clear_seq; > -static u32 clear_idx; > =20 > #ifdef CONFIG_PRINTK_CALLER > #define PREFIX_MAX 48 > @@ -453,13 +418,28 @@ static u32 clear_idx; > #define LOG_FACILITY(v) ((v) >> 3 & 0xff) > =20 > /* record buffer */ > -#define LOG_ALIGN __alignof__(struct printk_log) > +#define LOG_ALIGN __alignof__(unsigned long) > #define __LOG_BUF_LEN (1 << CONFIG_LOG_BUF_SHIFT) > #define LOG_BUF_LEN_MAX (u32)(1 << 31) > static char __log_buf[__LOG_BUF_LEN] __aligned(LOG_ALIGN); > static char *log_buf =3D __log_buf; > static u32 log_buf_len =3D __LOG_BUF_LEN; > =20 > +/* > + * Define the average message size. This only affects the number of > + * descriptors that will be available. Underestimating is better than > + * overestimating (too many available descriptors is better than not e= nough). > + * The dictionary buffer will be the same size as the text buffer. > + */ > +#define PRB_AVGBITS 6 > + > +_DECLARE_PRINTKRB(printk_rb_static, CONFIG_LOG_BUF_SHIFT - PRB_AVGBITS= , > + PRB_AVGBITS, PRB_AVGBITS, &__log_buf[0]); > + > +static struct printk_ringbuffer printk_rb_dynamic; > + > +static struct printk_ringbuffer *prb =3D &printk_rb_static; > + > /* Return log buffer address */ > char *log_buf_addr_get(void) > { > @@ -472,108 +452,6 @@ u32 log_buf_len_get(void) > return log_buf_len; > } > =20 > -/* human readable text of the record */ > -static char *log_text(const struct printk_log *msg) > -{ > - return (char *)msg + sizeof(struct printk_log); > -} > - > -/* optional key/value pair dictionary attached to the record */ > -static char *log_dict(const struct printk_log *msg) > -{ > - return (char *)msg + sizeof(struct printk_log) + msg->text_len; > -} > - > -/* get record by index; idx must point to valid msg */ > -static struct printk_log *log_from_idx(u32 idx) > -{ > - struct printk_log *msg =3D (struct printk_log *)(log_buf + idx); > - > - /* > - * A length =3D=3D 0 record is the end of buffer marker. Wrap around = and > - * read the message at the start of the buffer. > - */ > - if (!msg->len) > - return (struct printk_log *)log_buf; > - return msg; > -} > - > -/* get next record; idx must point to valid msg */ > -static u32 log_next(u32 idx) > -{ > - struct printk_log *msg =3D (struct printk_log *)(log_buf + idx); > - > - /* length =3D=3D 0 indicates the end of the buffer; wrap */ > - /* > - * A length =3D=3D 0 record is the end of buffer marker. Wrap around = and > - * read the message at the start of the buffer as *this* one, and > - * return the one after that. > - */ > - if (!msg->len) { > - msg =3D (struct printk_log *)log_buf; > - return msg->len; > - } > - return idx + msg->len; > -} > - > -/* > - * Check whether there is enough free space for the given message. > - * > - * The same values of first_idx and next_idx mean that the buffer > - * is either empty or full. > - * > - * If the buffer is empty, we must respect the position of the indexes= . > - * They cannot be reset to the beginning of the buffer. > - */ > -static int logbuf_has_space(u32 msg_size, bool empty) > -{ > - u32 free; > - > - if (log_next_idx > log_first_idx || empty) > - free =3D max(log_buf_len - log_next_idx, log_first_idx); > - else > - free =3D log_first_idx - log_next_idx; > - > - /* > - * We need space also for an empty header that signalizes wrapping > - * of the buffer. > - */ > - return free >=3D msg_size + sizeof(struct printk_log); > -} > - > -static int log_make_free_space(u32 msg_size) > -{ > - while (log_first_seq < log_next_seq && > - !logbuf_has_space(msg_size, false)) { > - /* drop old messages until we have enough contiguous space */ > - log_first_idx =3D log_next(log_first_idx); > - log_first_seq++; > - } > - > - if (clear_seq < log_first_seq) { > - clear_seq =3D log_first_seq; > - clear_idx =3D log_first_idx; > - } > - > - /* sequence numbers are equal, so the log buffer is empty */ > - if (logbuf_has_space(msg_size, log_first_seq =3D=3D log_next_seq)) > - return 0; > - > - return -ENOMEM; > -} > - > -/* compute the message size including the padding bytes */ > -static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len) > -{ > - u32 size; > - > - size =3D sizeof(struct printk_log) + text_len + dict_len; > - *pad_len =3D (-size) & (LOG_ALIGN - 1); > - size +=3D *pad_len; > - > - return size; > -} > - > /* > * Define how much of the log buffer we could take at maximum. The val= ue > * must be greater than two. Note that only half of the buffer is avai= lable > @@ -582,22 +460,26 @@ static u32 msg_used_size(u16 text_len, u16 dict_l= en, u32 *pad_len) > #define MAX_LOG_TAKE_PART 4 > static const char trunc_msg[] =3D ""; > =20 > -static u32 truncate_msg(u16 *text_len, u16 *trunc_msg_len, > - u16 *dict_len, u32 *pad_len) > +static void truncate_msg(u16 *text_len, u16 *trunc_msg_len, u16 *dict_= len) > { > /* > * The message should not take the whole buffer. Otherwise, it might > * get removed too soon. > */ > u32 max_text_len =3D log_buf_len / MAX_LOG_TAKE_PART; > + > if (*text_len > max_text_len) > *text_len =3D max_text_len; > - /* enable the warning message */ > + > + /* enable the warning message (if there is room) */ > *trunc_msg_len =3D strlen(trunc_msg); > + if (*text_len >=3D *trunc_msg_len) > + *text_len -=3D *trunc_msg_len; > + else > + *trunc_msg_len =3D 0; > + > /* disable the "dict" completely */ > *dict_len =3D 0; > - /* compute the size again, count also the warning message */ > - return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len); > } > =20 > /* insert record into the buffer, discard old ones, update heads */ > @@ -606,60 +488,42 @@ static int log_store(u32 caller_id, int facility,= int level, > const char *dict, u16 dict_len, > const char *text, u16 text_len) > { > - struct printk_log *msg; > - u32 size, pad_len; > + struct prb_reserved_entry e; > + struct printk_record r; > u16 trunc_msg_len =3D 0; > =20 > - /* number of '\0' padding bytes to next message */ > - size =3D msg_used_size(text_len, dict_len, &pad_len); > + r.text_buf_size =3D text_len; > + r.dict_buf_size =3D dict_len; > =20 > - if (log_make_free_space(size)) { > + if (!prb_reserve(&e, prb, &r)) { > /* truncate the message if it is too long for empty buffer */ > - size =3D truncate_msg(&text_len, &trunc_msg_len, > - &dict_len, &pad_len); > + truncate_msg(&text_len, &trunc_msg_len, &dict_len); > + r.text_buf_size =3D text_len + trunc_msg_len; > + r.dict_buf_size =3D dict_len; > /* survive when the log buffer is too small for trunc_msg */ > - if (log_make_free_space(size)) > + if (!prb_reserve(&e, prb, &r)) > return 0; > } > =20 > - if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) { > - /* > - * This message + an additional empty header does not fit > - * at the end of the buffer. Add an empty header with len =3D=3D 0 > - * to signify a wrap around. > - */ > - memset(log_buf + log_next_idx, 0, sizeof(struct printk_log)); > - log_next_idx =3D 0; > - } > - > /* fill message */ > - msg =3D (struct printk_log *)(log_buf + log_next_idx); > - memcpy(log_text(msg), text, text_len); > - msg->text_len =3D text_len; > - if (trunc_msg_len) { > - memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len); > - msg->text_len +=3D trunc_msg_len; > - } > - memcpy(log_dict(msg), dict, dict_len); > - msg->dict_len =3D dict_len; > - msg->facility =3D facility; > - msg->level =3D level & 7; > - msg->flags =3D flags & 0x1f; > + memcpy(&r.text_buf[0], text, text_len); > + if (trunc_msg_len) > + memcpy(&r.text_buf[text_len], trunc_msg, trunc_msg_len); > + if (r.dict_buf) > + memcpy(&r.dict_buf[0], dict, dict_len); > + r.info->facility =3D facility; > + r.info->level =3D level & 7; > + r.info->flags =3D flags & 0x1f; > if (ts_nsec > 0) > - msg->ts_nsec =3D ts_nsec; > + r.info->ts_nsec =3D ts_nsec; > else > - msg->ts_nsec =3D local_clock(); > -#ifdef CONFIG_PRINTK_CALLER > - msg->caller_id =3D caller_id; > -#endif > - memset(log_dict(msg) + dict_len, 0, pad_len); > - msg->len =3D size; > + r.info->ts_nsec =3D local_clock(); > + r.info->caller_id =3D caller_id; > =20 > /* insert message */ > - log_next_idx +=3D msg->len; > - log_next_seq++; > + prb_commit(&e); > =20 > - return msg->text_len; > + return text_len; > } > =20 > int dmesg_restrict =3D IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT); > @@ -711,13 +575,13 @@ static void append_char(char **pp, char *e, char = c) > *(*pp)++ =3D c; > } > =20 > -static ssize_t msg_print_ext_header(char *buf, size_t size, > - struct printk_log *msg, u64 seq) > +static ssize_t info_print_ext_header(char *buf, size_t size, > + struct printk_info *info) > { > - u64 ts_usec =3D msg->ts_nsec; > + u64 ts_usec =3D info->ts_nsec; > char caller[20]; > #ifdef CONFIG_PRINTK_CALLER > - u32 id =3D msg->caller_id; > + u32 id =3D info->caller_id; > =20 > snprintf(caller, sizeof(caller), ",caller=3D%c%u", > id & 0x80000000 ? 'C' : 'T', id & ~0x80000000); > @@ -728,8 +592,8 @@ static ssize_t msg_print_ext_header(char *buf, size= _t size, > do_div(ts_usec, 1000); > =20 > return scnprintf(buf, size, "%u,%llu,%llu,%c%s;", > - (msg->facility << 3) | msg->level, seq, ts_usec, > - msg->flags & LOG_CONT ? 'c' : '-', caller); > + (info->facility << 3) | info->level, info->seq, > + ts_usec, info->flags & LOG_CONT ? 'c' : '-', caller); > } > =20 > static ssize_t msg_print_ext_body(char *buf, size_t size, > @@ -783,10 +647,14 @@ static ssize_t msg_print_ext_body(char *buf, size= _t size, > /* /dev/kmsg - userspace message inject/listen interface */ > struct devkmsg_user { > u64 seq; > - u32 idx; > struct ratelimit_state rs; > struct mutex lock; > char buf[CONSOLE_EXT_LOG_MAX]; > + > + struct printk_info info; > + char text_buf[CONSOLE_EXT_LOG_MAX]; > + char dict_buf[CONSOLE_EXT_LOG_MAX]; > + struct printk_record record; > }; > =20 > static __printf(3, 4) __cold > @@ -869,7 +737,7 @@ static ssize_t devkmsg_read(struct file *file, char= __user *buf, > size_t count, loff_t *ppos) > { > struct devkmsg_user *user =3D file->private_data; > - struct printk_log *msg; > + struct printk_record *r =3D &user->record; > size_t len; > ssize_t ret; > =20 > @@ -881,7 +749,7 @@ static ssize_t devkmsg_read(struct file *file, char= __user *buf, > return ret; > =20 > logbuf_lock_irq(); > - while (user->seq =3D=3D log_next_seq) { > + if (!prb_read_valid(prb, user->seq, r)) { > if (file->f_flags & O_NONBLOCK) { > ret =3D -EAGAIN; > logbuf_unlock_irq(); > @@ -890,30 +758,26 @@ static ssize_t devkmsg_read(struct file *file, ch= ar __user *buf, > =20 > logbuf_unlock_irq(); > ret =3D wait_event_interruptible(log_wait, > - user->seq !=3D log_next_seq); > + prb_read_valid(prb, user->seq, r)); > if (ret) > goto out; > logbuf_lock_irq(); > } > =20 > - if (user->seq < log_first_seq) { > - /* our last seen message is gone, return error and reset */ > - user->idx =3D log_first_idx; > - user->seq =3D log_first_seq; > + if (user->seq < r->info->seq) { > + /* the expected message is gone, return error and reset */ > + user->seq =3D r->info->seq; > ret =3D -EPIPE; > logbuf_unlock_irq(); > goto out; > } > =20 > - msg =3D log_from_idx(user->idx); > - len =3D msg_print_ext_header(user->buf, sizeof(user->buf), > - msg, user->seq); > + len =3D info_print_ext_header(user->buf, sizeof(user->buf), r->info); > len +=3D msg_print_ext_body(user->buf + len, sizeof(user->buf) - len, > - log_dict(msg), msg->dict_len, > - log_text(msg), msg->text_len); > + &r->dict_buf[0], r->info->dict_len, > + &r->text_buf[0], r->info->text_len); > =20 > - user->idx =3D log_next(user->idx); > - user->seq++; > + user->seq =3D r->info->seq + 1; > logbuf_unlock_irq(); > =20 > if (len > count) { > @@ -945,8 +809,7 @@ static loff_t devkmsg_llseek(struct file *file, lof= f_t offset, int whence) > switch (whence) { > case SEEK_SET: > /* the first record */ > - user->idx =3D log_first_idx; > - user->seq =3D log_first_seq; > + user->seq =3D prb_first_seq(prb); > break; > case SEEK_DATA: > /* > @@ -954,13 +817,11 @@ static loff_t devkmsg_llseek(struct file *file, l= off_t offset, int whence) > * like issued by 'dmesg -c'. Reading /dev/kmsg itself > * changes no global state, and does not clear anything. > */ > - user->idx =3D clear_idx; > user->seq =3D clear_seq; > break; > case SEEK_END: > /* after the last record */ > - user->idx =3D log_next_idx; > - user->seq =3D log_next_seq; > + user->seq =3D prb_next_seq(prb); > break; > default: > ret =3D -EINVAL; > @@ -980,9 +841,9 @@ static __poll_t devkmsg_poll(struct file *file, pol= l_table *wait) > poll_wait(file, &log_wait, wait); > =20 > logbuf_lock_irq(); > - if (user->seq < log_next_seq) { > + if (prb_read_valid(prb, user->seq, NULL)) { > /* return error when data has vanished underneath us */ > - if (user->seq < log_first_seq) > + if (user->seq < prb_first_seq(prb)) > ret =3D EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI; > else > ret =3D EPOLLIN|EPOLLRDNORM; > @@ -1017,9 +878,14 @@ static int devkmsg_open(struct inode *inode, stru= ct file *file) > =20 > mutex_init(&user->lock); > =20 > + user->record.info =3D &user->info; > + user->record.text_buf =3D &user->text_buf[0]; > + user->record.text_buf_size =3D sizeof(user->text_buf); > + user->record.dict_buf =3D &user->dict_buf[0]; > + user->record.dict_buf_size =3D sizeof(user->dict_buf); > + > logbuf_lock_irq(); > - user->idx =3D log_first_idx; > - user->seq =3D log_first_seq; > + user->seq =3D prb_first_seq(prb); > logbuf_unlock_irq(); > =20 > file->private_data =3D user; > @@ -1062,21 +928,16 @@ void log_buf_vmcoreinfo_setup(void) > { > VMCOREINFO_SYMBOL(log_buf); > VMCOREINFO_SYMBOL(log_buf_len); Hi, John Ogness I notice that the "prb"(printk tb static) symbol is not exported into vmc= oreinfo as follows: + VMCOREINFO_SYMBOL(prb); Should the "prb"(printk tb static) symbol be exported into vmcoreinfo? Ot= herwise, do you happen to know how to walk through the log_buf and get all kernel logs fr= om vmcore? Thanks. Lianbo > - VMCOREINFO_SYMBOL(log_first_idx); > - VMCOREINFO_SYMBOL(clear_idx); > - VMCOREINFO_SYMBOL(log_next_idx); > /* > - * Export struct printk_log size and field offsets. User space tools = can > - * parse it and detect any changes to structure down the line. > + * Export struct printk_info size and field offsets. User space tools > + * can parse it and detect any changes to structure down the line. > */ > - VMCOREINFO_STRUCT_SIZE(printk_log); > - VMCOREINFO_OFFSET(printk_log, ts_nsec); > - VMCOREINFO_OFFSET(printk_log, len); > - VMCOREINFO_OFFSET(printk_log, text_len); > - VMCOREINFO_OFFSET(printk_log, dict_len); > -#ifdef CONFIG_PRINTK_CALLER > - VMCOREINFO_OFFSET(printk_log, caller_id); > -#endif > + VMCOREINFO_STRUCT_SIZE(printk_info); > + VMCOREINFO_OFFSET(printk_info, seq); > + VMCOREINFO_OFFSET(printk_info, ts_nsec); > + VMCOREINFO_OFFSET(printk_info, text_len); > + VMCOREINFO_OFFSET(printk_info, dict_len); > + VMCOREINFO_OFFSET(printk_info, caller_id); > } > #endif > =20 > @@ -1146,11 +1007,55 @@ static void __init log_buf_add_cpu(void) > static inline void log_buf_add_cpu(void) {} > #endif /* CONFIG_SMP */ > =20 > +static unsigned int __init add_to_rb(struct printk_ringbuffer *rb, > + struct printk_record *r) > +{ > + struct printk_info info; > + struct printk_record dest_r =3D { > + .info =3D &info, > + .text_buf_size =3D r->info->text_len, > + .dict_buf_size =3D r->info->dict_len, > + }; > + struct prb_reserved_entry e; > + > + if (!prb_reserve(&e, rb, &dest_r)) > + return 0; > + > + memcpy(&dest_r.text_buf[0], &r->text_buf[0], dest_r.text_buf_size); > + if (dest_r.dict_buf) { > + memcpy(&dest_r.dict_buf[0], &r->dict_buf[0], > + dest_r.dict_buf_size); > + } > + dest_r.info->facility =3D r->info->facility; > + dest_r.info->level =3D r->info->level; > + dest_r.info->flags =3D r->info->flags; > + dest_r.info->ts_nsec =3D r->info->ts_nsec; > + dest_r.info->caller_id =3D r->info->caller_id; > + > + prb_commit(&e); > + > + return prb_record_text_space(&e); > +} > + > +static char setup_text_buf[CONSOLE_EXT_LOG_MAX] __initdata; > +static char setup_dict_buf[CONSOLE_EXT_LOG_MAX] __initdata; > + > void __init setup_log_buf(int early) > { > + struct prb_desc *new_descs; > + struct printk_info info; > + struct printk_record r =3D { > + .info =3D &info, > + .text_buf =3D &setup_text_buf[0], > + .dict_buf =3D &setup_dict_buf[0], > + .text_buf_size =3D sizeof(setup_text_buf), > + .dict_buf_size =3D sizeof(setup_dict_buf), > + }; > unsigned long flags; > + char *new_dict_buf; > char *new_log_buf; > unsigned int free; > + u64 seq; > =20 > if (log_buf !=3D __log_buf) > return; > @@ -1163,17 +1068,46 @@ void __init setup_log_buf(int early) > =20 > new_log_buf =3D memblock_alloc(new_log_buf_len, LOG_ALIGN); > if (unlikely(!new_log_buf)) { > - pr_err("log_buf_len: %lu bytes not available\n", > + pr_err("log_buf_len: %lu text bytes not available\n", > new_log_buf_len); > return; > } > =20 > + new_dict_buf =3D memblock_alloc(new_log_buf_len, LOG_ALIGN); > + if (unlikely(!new_dict_buf)) { > + /* dictionary failure is allowed */ > + pr_err("log_buf_len: %lu dict bytes not available\n", > + new_log_buf_len); > + } > + > + new_descs =3D memblock_alloc((new_log_buf_len >> PRB_AVGBITS) * > + sizeof(struct prb_desc), LOG_ALIGN); > + if (unlikely(!new_descs)) { > + pr_err("log_buf_len: %lu desc bytes not available\n", > + new_log_buf_len >> PRB_AVGBITS); > + if (new_dict_buf) > + memblock_free(__pa(new_dict_buf), new_log_buf_len); > + memblock_free(__pa(new_log_buf), new_log_buf_len); > + return; > + } > + > logbuf_lock_irqsave(flags); > + > + prb_init(&printk_rb_dynamic, > + new_log_buf, bits_per(new_log_buf_len) - 1, > + new_dict_buf, bits_per(new_log_buf_len) - 1, > + new_descs, (bits_per(new_log_buf_len) - 1) - PRB_AVGBITS); > + > log_buf_len =3D new_log_buf_len; > log_buf =3D new_log_buf; > new_log_buf_len =3D 0; > - free =3D __LOG_BUF_LEN - log_next_idx; > - memcpy(log_buf, __log_buf, __LOG_BUF_LEN); > + > + free =3D __LOG_BUF_LEN; > + prb_for_each_record(0, &printk_rb_static, seq, &r) > + free -=3D add_to_rb(&printk_rb_dynamic, &r); > + > + prb =3D &printk_rb_dynamic; > + > logbuf_unlock_irqrestore(flags); > =20 > pr_info("log_buf_len: %u bytes\n", log_buf_len); > @@ -1285,18 +1219,18 @@ static size_t print_caller(u32 id, char *buf) > #define print_caller(id, buf) 0 > #endif > =20 > -static size_t print_prefix(const struct printk_log *msg, bool syslog, > - bool time, char *buf) > +static size_t info_print_prefix(const struct printk_info *info, bool = syslog, > + bool time, char *buf) > { > size_t len =3D 0; > =20 > if (syslog) > - len =3D print_syslog((msg->facility << 3) | msg->level, buf); > + len =3D print_syslog((info->facility << 3) | info->level, buf); > =20 > if (time) > - len +=3D print_time(msg->ts_nsec, buf + len); > + len +=3D print_time(info->ts_nsec, buf + len); > =20 > - len +=3D print_caller(msg->caller_id, buf + len); > + len +=3D print_caller(info->caller_id, buf + len); > =20 > if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) { > buf[len++] =3D ' '; > @@ -1306,14 +1240,15 @@ static size_t print_prefix(const struct printk_= log *msg, bool syslog, > return len; > } > =20 > -static size_t msg_print_text(const struct printk_log *msg, bool syslog= , > - bool time, char *buf, size_t size) > +static size_t record_print_text(const struct printk_record *r, bool sy= slog, > + bool time, char *buf, size_t size) > { > - const char *text =3D log_text(msg); > - size_t text_size =3D msg->text_len; > + const char *text =3D &r->text_buf[0]; > + size_t text_size =3D r->info->text_len; > size_t len =3D 0; > char prefix[PREFIX_MAX]; > - const size_t prefix_len =3D print_prefix(msg, syslog, time, prefix); > + const size_t prefix_len =3D info_print_prefix(r->info, syslog, time, > + prefix); > =20 > do { > const char *next =3D memchr(text, '\n', text_size); > @@ -1347,10 +1282,94 @@ static size_t msg_print_text(const struct print= k_log *msg, bool syslog, > return len; > } > =20 > +static size_t record_print_text_inline(struct printk_record *r, bool s= yslog, > + bool time) > +{ > + size_t text_len =3D r->info->text_len; > + size_t buf_size =3D r->text_buf_size; > + char *text =3D r->text_buf; > + char prefix[PREFIX_MAX]; > + bool truncated =3D false; > + size_t prefix_len; > + size_t len =3D 0; > + > + prefix_len =3D info_print_prefix(r->info, syslog, time, prefix); > + > + if (!text) { > + /* SYSLOG_ACTION_* buffer size only calculation */ > + unsigned int line_count =3D 1; > + > + if (r->text_line_count) > + line_count =3D *(r->text_line_count); > + /* > + * Each line will be preceded with a prefix. The intermediate > + * newlines are already within the text, but a final trailing > + * newline will be added. > + */ > + return ((prefix_len * line_count) + r->info->text_len + 1); > + } > + > + /* > + * Add the prefix for each line by shifting the rest of the text to > + * make room for the prefix. If the buffer is not large enough for al= l > + * the prefixes, then drop the trailing text and report the largest > + * length that includes full lines with their prefixes. > + */ > + while (text_len) { > + size_t line_len; > + char *next; > + > + next =3D memchr(text, '\n', text_len); > + if (next) { > + line_len =3D next - text; > + } else { > + /* > + * If the text has been truncated, assume this line > + * was truncated and do not include this text. > + */ > + if (truncated) > + break; > + line_len =3D text_len; > + } > + > + /* > + * Is there enough buffer available to shift this line > + * (and add a newline at the end)? > + */ > + if (len + prefix_len + line_len >=3D buf_size) > + break; > + > + /* > + * Is there enough buffer available to shift all remaining > + * text (and add a newline at the end)? > + */ > + if (len + prefix_len + text_len >=3D buf_size) { > + text_len =3D (buf_size - len) - prefix_len; > + truncated =3D true; > + } > + > + memmove(text + prefix_len, text, text_len); > + memcpy(text, prefix, prefix_len); > + > + text +=3D prefix_len + line_len; > + text_len -=3D line_len; > + > + if (text_len) { > + text_len--; > + text++; > + } else { > + *text =3D '\n'; > + } > + > + len +=3D prefix_len + line_len + 1; > + } > + > + return len; > +} > + > static int syslog_print(char __user *buf, int size) > { > char *text; > - struct printk_log *msg; > int len =3D 0; > =20 > text =3D kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); > @@ -1362,16 +1381,15 @@ static int syslog_print(char __user *buf, int s= ize) > size_t skip; > =20 > logbuf_lock_irq(); > - if (syslog_seq < log_first_seq) { > - /* messages are gone, move to first one */ > - syslog_seq =3D log_first_seq; > - syslog_idx =3D log_first_idx; > - syslog_partial =3D 0; > - } > - if (syslog_seq =3D=3D log_next_seq) { > + if (!prb_read_valid(prb, syslog_seq, &syslog_record)) { > logbuf_unlock_irq(); > break; > } > + if (syslog_record.info->seq !=3D syslog_seq) { > + /* messages are gone, move to first one */ > + syslog_seq =3D syslog_record.info->seq; > + syslog_partial =3D 0; > + } > =20 > /* > * To keep reading/counting partial line consistent, > @@ -1381,13 +1399,11 @@ static int syslog_print(char __user *buf, int s= ize) > syslog_time =3D printk_time; > =20 > skip =3D syslog_partial; > - msg =3D log_from_idx(syslog_idx); > - n =3D msg_print_text(msg, true, syslog_time, text, > - LOG_LINE_MAX + PREFIX_MAX); > + n =3D record_print_text(&syslog_record, true, syslog_time, text, > + LOG_LINE_MAX + PREFIX_MAX); > if (n - syslog_partial <=3D size) { > /* message fits into buffer, move forward */ > - syslog_idx =3D log_next(syslog_idx); > - syslog_seq++; > + syslog_seq =3D syslog_record.info->seq + 1; > n -=3D syslog_partial; > syslog_partial =3D 0; > } else if (!len){ > @@ -1420,9 +1436,7 @@ static int syslog_print_all(char __user *buf, int= size, bool clear) > { > char *text; > int len =3D 0; > - u64 next_seq; > u64 seq; > - u32 idx; > bool time; > =20 > text =3D kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL); > @@ -1435,38 +1449,30 @@ static int syslog_print_all(char __user *buf, i= nt size, bool clear) > * Find first record that fits, including all following records, > * into the user-provided buffer for this dump. > */ > - seq =3D clear_seq; > - idx =3D clear_idx; > - while (seq < log_next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > - > - len +=3D msg_print_text(msg, true, time, NULL, 0); > - idx =3D log_next(idx); > - seq++; > - } > + prb_for_each_record(clear_seq, prb, seq, &syslog_record) > + len +=3D record_print_text(&syslog_record, true, time, NULL, 0); > =20 > /* move first record forward until length fits into the buffer */ > - seq =3D clear_seq; > - idx =3D clear_idx; > - while (len > size && seq < log_next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > - > - len -=3D msg_print_text(msg, true, time, NULL, 0); > - idx =3D log_next(idx); > - seq++; > + prb_for_each_record(clear_seq, prb, seq, &syslog_record) { > + if (len <=3D size) > + break; > + len -=3D record_print_text(&syslog_record, true, time, NULL, 0); > } > =20 > - /* last message fitting into this dump */ > - next_seq =3D log_next_seq; > - > len =3D 0; > - while (len >=3D 0 && seq < next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > - int textlen =3D msg_print_text(msg, true, time, text, > - LOG_LINE_MAX + PREFIX_MAX); > + prb_for_each_record(seq, prb, seq, &syslog_record) { > + int textlen; > =20 > - idx =3D log_next(idx); > - seq++; > + if (len < 0) > + break; > + > + textlen =3D record_print_text(&syslog_record, true, time, text, > + LOG_LINE_MAX + PREFIX_MAX); > + > + if (len + textlen > size) { > + seq--; > + break; > + } > =20 > logbuf_unlock_irq(); > if (copy_to_user(buf + len, text, textlen)) > @@ -1474,18 +1480,10 @@ static int syslog_print_all(char __user *buf, i= nt size, bool clear) > else > len +=3D textlen; > logbuf_lock_irq(); > - > - if (seq < log_first_seq) { > - /* messages are gone, move to next one */ > - seq =3D log_first_seq; > - idx =3D log_first_idx; > - } > } > =20 > - if (clear) { > - clear_seq =3D log_next_seq; > - clear_idx =3D log_next_idx; > - } > + if (clear) > + clear_seq =3D seq; > logbuf_unlock_irq(); > =20 > kfree(text); > @@ -1495,8 +1493,7 @@ static int syslog_print_all(char __user *buf, int= size, bool clear) > static void syslog_clear(void) > { > logbuf_lock_irq(); > - clear_seq =3D log_next_seq; > - clear_idx =3D log_next_idx; > + clear_seq =3D prb_next_seq(prb); > logbuf_unlock_irq(); > } > =20 > @@ -1523,7 +1520,7 @@ int do_syslog(int type, char __user *buf, int len= , int source) > if (!access_ok(buf, len)) > return -EFAULT; > error =3D wait_event_interruptible(log_wait, > - syslog_seq !=3D log_next_seq); > + prb_read_valid(prb, syslog_seq, NULL)); > if (error) > return error; > error =3D syslog_print(buf, len); > @@ -1572,10 +1569,9 @@ int do_syslog(int type, char __user *buf, int le= n, int source) > /* Number of chars in the log buffer */ > case SYSLOG_ACTION_SIZE_UNREAD: > logbuf_lock_irq(); > - if (syslog_seq < log_first_seq) { > + if (syslog_seq < prb_first_seq(prb)) { > /* messages are gone, move to first one */ > - syslog_seq =3D log_first_seq; > - syslog_idx =3D log_first_idx; > + syslog_seq =3D prb_first_seq(prb); > syslog_partial =3D 0; > } > if (source =3D=3D SYSLOG_FROM_PROC) { > @@ -1584,20 +1580,17 @@ int do_syslog(int type, char __user *buf, int l= en, int source) > * for pending data, not the size; return the count of > * records, not the length. > */ > - error =3D log_next_seq - syslog_seq; > + error =3D prb_next_seq(prb) - syslog_seq; > } else { > - u64 seq =3D syslog_seq; > - u32 idx =3D syslog_idx; > bool time =3D syslog_partial ? syslog_time : printk_time; > + u64 seq; > =20 > - while (seq < log_next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > - > - error +=3D msg_print_text(msg, true, time, NULL, > - 0); > + prb_for_each_record(syslog_seq, prb, seq, > + &syslog_record) { > + error +=3D record_print_text(&syslog_record, > + true, time, > + NULL, 0); > time =3D printk_time; > - idx =3D log_next(idx); > - seq++; > } > error -=3D syslog_partial; > } > @@ -1958,7 +1951,6 @@ asmlinkage int vprintk_emit(int facility, int lev= el, > int printed_len; > bool in_sched =3D false, pending_output; > unsigned long flags; > - u64 curr_log_seq; > =20 > /* Suppress unimportant messages after panic happens */ > if (unlikely(suppress_printk)) > @@ -1974,9 +1966,9 @@ asmlinkage int vprintk_emit(int facility, int lev= el, > =20 > /* This stops the holder of console_sem just where we want him */ > logbuf_lock_irqsave(flags); > - curr_log_seq =3D log_next_seq; > + pending_output =3D !prb_read_valid(prb, console_seq, NULL); > printed_len =3D vprintk_store(facility, level, dict, dictlen, fmt, ar= gs); > - pending_output =3D (curr_log_seq !=3D log_next_seq); > + pending_output &=3D prb_read_valid(prb, console_seq, NULL); > logbuf_unlock_irqrestore(flags); > =20 > /* If called from the scheduler, we can not call up(). */ > @@ -2066,21 +2058,30 @@ EXPORT_SYMBOL(printk); > #define PREFIX_MAX 0 > #define printk_time false > =20 > +#define prb_read_valid(rb, seq, r) false > +#define prb_first_seq(rb) 0 > + > static u64 syslog_seq; > -static u32 syslog_idx; > static u64 console_seq; > -static u32 console_idx; > static u64 exclusive_console_stop_seq; > -static u64 log_first_seq; > -static u32 log_first_idx; > -static u64 log_next_seq; > -static char *log_text(const struct printk_log *msg) { return NULL; } > -static char *log_dict(const struct printk_log *msg) { return NULL; } > -static struct printk_log *log_from_idx(u32 idx) { return NULL; } > -static u32 log_next(u32 idx) { return 0; } > -static ssize_t msg_print_ext_header(char *buf, size_t size, > - struct printk_log *msg, > - u64 seq) { return 0; } > +struct printk_record console_record; > + > +static size_t record_print_text(const struct printk_record *r, bool sy= slog, > + bool time, char *buf, > + size_t size) > +{ > + return 0; > +} > +static size_t record_print_text_inline(const struct printk_record *r, > + bool syslog, bool time) > +{ > + return 0; > +} > +static ssize_t info_print_ext_header(char *buf, size_t size, > + struct printk_info *info) > +{ > + return 0; > +} > static ssize_t msg_print_ext_body(char *buf, size_t size, > char *dict, size_t dict_len, > char *text, size_t text_len) { return 0; } > @@ -2088,8 +2089,6 @@ static void console_lock_spinning_enable(void) { = } > static int console_lock_spinning_disable_and_check(void) { return 0; } > static void call_console_drivers(const char *ext_text, size_t ext_len, > const char *text, size_t len) {} > -static size_t msg_print_text(const struct printk_log *msg, bool syslog= , > - bool time, char *buf, size_t size) { return 0; } > static bool suppress_message_printing(int level) { return false; } > =20 > #endif /* CONFIG_PRINTK */ > @@ -2406,35 +2405,28 @@ void console_unlock(void) > } > =20 > for (;;) { > - struct printk_log *msg; > size_t ext_len =3D 0; > - size_t len; > + size_t len =3D 0; > =20 > printk_safe_enter_irqsave(flags); > raw_spin_lock(&logbuf_lock); > - if (console_seq < log_first_seq) { > +skip: > + if (!prb_read_valid(prb, console_seq, &console_record)) > + break; > + > + if (console_seq < console_record.info->seq) { > len =3D sprintf(text, > "** %llu printk messages dropped **\n", > - log_first_seq - console_seq); > - > - /* messages are gone, move to first one */ > - console_seq =3D log_first_seq; > - console_idx =3D log_first_idx; > - } else { > - len =3D 0; > + console_record.info->seq - console_seq); > } > -skip: > - if (console_seq =3D=3D log_next_seq) > - break; > + console_seq =3D console_record.info->seq; > =20 > - msg =3D log_from_idx(console_idx); > - if (suppress_message_printing(msg->level)) { > + if (suppress_message_printing(console_record.info->level)) { > /* > * Skip record we have buffered and already printed > * directly to the console when we received it, and > * record that has level above the console loglevel. > */ > - console_idx =3D log_next(console_idx); > console_seq++; > goto skip; > } > @@ -2445,19 +2437,20 @@ void console_unlock(void) > exclusive_console =3D NULL; > } > =20 > - len +=3D msg_print_text(msg, > + len +=3D record_print_text(&console_record, > console_msg_format & MSG_FORMAT_SYSLOG, > printk_time, text + len, sizeof(text) - len); > if (nr_ext_console_drivers) { > - ext_len =3D msg_print_ext_header(ext_text, > + ext_len =3D info_print_ext_header(ext_text, > sizeof(ext_text), > - msg, console_seq); > + console_record.info); > ext_len +=3D msg_print_ext_body(ext_text + ext_len, > sizeof(ext_text) - ext_len, > - log_dict(msg), msg->dict_len, > - log_text(msg), msg->text_len); > + &console_record.dict_buf[0], > + console_record.info->dict_len, > + &console_record.text_buf[0], > + console_record.info->text_len); > } > - console_idx =3D log_next(console_idx); > console_seq++; > raw_spin_unlock(&logbuf_lock); > =20 > @@ -2497,7 +2490,7 @@ void console_unlock(void) > * flush, no worries. > */ > raw_spin_lock(&logbuf_lock); > - retry =3D console_seq !=3D log_next_seq; > + retry =3D prb_read_valid(prb, console_seq, NULL); > raw_spin_unlock(&logbuf_lock); > printk_safe_exit_irqrestore(flags); > =20 > @@ -2566,8 +2559,7 @@ void console_flush_on_panic(enum con_flush_mode m= ode) > unsigned long flags; > =20 > logbuf_lock_irqsave(flags); > - console_seq =3D log_first_seq; > - console_idx =3D log_first_idx; > + console_seq =3D prb_first_seq(prb); > logbuf_unlock_irqrestore(flags); > } > console_unlock(); > @@ -2770,8 +2762,6 @@ void register_console(struct console *newcon) > * for us. > */ > logbuf_lock_irqsave(flags); > - console_seq =3D syslog_seq; > - console_idx =3D syslog_idx; > /* > * We're about to replay the log buffer. Only do this to the > * just-registered console to avoid excessive message spam to > @@ -2783,6 +2773,7 @@ void register_console(struct console *newcon) > */ > exclusive_console =3D newcon; > exclusive_console_stop_seq =3D console_seq; > + console_seq =3D syslog_seq; > logbuf_unlock_irqrestore(flags); > } > console_unlock(); > @@ -3127,9 +3118,7 @@ void kmsg_dump(enum kmsg_dump_reason reason) > =20 > logbuf_lock_irqsave(flags); > dumper->cur_seq =3D clear_seq; > - dumper->cur_idx =3D clear_idx; > - dumper->next_seq =3D log_next_seq; > - dumper->next_idx =3D log_next_idx; > + dumper->next_seq =3D prb_next_seq(prb); > logbuf_unlock_irqrestore(flags); > =20 > /* invoke dumper which will iterate over records */ > @@ -3163,28 +3152,29 @@ void kmsg_dump(enum kmsg_dump_reason reason) > bool kmsg_dump_get_line_nolock(struct kmsg_dumper *dumper, bool syslog= , > char *line, size_t size, size_t *len) > { > - struct printk_log *msg; > + struct printk_info info; > + struct printk_record r =3D { > + .info =3D &info, > + .text_buf =3D line, > + .text_buf_size =3D size, > + }; > + unsigned int line_count; > size_t l =3D 0; > bool ret =3D false; > =20 > if (!dumper->active) > goto out; > =20 > - if (dumper->cur_seq < log_first_seq) { > - /* messages are gone, move to first available one */ > - dumper->cur_seq =3D log_first_seq; > - dumper->cur_idx =3D log_first_idx; > - } > + /* Count text lines instead of reading text? */ > + if (!line) > + r.text_line_count =3D &line_count; > =20 > - /* last entry */ > - if (dumper->cur_seq >=3D log_next_seq) > + if (!prb_read_valid(prb, dumper->cur_seq, &r)) > goto out; > =20 > - msg =3D log_from_idx(dumper->cur_idx); > - l =3D msg_print_text(msg, syslog, printk_time, line, size); > + l =3D record_print_text_inline(&r, syslog, printk_time); > =20 > - dumper->cur_idx =3D log_next(dumper->cur_idx); > - dumper->cur_seq++; > + dumper->cur_seq =3D r.info->seq + 1; > ret =3D true; > out: > if (len) > @@ -3245,23 +3235,27 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_line); > bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog, > char *buf, size_t size, size_t *len) > { > + struct printk_info info; > + unsigned int line_count; > + /* initially, only count text lines */ > + struct printk_record r =3D { > + .info =3D &info, > + .text_line_count =3D &line_count, > + }; > unsigned long flags; > u64 seq; > - u32 idx; > u64 next_seq; > - u32 next_idx; > size_t l =3D 0; > bool ret =3D false; > bool time =3D printk_time; > =20 > - if (!dumper->active) > + if (!dumper->active || !buf || !size) > goto out; > =20 > logbuf_lock_irqsave(flags); > - if (dumper->cur_seq < log_first_seq) { > + if (dumper->cur_seq < prb_first_seq(prb)) { > /* messages are gone, move to first available one */ > - dumper->cur_seq =3D log_first_seq; > - dumper->cur_idx =3D log_first_idx; > + dumper->cur_seq =3D prb_first_seq(prb); > } > =20 > /* last entry */ > @@ -3272,41 +3266,43 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *d= umper, bool syslog, > =20 > /* calculate length of entire buffer */ > seq =3D dumper->cur_seq; > - idx =3D dumper->cur_idx; > - while (seq < dumper->next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > - > - l +=3D msg_print_text(msg, true, time, NULL, 0); > - idx =3D log_next(idx); > - seq++; > + while (prb_read_valid(prb, seq, &r)) { > + if (r.info->seq >=3D dumper->next_seq) > + break; > + l +=3D record_print_text_inline(&r, true, time); > + seq =3D r.info->seq + 1; > } > =20 > /* move first record forward until length fits into the buffer */ > seq =3D dumper->cur_seq; > - idx =3D dumper->cur_idx; > - while (l >=3D size && seq < dumper->next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > - > - l -=3D msg_print_text(msg, true, time, NULL, 0); > - idx =3D log_next(idx); > - seq++; > + while (l >=3D size && prb_read_valid(prb, seq, &r)) { > + if (r.info->seq >=3D dumper->next_seq) > + break; > + l -=3D record_print_text_inline(&r, true, time); > + seq =3D r.info->seq + 1; > } > =20 > /* last message in next interation */ > next_seq =3D seq; > - next_idx =3D idx; > + > + /* actually read data into the buffer now */ > + r.text_buf =3D buf; > + r.text_buf_size =3D size; > + r.text_line_count =3D NULL; > =20 > l =3D 0; > - while (seq < dumper->next_seq) { > - struct printk_log *msg =3D log_from_idx(idx); > + while (prb_read_valid(prb, seq, &r)) { > + if (r.info->seq >=3D dumper->next_seq) > + break; > + > + l +=3D record_print_text_inline(&r, syslog, time); > + r.text_buf =3D buf + l; > + r.text_buf_size =3D size - l; > =20 > - l +=3D msg_print_text(msg, syslog, time, buf + l, size - l); > - idx =3D log_next(idx); > - seq++; > + seq =3D r.info->seq + 1; > } > =20 > dumper->next_seq =3D next_seq; > - dumper->next_idx =3D next_idx; > ret =3D true; > logbuf_unlock_irqrestore(flags); > out: > @@ -3329,9 +3325,7 @@ EXPORT_SYMBOL_GPL(kmsg_dump_get_buffer); > void kmsg_dump_rewind_nolock(struct kmsg_dumper *dumper) > { > dumper->cur_seq =3D clear_seq; > - dumper->cur_idx =3D clear_idx; > - dumper->next_seq =3D log_next_seq; > - dumper->next_idx =3D log_next_idx; > + dumper->next_seq =3D prb_next_seq(prb); > } > =20 > /** >=20