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SubjectRe: [PATCH 2/2] printk: use the lockless ringbuffer
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在 2020年01月29日 00:19, John Ogness 写道:
> 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.
>
> Changes that exist due to the ringbuffer replacement:
>
> - The VMCOREINFO has been updated for the new structures.
>
> - 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.
>
> - 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.
>
> Signed-off-by: John Ogness <john.ogness@linutronix.de>
> ---
> include/linux/kmsg_dump.h | 2 -
> kernel/printk/Makefile | 1 +
> kernel/printk/printk.c | 836 +++++++++++++++++++-------------------
> 3 files changed, 416 insertions(+), 423 deletions(-)
>
> 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;
>
> /* 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 = printk.o
> obj-$(CONFIG_PRINTK) += printk_safe.o
> obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o
> +obj-$(CONFIG_PRINTK) += 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 <trace/events/printk.h>
>
> +#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 = MSG_FORMAT_DEFAULT;
>
> /*
> - * The printk log buffer consists of a chain of concatenated variable
> - * length records. Every record starts with a record header, containing
> - * 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 record
> + * 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 == 0 for the next message
> - * indicates a wrap-around to the beginning of the buffer.
> - *
> - * Every record carries the monotonic timestamp in microseconds, as well as
> - * the standard userspace syslog level and syslog facility. The usual
> + * Every record meta-data carries the monotonic timestamp in microseconds, as
> + * well as the standard userspace syslog level and syslog facility. The usual
> * kernel messages use LOG_KERN; userspace-injected messages always carry
> * a matching syslog facility, by default LOG_USER. The origin of every
> * 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 message
> - * is not terminated.
> + * The human readable log message of a record is available in @text, the length
> + * of the message text in @text_len. The stored message is not terminated.
> *
> - * Optionally, a message can carry a dictionary of properties (key/value pairs),
> - * to provide userspace with a machine-readable message context.
> + * Optionally, a record can carry a dictionary of properties (key/value pairs),
> + * to provide userspace with a machine-readable message context. The length of
> + * the dictionary is available in @dict_len. The dictionary is not terminated.
> *
> * Examples for well-defined, commonly used property names are:
> * DEVICE=b12:8 device identifier
> @@ -331,21 +324,19 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
> * follows directly after a '=' character. Every property is terminated 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 (level)
> - * 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=b8:2\0D"
> - * 52 49 56 45 52 3d 62 75 "RIVER=bu"
> - * 67 "g"
> - * 0032 00 00 00 padding to next message header
> - *
> - * The 'struct printk_log' buffer header must never be directly exported to
> + * Example of record values:
> + * record.text_buf = "it's a line" (unterminated)
> + * record.dict_buf = "DEVICE=b8:2\0DRIVER=bug" (unterminated)
> + * record.info.seq = 56
> + * record.info.ts_sec = 36863
> + * record.info.text_len = 11
> + * record.info.dict_len = 22
> + * record.info.facility = 0 (LOG_KERN)
> + * record.info.flags = 0
> + * record.info.level = 3 (LOG_ERR)
> + * record.info.caller_id = 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 = 8, /* text is a fragment of a continuation line */
> };
>
> -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);
>
> /* 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);
>
> /* the next printk record to read after the last 'clear' command */
> static u64 clear_seq;
> -static u32 clear_idx;
>
> #ifdef CONFIG_PRINTK_CALLER
> #define PREFIX_MAX 48
> @@ -453,13 +418,28 @@ static u32 clear_idx;
> #define LOG_FACILITY(v) ((v) >> 3 & 0xff)
>
> /* 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 = __log_buf;
> static u32 log_buf_len = __LOG_BUF_LEN;
>
> +/*
> + * 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 enough).
> + * 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 = &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;
> }
>
> -/* 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 = (struct printk_log *)(log_buf + idx);
> -
> - /*
> - * A length == 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 = (struct printk_log *)(log_buf + idx);
> -
> - /* length == 0 indicates the end of the buffer; wrap */
> - /*
> - * A length == 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 = (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 = max(log_buf_len - log_next_idx, log_first_idx);
> - else
> - free = log_first_idx - log_next_idx;
> -
> - /*
> - * We need space also for an empty header that signalizes wrapping
> - * of the buffer.
> - */
> - return free >= 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 = log_next(log_first_idx);
> - log_first_seq++;
> - }
> -
> - if (clear_seq < log_first_seq) {
> - clear_seq = log_first_seq;
> - clear_idx = log_first_idx;
> - }
> -
> - /* sequence numbers are equal, so the log buffer is empty */
> - if (logbuf_has_space(msg_size, log_first_seq == 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 = sizeof(struct printk_log) + text_len + dict_len;
> - *pad_len = (-size) & (LOG_ALIGN - 1);
> - size += *pad_len;
> -
> - return size;
> -}
> -
> /*
> * Define how much of the log buffer we could take at maximum. The value
> * must be greater than two. Note that only half of the buffer is available
> @@ -582,22 +460,26 @@ static u32 msg_used_size(u16 text_len, u16 dict_len, u32 *pad_len)
> #define MAX_LOG_TAKE_PART 4
> static const char trunc_msg[] = "<truncated>";
>
> -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 = log_buf_len / MAX_LOG_TAKE_PART;
> +
> if (*text_len > max_text_len)
> *text_len = max_text_len;
> - /* enable the warning message */
> +
> + /* enable the warning message (if there is room) */
> *trunc_msg_len = strlen(trunc_msg);
> + if (*text_len >= *trunc_msg_len)
> + *text_len -= *trunc_msg_len;
> + else
> + *trunc_msg_len = 0;
> +
> /* disable the "dict" completely */
> *dict_len = 0;
> - /* compute the size again, count also the warning message */
> - return msg_used_size(*text_len + *trunc_msg_len, 0, pad_len);
> }
>
> /* 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 = 0;
>
> - /* number of '\0' padding bytes to next message */
> - size = msg_used_size(text_len, dict_len, &pad_len);
> + r.text_buf_size = text_len;
> + r.dict_buf_size = dict_len;
>
> - if (log_make_free_space(size)) {
> + if (!prb_reserve(&e, prb, &r)) {
> /* truncate the message if it is too long for empty buffer */
> - size = truncate_msg(&text_len, &trunc_msg_len,
> - &dict_len, &pad_len);
> + truncate_msg(&text_len, &trunc_msg_len, &dict_len);
> + r.text_buf_size = text_len + trunc_msg_len;
> + r.dict_buf_size = 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;
> }
>
> - 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 == 0
> - * to signify a wrap around.
> - */
> - memset(log_buf + log_next_idx, 0, sizeof(struct printk_log));
> - log_next_idx = 0;
> - }
> -
> /* fill message */
> - msg = (struct printk_log *)(log_buf + log_next_idx);
> - memcpy(log_text(msg), text, text_len);
> - msg->text_len = text_len;
> - if (trunc_msg_len) {
> - memcpy(log_text(msg) + text_len, trunc_msg, trunc_msg_len);
> - msg->text_len += trunc_msg_len;
> - }
> - memcpy(log_dict(msg), dict, dict_len);
> - msg->dict_len = dict_len;
> - msg->facility = facility;
> - msg->level = level & 7;
> - msg->flags = 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 = facility;
> + r.info->level = level & 7;
> + r.info->flags = flags & 0x1f;
> if (ts_nsec > 0)
> - msg->ts_nsec = ts_nsec;
> + r.info->ts_nsec = ts_nsec;
> else
> - msg->ts_nsec = local_clock();
> -#ifdef CONFIG_PRINTK_CALLER
> - msg->caller_id = caller_id;
> -#endif
> - memset(log_dict(msg) + dict_len, 0, pad_len);
> - msg->len = size;
> + r.info->ts_nsec = local_clock();
> + r.info->caller_id = caller_id;
>
> /* insert message */
> - log_next_idx += msg->len;
> - log_next_seq++;
> + prb_commit(&e);
>
> - return msg->text_len;
> + return text_len;
> }
>
> int dmesg_restrict = IS_ENABLED(CONFIG_SECURITY_DMESG_RESTRICT);
> @@ -711,13 +575,13 @@ static void append_char(char **pp, char *e, char c)
> *(*pp)++ = c;
> }
>
> -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 = msg->ts_nsec;
> + u64 ts_usec = info->ts_nsec;
> char caller[20];
> #ifdef CONFIG_PRINTK_CALLER
> - u32 id = msg->caller_id;
> + u32 id = info->caller_id;
>
> snprintf(caller, sizeof(caller), ",caller=%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);
>
> 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);
> }
>
> 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;
> };
>
> 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 = file->private_data;
> - struct printk_log *msg;
> + struct printk_record *r = &user->record;
> size_t len;
> ssize_t ret;
>
> @@ -881,7 +749,7 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
> return ret;
>
> logbuf_lock_irq();
> - while (user->seq == log_next_seq) {
> + if (!prb_read_valid(prb, user->seq, r)) {
> if (file->f_flags & O_NONBLOCK) {
> ret = -EAGAIN;
> logbuf_unlock_irq();
> @@ -890,30 +758,26 @@ static ssize_t devkmsg_read(struct file *file, char __user *buf,
>
> logbuf_unlock_irq();
> ret = wait_event_interruptible(log_wait,
> - user->seq != log_next_seq);
> + prb_read_valid(prb, user->seq, r));
> if (ret)
> goto out;
> logbuf_lock_irq();
> }
>
> - if (user->seq < log_first_seq) {
> - /* our last seen message is gone, return error and reset */
> - user->idx = log_first_idx;
> - user->seq = log_first_seq;
> + if (user->seq < r->info->seq) {
> + /* the expected message is gone, return error and reset */
> + user->seq = r->info->seq;
> ret = -EPIPE;
> logbuf_unlock_irq();
> goto out;
> }
>
> - msg = log_from_idx(user->idx);
> - len = msg_print_ext_header(user->buf, sizeof(user->buf),
> - msg, user->seq);
> + len = info_print_ext_header(user->buf, sizeof(user->buf), r->info);
> len += 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);
>
> - user->idx = log_next(user->idx);
> - user->seq++;
> + user->seq = r->info->seq + 1;
> logbuf_unlock_irq();
>
> if (len > count) {
> @@ -945,8 +809,7 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
> switch (whence) {
> case SEEK_SET:
> /* the first record */
> - user->idx = log_first_idx;
> - user->seq = log_first_seq;
> + user->seq = prb_first_seq(prb);
> break;
> case SEEK_DATA:
> /*
> @@ -954,13 +817,11 @@ static loff_t devkmsg_llseek(struct file *file, loff_t offset, int whence)
> * like issued by 'dmesg -c'. Reading /dev/kmsg itself
> * changes no global state, and does not clear anything.
> */
> - user->idx = clear_idx;
> user->seq = clear_seq;
> break;
> case SEEK_END:
> /* after the last record */
> - user->idx = log_next_idx;
> - user->seq = log_next_seq;
> + user->seq = prb_next_seq(prb);
> break;
> default:
> ret = -EINVAL;
> @@ -980,9 +841,9 @@ static __poll_t devkmsg_poll(struct file *file, poll_table *wait)
> poll_wait(file, &log_wait, wait);
>
> 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 = EPOLLIN|EPOLLRDNORM|EPOLLERR|EPOLLPRI;
> else
> ret = EPOLLIN|EPOLLRDNORM;
> @@ -1017,9 +878,14 @@ static int devkmsg_open(struct inode *inode, struct file *file)
>
> mutex_init(&user->lock);
>
> + user->record.info = &user->info;
> + user->record.text_buf = &user->text_buf[0];
> + user->record.text_buf_size = sizeof(user->text_buf);
> + user->record.dict_buf = &user->dict_buf[0];
> + user->record.dict_buf_size = sizeof(user->dict_buf);
> +
> logbuf_lock_irq();
> - user->idx = log_first_idx;
> - user->seq = log_first_seq;
> + user->seq = prb_first_seq(prb);
> logbuf_unlock_irq();
>
> file->private_data = 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 vmcoreinfo as follows:

+ VMCOREINFO_SYMBOL(prb);

Should the "prb"(printk tb static) symbol be exported into vmcoreinfo? Otherwise, do you
happen to know how to walk through the log_buf and get all kernel logs from 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
>
> @@ -1146,11 +1007,55 @@ static void __init log_buf_add_cpu(void)
> static inline void log_buf_add_cpu(void) {}
> #endif /* CONFIG_SMP */
>
> +static unsigned int __init add_to_rb(struct printk_ringbuffer *rb,
> + struct printk_record *r)
> +{
> + struct printk_info info;
> + struct printk_record dest_r = {
> + .info = &info,
> + .text_buf_size = r->info->text_len,
> + .dict_buf_size = 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 = r->info->facility;
> + dest_r.info->level = r->info->level;
> + dest_r.info->flags = r->info->flags;
> + dest_r.info->ts_nsec = r->info->ts_nsec;
> + dest_r.info->caller_id = 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 = {
> + .info = &info,
> + .text_buf = &setup_text_buf[0],
> + .dict_buf = &setup_dict_buf[0],
> + .text_buf_size = sizeof(setup_text_buf),
> + .dict_buf_size = sizeof(setup_dict_buf),
> + };
> unsigned long flags;
> + char *new_dict_buf;
> char *new_log_buf;
> unsigned int free;
> + u64 seq;
>
> if (log_buf != __log_buf)
> return;
> @@ -1163,17 +1068,46 @@ void __init setup_log_buf(int early)
>
> new_log_buf = 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;
> }
>
> + new_dict_buf = 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 = 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 = new_log_buf_len;
> log_buf = new_log_buf;
> new_log_buf_len = 0;
> - free = __LOG_BUF_LEN - log_next_idx;
> - memcpy(log_buf, __log_buf, __LOG_BUF_LEN);
> +
> + free = __LOG_BUF_LEN;
> + prb_for_each_record(0, &printk_rb_static, seq, &r)
> + free -= add_to_rb(&printk_rb_dynamic, &r);
> +
> + prb = &printk_rb_dynamic;
> +
> logbuf_unlock_irqrestore(flags);
>
> 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
>
> -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 = 0;
>
> if (syslog)
> - len = print_syslog((msg->facility << 3) | msg->level, buf);
> + len = print_syslog((info->facility << 3) | info->level, buf);
>
> if (time)
> - len += print_time(msg->ts_nsec, buf + len);
> + len += print_time(info->ts_nsec, buf + len);
>
> - len += print_caller(msg->caller_id, buf + len);
> + len += print_caller(info->caller_id, buf + len);
>
> if (IS_ENABLED(CONFIG_PRINTK_CALLER) || time) {
> buf[len++] = ' ';
> @@ -1306,14 +1240,15 @@ static size_t print_prefix(const struct printk_log *msg, bool syslog,
> return len;
> }
>
> -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 syslog,
> + bool time, char *buf, size_t size)
> {
> - const char *text = log_text(msg);
> - size_t text_size = msg->text_len;
> + const char *text = &r->text_buf[0];
> + size_t text_size = r->info->text_len;
> size_t len = 0;
> char prefix[PREFIX_MAX];
> - const size_t prefix_len = print_prefix(msg, syslog, time, prefix);
> + const size_t prefix_len = info_print_prefix(r->info, syslog, time,
> + prefix);
>
> do {
> const char *next = memchr(text, '\n', text_size);
> @@ -1347,10 +1282,94 @@ static size_t msg_print_text(const struct printk_log *msg, bool syslog,
> return len;
> }
>
> +static size_t record_print_text_inline(struct printk_record *r, bool syslog,
> + bool time)
> +{
> + size_t text_len = r->info->text_len;
> + size_t buf_size = r->text_buf_size;
> + char *text = r->text_buf;
> + char prefix[PREFIX_MAX];
> + bool truncated = false;
> + size_t prefix_len;
> + size_t len = 0;
> +
> + prefix_len = info_print_prefix(r->info, syslog, time, prefix);
> +
> + if (!text) {
> + /* SYSLOG_ACTION_* buffer size only calculation */
> + unsigned int line_count = 1;
> +
> + if (r->text_line_count)
> + line_count = *(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 all
> + * 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 = memchr(text, '\n', text_len);
> + if (next) {
> + line_len = 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 = text_len;
> + }
> +
> + /*
> + * Is there enough buffer available to shift this line
> + * (and add a newline at the end)?
> + */
> + if (len + prefix_len + line_len >= 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 >= buf_size) {
> + text_len = (buf_size - len) - prefix_len;
> + truncated = true;
> + }
> +
> + memmove(text + prefix_len, text, text_len);
> + memcpy(text, prefix, prefix_len);
> +
> + text += prefix_len + line_len;
> + text_len -= line_len;
> +
> + if (text_len) {
> + text_len--;
> + text++;
> + } else {
> + *text = '\n';
> + }
> +
> + len += prefix_len + line_len + 1;
> + }
> +
> + return len;
> +}
> +
> static int syslog_print(char __user *buf, int size)
> {
> char *text;
> - struct printk_log *msg;
> int len = 0;
>
> text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
> @@ -1362,16 +1381,15 @@ static int syslog_print(char __user *buf, int size)
> size_t skip;
>
> logbuf_lock_irq();
> - if (syslog_seq < log_first_seq) {
> - /* messages are gone, move to first one */
> - syslog_seq = log_first_seq;
> - syslog_idx = log_first_idx;
> - syslog_partial = 0;
> - }
> - if (syslog_seq == log_next_seq) {
> + if (!prb_read_valid(prb, syslog_seq, &syslog_record)) {
> logbuf_unlock_irq();
> break;
> }
> + if (syslog_record.info->seq != syslog_seq) {
> + /* messages are gone, move to first one */
> + syslog_seq = syslog_record.info->seq;
> + syslog_partial = 0;
> + }
>
> /*
> * To keep reading/counting partial line consistent,
> @@ -1381,13 +1399,11 @@ static int syslog_print(char __user *buf, int size)
> syslog_time = printk_time;
>
> skip = syslog_partial;
> - msg = log_from_idx(syslog_idx);
> - n = msg_print_text(msg, true, syslog_time, text,
> - LOG_LINE_MAX + PREFIX_MAX);
> + n = record_print_text(&syslog_record, true, syslog_time, text,
> + LOG_LINE_MAX + PREFIX_MAX);
> if (n - syslog_partial <= size) {
> /* message fits into buffer, move forward */
> - syslog_idx = log_next(syslog_idx);
> - syslog_seq++;
> + syslog_seq = syslog_record.info->seq + 1;
> n -= syslog_partial;
> syslog_partial = 0;
> } else if (!len){
> @@ -1420,9 +1436,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
> {
> char *text;
> int len = 0;
> - u64 next_seq;
> u64 seq;
> - u32 idx;
> bool time;
>
> text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
> @@ -1435,38 +1449,30 @@ 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.
> */
> - seq = clear_seq;
> - idx = clear_idx;
> - while (seq < log_next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> -
> - len += msg_print_text(msg, true, time, NULL, 0);
> - idx = log_next(idx);
> - seq++;
> - }
> + prb_for_each_record(clear_seq, prb, seq, &syslog_record)
> + len += record_print_text(&syslog_record, true, time, NULL, 0);
>
> /* move first record forward until length fits into the buffer */
> - seq = clear_seq;
> - idx = clear_idx;
> - while (len > size && seq < log_next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> -
> - len -= msg_print_text(msg, true, time, NULL, 0);
> - idx = log_next(idx);
> - seq++;
> + prb_for_each_record(clear_seq, prb, seq, &syslog_record) {
> + if (len <= size)
> + break;
> + len -= record_print_text(&syslog_record, true, time, NULL, 0);
> }
>
> - /* last message fitting into this dump */
> - next_seq = log_next_seq;
> -
> len = 0;
> - while (len >= 0 && seq < next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> - int textlen = msg_print_text(msg, true, time, text,
> - LOG_LINE_MAX + PREFIX_MAX);
> + prb_for_each_record(seq, prb, seq, &syslog_record) {
> + int textlen;
>
> - idx = log_next(idx);
> - seq++;
> + if (len < 0)
> + break;
> +
> + textlen = record_print_text(&syslog_record, true, time, text,
> + LOG_LINE_MAX + PREFIX_MAX);
> +
> + if (len + textlen > size) {
> + seq--;
> + break;
> + }
>
> logbuf_unlock_irq();
> if (copy_to_user(buf + len, text, textlen))
> @@ -1474,18 +1480,10 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
> else
> len += textlen;
> logbuf_lock_irq();
> -
> - if (seq < log_first_seq) {
> - /* messages are gone, move to next one */
> - seq = log_first_seq;
> - idx = log_first_idx;
> - }
> }
>
> - if (clear) {
> - clear_seq = log_next_seq;
> - clear_idx = log_next_idx;
> - }
> + if (clear)
> + clear_seq = seq;
> logbuf_unlock_irq();
>
> 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 = log_next_seq;
> - clear_idx = log_next_idx;
> + clear_seq = prb_next_seq(prb);
> logbuf_unlock_irq();
> }
>
> @@ -1523,7 +1520,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
> if (!access_ok(buf, len))
> return -EFAULT;
> error = wait_event_interruptible(log_wait,
> - syslog_seq != log_next_seq);
> + prb_read_valid(prb, syslog_seq, NULL));
> if (error)
> return error;
> error = syslog_print(buf, len);
> @@ -1572,10 +1569,9 @@ int do_syslog(int type, char __user *buf, int len, 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 = log_first_seq;
> - syslog_idx = log_first_idx;
> + syslog_seq = prb_first_seq(prb);
> syslog_partial = 0;
> }
> if (source == SYSLOG_FROM_PROC) {
> @@ -1584,20 +1580,17 @@ int do_syslog(int type, char __user *buf, int len, int source)
> * for pending data, not the size; return the count of
> * records, not the length.
> */
> - error = log_next_seq - syslog_seq;
> + error = prb_next_seq(prb) - syslog_seq;
> } else {
> - u64 seq = syslog_seq;
> - u32 idx = syslog_idx;
> bool time = syslog_partial ? syslog_time : printk_time;
> + u64 seq;
>
> - while (seq < log_next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> -
> - error += msg_print_text(msg, true, time, NULL,
> - 0);
> + prb_for_each_record(syslog_seq, prb, seq,
> + &syslog_record) {
> + error += record_print_text(&syslog_record,
> + true, time,
> + NULL, 0);
> time = printk_time;
> - idx = log_next(idx);
> - seq++;
> }
> error -= syslog_partial;
> }
> @@ -1958,7 +1951,6 @@ asmlinkage int vprintk_emit(int facility, int level,
> int printed_len;
> bool in_sched = false, pending_output;
> unsigned long flags;
> - u64 curr_log_seq;
>
> /* Suppress unimportant messages after panic happens */
> if (unlikely(suppress_printk))
> @@ -1974,9 +1966,9 @@ asmlinkage int vprintk_emit(int facility, int level,
>
> /* This stops the holder of console_sem just where we want him */
> logbuf_lock_irqsave(flags);
> - curr_log_seq = log_next_seq;
> + pending_output = !prb_read_valid(prb, console_seq, NULL);
> printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args);
> - pending_output = (curr_log_seq != log_next_seq);
> + pending_output &= prb_read_valid(prb, console_seq, NULL);
> logbuf_unlock_irqrestore(flags);
>
> /* 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
>
> +#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 syslog,
> + 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; }
>
> #endif /* CONFIG_PRINTK */
> @@ -2406,35 +2405,28 @@ void console_unlock(void)
> }
>
> for (;;) {
> - struct printk_log *msg;
> size_t ext_len = 0;
> - size_t len;
> + size_t len = 0;
>
> 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 = sprintf(text,
> "** %llu printk messages dropped **\n",
> - log_first_seq - console_seq);
> -
> - /* messages are gone, move to first one */
> - console_seq = log_first_seq;
> - console_idx = log_first_idx;
> - } else {
> - len = 0;
> + console_record.info->seq - console_seq);
> }
> -skip:
> - if (console_seq == log_next_seq)
> - break;
> + console_seq = console_record.info->seq;
>
> - msg = 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 = log_next(console_idx);
> console_seq++;
> goto skip;
> }
> @@ -2445,19 +2437,20 @@ void console_unlock(void)
> exclusive_console = NULL;
> }
>
> - len += msg_print_text(msg,
> + len += 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 = msg_print_ext_header(ext_text,
> + ext_len = info_print_ext_header(ext_text,
> sizeof(ext_text),
> - msg, console_seq);
> + console_record.info);
> ext_len += 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 = log_next(console_idx);
> console_seq++;
> raw_spin_unlock(&logbuf_lock);
>
> @@ -2497,7 +2490,7 @@ void console_unlock(void)
> * flush, no worries.
> */
> raw_spin_lock(&logbuf_lock);
> - retry = console_seq != log_next_seq;
> + retry = prb_read_valid(prb, console_seq, NULL);
> raw_spin_unlock(&logbuf_lock);
> printk_safe_exit_irqrestore(flags);
>
> @@ -2566,8 +2559,7 @@ void console_flush_on_panic(enum con_flush_mode mode)
> unsigned long flags;
>
> logbuf_lock_irqsave(flags);
> - console_seq = log_first_seq;
> - console_idx = log_first_idx;
> + console_seq = 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 = syslog_seq;
> - console_idx = 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 = newcon;
> exclusive_console_stop_seq = console_seq;
> + console_seq = syslog_seq;
> logbuf_unlock_irqrestore(flags);
> }
> console_unlock();
> @@ -3127,9 +3118,7 @@ void kmsg_dump(enum kmsg_dump_reason reason)
>
> logbuf_lock_irqsave(flags);
> dumper->cur_seq = clear_seq;
> - dumper->cur_idx = clear_idx;
> - dumper->next_seq = log_next_seq;
> - dumper->next_idx = log_next_idx;
> + dumper->next_seq = prb_next_seq(prb);
> logbuf_unlock_irqrestore(flags);
>
> /* 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 = {
> + .info = &info,
> + .text_buf = line,
> + .text_buf_size = size,
> + };
> + unsigned int line_count;
> size_t l = 0;
> bool ret = false;
>
> if (!dumper->active)
> goto out;
>
> - if (dumper->cur_seq < log_first_seq) {
> - /* messages are gone, move to first available one */
> - dumper->cur_seq = log_first_seq;
> - dumper->cur_idx = log_first_idx;
> - }
> + /* Count text lines instead of reading text? */
> + if (!line)
> + r.text_line_count = &line_count;
>
> - /* last entry */
> - if (dumper->cur_seq >= log_next_seq)
> + if (!prb_read_valid(prb, dumper->cur_seq, &r))
> goto out;
>
> - msg = log_from_idx(dumper->cur_idx);
> - l = msg_print_text(msg, syslog, printk_time, line, size);
> + l = record_print_text_inline(&r, syslog, printk_time);
>
> - dumper->cur_idx = log_next(dumper->cur_idx);
> - dumper->cur_seq++;
> + dumper->cur_seq = r.info->seq + 1;
> ret = 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 = {
> + .info = &info,
> + .text_line_count = &line_count,
> + };
> unsigned long flags;
> u64 seq;
> - u32 idx;
> u64 next_seq;
> - u32 next_idx;
> size_t l = 0;
> bool ret = false;
> bool time = printk_time;
>
> - if (!dumper->active)
> + if (!dumper->active || !buf || !size)
> goto out;
>
> 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 = log_first_seq;
> - dumper->cur_idx = log_first_idx;
> + dumper->cur_seq = prb_first_seq(prb);
> }
>
> /* last entry */
> @@ -3272,41 +3266,43 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
>
> /* calculate length of entire buffer */
> seq = dumper->cur_seq;
> - idx = dumper->cur_idx;
> - while (seq < dumper->next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> -
> - l += msg_print_text(msg, true, time, NULL, 0);
> - idx = log_next(idx);
> - seq++;
> + while (prb_read_valid(prb, seq, &r)) {
> + if (r.info->seq >= dumper->next_seq)
> + break;
> + l += record_print_text_inline(&r, true, time);
> + seq = r.info->seq + 1;
> }
>
> /* move first record forward until length fits into the buffer */
> seq = dumper->cur_seq;
> - idx = dumper->cur_idx;
> - while (l >= size && seq < dumper->next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> -
> - l -= msg_print_text(msg, true, time, NULL, 0);
> - idx = log_next(idx);
> - seq++;
> + while (l >= size && prb_read_valid(prb, seq, &r)) {
> + if (r.info->seq >= dumper->next_seq)
> + break;
> + l -= record_print_text_inline(&r, true, time);
> + seq = r.info->seq + 1;
> }
>
> /* last message in next interation */
> next_seq = seq;
> - next_idx = idx;
> +
> + /* actually read data into the buffer now */
> + r.text_buf = buf;
> + r.text_buf_size = size;
> + r.text_line_count = NULL;
>
> l = 0;
> - while (seq < dumper->next_seq) {
> - struct printk_log *msg = log_from_idx(idx);
> + while (prb_read_valid(prb, seq, &r)) {
> + if (r.info->seq >= dumper->next_seq)
> + break;
> +
> + l += record_print_text_inline(&r, syslog, time);
> + r.text_buf = buf + l;
> + r.text_buf_size = size - l;
>
> - l += msg_print_text(msg, syslog, time, buf + l, size - l);
> - idx = log_next(idx);
> - seq++;
> + seq = r.info->seq + 1;
> }
>
> dumper->next_seq = next_seq;
> - dumper->next_idx = next_idx;
> ret = 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 = clear_seq;
> - dumper->cur_idx = clear_idx;
> - dumper->next_seq = log_next_seq;
> - dumper->next_idx = log_next_idx;
> + dumper->next_seq = prb_next_seq(prb);
> }
>
> /**
>

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