Am 27.09.2012 18:04, schrieb Jan H. Schönherr:
> Am 27.09.2012 17:46, schrieb Jan H. Schönherr:
>> If we say "if LOG_CONT is set, this message continues the previous one",
>> we can also say "there is no prefix on this message". Then on the other
>> hand, we would need a "whatever comes next, it does not continue this
>> message"....
>
> Thinking a bit longer about this one.
>
> If really, really everything passes through vprintk_emit()
> then we could keep all info about the previous message
> there and definitely decide whether the current message continues
> the previous one.
>
> Then, we wouldn't need to track the previous flags everywhere.
Here is a patch that does just that.
Seems to work. And it makes the code easier to understand.
A more detailed description is below.
Here is, what it now looks like:
virtual-parasit ~ # insmod foo.ko; rmmod foo
[ 29.894348] newline 1
[ 29.894686] newline 2
[ 29.895067] newline 3
[ 29.895469] newline 4
[ 29.895859] newline 5
[ 29.895860] newline 6
[ 29.895860] newline 7
[ 29.895860] newline 8
[ 29.895861] newline 9
[ 29.895861] newline 10 continued 1 continued 2 continued 3
[ 29.895862] newline 11 continued 4 continued 5 continued 6 continued 7
[ 29.895863] newline 12
[ 29.895864] newline 13
[ 29.895864] newline 15
[ 29.895864] newline 16a
[ 29.895864] newline 16b
[ 29.895864] newline 16c continued 8
[ 29.895864] newline 17
[ 29.895865] newline 18a
newline 18b
newline 18c continued 9virtual-parasit ~ # insmod foo.ko; rmmod foo
[ 32.291223] newline 1
[ 32.291529] newline 2
[ 32.291847] newline 3
[ 32.291848] newline 4
[ 32.291848] newline 5
[ 32.291848] newline 6
[ 32.291849] newline 7
[ 32.291849] newline 8
[ 32.291849] newline 9
[ 32.291850] newline 10 continued 1 continued 2 continued 3
[ 32.291851] newline 11 continued 4 continued 5 continued 6 continued 7
[ 32.291853] newline 12
[ 32.291858] newline 13
[ 32.291859] newline 15
[ 32.291859] newline 16a
[ 32.291859] newline 16b
[ 32.291859] newline 16c continued 8
[ 32.291860] newline 17
[ 32.291860] newline 18a
[ 32.291860] newline 18b
[ 32.291860] newline 18c continued 9virtual-parasit ~ # cat /dev/kmsg
<snip>
7,397,29894348,-;newline 1
7,398,29894686,c;newline 2
7,399,29895067,-;newline 3
7,400,29895469,c;newline 4
7,401,29895859,-;newline 5
7,402,29895860,-;newline 6
6,403,29895860,-;newline 7
7,404,29895860,-;newline 8
6,405,29895861,-;newline 9
7,406,29895861,-;newline 10 continued 1 continued 2 continued 3
7,407,29895862,-;newline 11 continued 4 continued 5 continued 6 continued 7
6,408,29895863,-;newline 12
4,409,29895864,-;newline 13
4,410,29895864,-;newline 15
7,411,29895864,-;newline 16a\x0anewline 16b\x0anewline 16c continued
8\x0anewline 17
7,412,29895865,-;newline 18a\x0anewline 18b\x0anewline 18c continued 9
7,413,32291223,c;newline 1
7,414,32291529,-;newline 2
7,415,32291847,c;newline 3
7,416,32291848,c;newline 4
7,417,32291848,c;newline 5
7,418,32291848,c;newline 6
6,419,32291849,c;newline 7
7,420,32291849,c;newline 8
6,421,32291849,c;newline 9
7,422,32291850,c;newline 10
7,423,32291850,+; continued 1
7,424,32291851,+; continued 2
7,425,32291851,+; continued 3
7,426,32291851,c;newline 11
7,427,32291852,+; continued 4
7,428,32291852,+; continued 5
7,429,32291853,+; continued 6
7,430,32291853,+; continued 7
6,431,32291853,-;newline 12
4,432,32291858,-;newline 13
4,433,32291859,-;newline 15
7,434,32291859,c;newline 16a\x0anewline 16b\x0anewline 16c
7,435,32291860,+; continued 8\x0anewline 17
7,436,32291860,c;newline 18a\x0anewline 18b\x0anewline 18c
7,437,32291861,+; continued 9
What do you think?
Regards
Jan
---- 8< ----
From: Jan H. Schönherr <schn...@cs.tu-berlin.de>
Subject: printk: rework continuation record handling
Centrally track the previous record in vprintk_emit() itself instead of
doing it from formatting code. This enables us to setup the flags of the
current record, so that a later formatting is possible without knowledge
of the previous record.
This simplifies the code and also fixes an issue of too aggressive merging
of printk()s that have a prefix but no newline at the end by defining
the flags more clearly.
The flags have now the following meaning if set:
LOG_CONT: This record continues the previous record.
LOG_NEWLINE: This record finishes the current message, i. e., ends
with a newline.
LOG_PREFIX: The previous record should have had LOG_NEWLINE set,
but it was unknown at that time, i. e., this record
starts with a newline.
Signed-off-by: Jan H. Schönherr <schn...@cs.tu-berlin.de>
---
kernel/printk.c | 243 ++++++++++++++++++++++++++++----------------------------
1 Datei geändert, 120 Zeilen hinzugefügt(+), 123 Zeilen entfernt(-)
diff --git a/kernel/printk.c b/kernel/printk.c
index 66a2ea3..6bea6e7 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -195,9 +195,9 @@ static int console_may_schedule;
enum log_flags {
LOG_NOCONS = 1, /* already flushed, do not print to console */
- LOG_NEWLINE = 2, /* text ended with a newline */
- LOG_PREFIX = 4, /* text started with a prefix */
- LOG_CONT = 8, /* text is a fragment of a continuation line */
+ LOG_NEWLINE = 2, /* end fragment with a newline */
+ LOG_PREFIX = 4, /* start fragment with a newline */
+ LOG_CONT = 8, /* fragment continues previous fragmet */
};
struct log {
@@ -220,7 +220,6 @@ static DEFINE_RAW_SPINLOCK(logbuf_lock);
/* the next printk record to read by syslog(READ) or /proc/kmsg */
static u64 syslog_seq;
static u32 syslog_idx;
-static enum log_flags syslog_prev;
static size_t syslog_partial;
/* index and sequence number of the first record stored in the buffer */
@@ -234,7 +233,6 @@ static u32 log_next_idx;
/* the next printk record to write to the console */
static u64 console_seq;
static u32 console_idx;
-static enum log_flags console_prev;
/* the next printk record to read after the last 'clear' command */
static u64 clear_seq;
@@ -366,7 +364,6 @@ static void log_store(int facility, int level,
struct devkmsg_user {
u64 seq;
u32 idx;
- enum log_flags prev;
struct mutex lock;
char buf[8192];
};
@@ -481,16 +478,14 @@ static ssize_t devkmsg_read(struct file *file, char
__user *buf,
* better readable output. 'c' in the record flags mark the first
* fragment of a line, '+' the following.
*/
- if (msg->flags & LOG_CONT && !(user->prev & LOG_CONT))
- cont = 'c';
- else if ((msg->flags & LOG_CONT) ||
- ((user->prev & LOG_CONT) && !(msg->flags & LOG_PREFIX)))
+ if (msg->flags & LOG_CONT)
cont = '+';
+ else if (!(msg->flags & LOG_NEWLINE))
+ cont = 'c';
len = sprintf(user->buf, "%u,%llu,%llu,%c;",
(msg->facility << 3) | msg->level,
user->seq, ts_usec, cont);
- user->prev = msg->flags;
/* escape non-printable characters */
for (i = 0; i < msg->text_len; i++) {
@@ -878,24 +873,19 @@ static size_t print_prefix(const struct log *msg, bool
syslog, char *buf)
return len;
}
-static size_t msg_print_text(const struct log *msg, enum log_flags prev,
+static size_t msg_print_text(const struct log *msg,
bool syslog, char *buf, size_t size)
{
const char *text = log_text(msg);
size_t text_size = msg->text_len;
- bool prefix = true;
- bool newline = true;
+ bool prefix = !(msg->flags & LOG_CONT);
+ bool newline = msg->flags & LOG_NEWLINE;
size_t len = 0;
- if ((prev & LOG_CONT) && !(msg->flags & LOG_PREFIX))
- prefix = false;
-
- if (msg->flags & LOG_CONT) {
- if ((prev & LOG_CONT) && !(prev & LOG_NEWLINE))
- prefix = false;
-
- if (!(msg->flags & LOG_NEWLINE))
- newline = false;
+ if (msg->flags & LOG_PREFIX) {
+ if (buf)
+ buf[len] = '\n';
+ len++;
}
do {
@@ -956,7 +946,6 @@ static int syslog_print(char __user *buf, int size)
/* messages are gone, move to first one */
syslog_seq = log_first_seq;
syslog_idx = log_first_idx;
- syslog_prev = 0;
syslog_partial = 0;
}
if (syslog_seq == log_next_seq) {
@@ -966,13 +955,12 @@ static int syslog_print(char __user *buf, int size)
skip = syslog_partial;
msg = log_from_idx(syslog_idx);
- n = msg_print_text(msg, syslog_prev, true, text,
+ n = msg_print_text(msg, true, 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_prev = msg->flags;
n -= syslog_partial;
syslog_partial = 0;
} else if (!len){
@@ -1015,7 +1003,6 @@ static int syslog_print_all(char __user *buf, int size,
bool clear)
u64 next_seq;
u64 seq;
u32 idx;
- enum log_flags prev;
if (clear_seq < log_first_seq) {
/* messages are gone, move to first available one */
@@ -1029,12 +1016,10 @@ static int syslog_print_all(char __user *buf, int size,
bool clear)
*/
seq = clear_seq;
idx = clear_idx;
- prev = 0;
while (seq < log_next_seq) {
struct log *msg = log_from_idx(idx);
- len += msg_print_text(msg, prev, true, NULL, 0);
- prev = msg->flags;
+ len += msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
}
@@ -1042,12 +1027,10 @@ static int syslog_print_all(char __user *buf, int size,
bool clear)
/* move first record forward until length fits into the buffer
*/
seq = clear_seq;
idx = clear_idx;
- prev = 0;
while (len > size && seq < log_next_seq) {
struct log *msg = log_from_idx(idx);
- len -= msg_print_text(msg, prev, true, NULL, 0);
- prev = msg->flags;
+ len -= msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
}
@@ -1056,12 +1039,11 @@ static int syslog_print_all(char __user *buf, int size,
bool clear)
next_seq = log_next_seq;
len = 0;
- prev = 0;
while (len >= 0 && seq < next_seq) {
struct log *msg = log_from_idx(idx);
int textlen;
- textlen = msg_print_text(msg, prev, true, text,
+ textlen = msg_print_text(msg, true, text,
LOG_LINE_MAX + PREFIX_MAX);
if (textlen < 0) {
len = textlen;
@@ -1069,7 +1051,6 @@ static int syslog_print_all(char __user *buf, int size,
bool clear)
}
idx = log_next(idx);
seq++;
- prev = msg->flags;
raw_spin_unlock_irq(&logbuf_lock);
if (copy_to_user(buf + len, text, textlen))
@@ -1082,7 +1063,6 @@ static int syslog_print_all(char __user *buf, int size,
bool clear)
/* messages are gone, move to next one */
seq = log_first_seq;
idx = log_first_idx;
- prev = 0;
}
}
}
@@ -1187,7 +1167,6 @@ int do_syslog(int type, char __user *buf, int len, bool
from_file)
/* messages are gone, move to first one */
syslog_seq = log_first_seq;
syslog_idx = log_first_idx;
- syslog_prev = 0;
syslog_partial = 0;
}
if (from_file) {
@@ -1200,16 +1179,14 @@ int do_syslog(int type, char __user *buf, int len, bool
from_file)
} else {
u64 seq = syslog_seq;
u32 idx = syslog_idx;
- enum log_flags prev = syslog_prev;
error = 0;
while (seq < log_next_seq) {
struct log *msg = log_from_idx(idx);
- error += msg_print_text(msg, prev, true, NULL,
0);
+ error += msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
- prev = msg->flags;
}
error -= syslog_partial;
}
@@ -1391,9 +1368,10 @@ static struct cont {
u8 facility; /* log level of first message */
enum log_flags flags; /* prefix, newline flags */
bool flushed:1; /* buffer sealed and committed */
-} cont;
+ const char *dict; u16 dict_len;
+} cont = { .flags = LOG_NEWLINE, };
-static void cont_flush(enum log_flags flags)
+static void cont_flush(void)
{
if (cont.flushed)
return;
@@ -1403,52 +1381,110 @@ static void cont_flush(enum log_flags flags)
if (cont.cons) {
/*
* If a fragment of this line was directly flushed to the
- * console; wait for the console to pick up the rest of the
+ * console, wait for the console to pick up the rest of the
* line. LOG_NOCONS suppresses a duplicated output.
*/
- log_store(cont.facility, cont.level, flags | LOG_NOCONS,
+ log_store(cont.facility, cont.level, cont.flags | LOG_NOCONS,
cont.ts_nsec, NULL, 0, cont.buf, cont.len);
- cont.flags = flags;
+ if (cont.flags & LOG_NEWLINE)
+ cont.buf[cont.len++] = '\n';
cont.flushed = true;
} else {
/*
* If no fragment of this line ever reached the console,
* just submit it to the store and free the buffer.
*/
- log_store(cont.facility, cont.level, flags, 0,
+ log_store(cont.facility, cont.level, cont.flags, cont.ts_nsec,
NULL, 0, cont.buf, cont.len);
cont.len = 0;
}
}
-static bool cont_add(int facility, int level, const char *text, size_t len)
+static void cont_add(int facility, int level, enum log_flags flags,
+ const char *dict, u16 dict_len,
+ const char *text, size_t text_len)
{
- if (cont.len && cont.flushed)
- return false;
+ /* BUG_ON(flags & ~(LOG_NEWLINE | LOG_PREFIX)); */
- if (cont.len + len > sizeof(cont.buf)) {
- /* the line gets too long, split it up in separate records */
- cont_flush(LOG_CONT);
- return false;
+ if (cont.len && !cont.flushed) {
+ /*
+ * previous fragment still buffered, let's have a look
+ * at it
+ */
+ /* BUG_ON(cont.flags & LOG_NEWLINE); */
+
+ if (cont.owner != current || cont.facility != facility ||
+ flags & LOG_PREFIX) {
+ /*
+ * current fragment does not continue previous
+ * fragment
+ */
+ cont.flags |= LOG_NEWLINE;
+ cont_flush();
+ } else if (cont.len + text_len + 1 > sizeof(cont.buf)) {
+ /*
+ * current fragment continues previous fragment,
+ * but we cannot merge them as the result would be
+ * too long
+ */
+ flags |= LOG_CONT;
+ cont_flush();
+ } else {
+ /*
+ * current fragment continues previous fragment
+ * and we are able to merge them
+ */
+ memcpy(cont.buf + cont.len, text, text_len);
+ cont.len += text_len;
+ cont.flags |= flags;
+ if (cont.len > (sizeof(cont.buf) * 80) / 100 ||
+ cont.flags & LOG_NEWLINE)
+ cont_flush();
+ return;
+ }
}
- if (!cont.len) {
- cont.facility = facility;
- cont.level = level;
- cont.owner = current;
- cont.ts_nsec = local_clock();
- cont.flags = 0;
- cont.cons = 0;
- cont.flushed = false;
+ if (cont.owner == current && cont.facility == facility &&
+ !(cont.flags & LOG_NEWLINE) && !(flags & LOG_PREFIX)) {
+ /* current fragment continues previous fragment */
+ flags |= LOG_CONT;
+ level = cont.level;
}
- memcpy(cont.buf + cont.len, text, len);
- cont.len += len;
+ flags &= ~LOG_PREFIX;
+ if (!(cont.flags & LOG_NEWLINE) && !(flags & LOG_CONT)) {
+ /* previous fragment missed a newline */
+ flags |= LOG_PREFIX;
+ }
- if (cont.len > (sizeof(cont.buf) * 80) / 100)
- cont_flush(LOG_CONT);
+ cont.flags = flags;
+ cont.owner = current;
+ cont.facility = facility;
+ cont.level = level;
- return true;
+ if ((cont.len && cont.flushed) || (flags & LOG_NEWLINE) ||
+ (text_len > (sizeof(cont.buf) * 80) / 100)) {
+ /*
+ * cont.buf + cont.cons + cont.len still occupied
+ * OR current fragment is self-contained
+ * OR current fragment is too long
+ *
+ * store fragment directly
+ */
+ log_store(facility, level, flags, 0,
+ dict, dict_len, text, text_len);
+ return;
+ }
+
+ /* BUG_ON(cont.len); */
+ /* BUG_ON(flags & LOG_NEWLINE); */
+
+ /* buffer is empty, buffer current fragment */
+ memcpy(cont.buf, text, text_len);
+ cont.len = text_len;
+ cont.ts_nsec = local_clock();
+ cont.cons = 0;
+ cont.flushed = false;
}
static size_t cont_print_text(char *text, size_t size)
@@ -1456,8 +1492,10 @@ static size_t cont_print_text(char *text, size_t size)
size_t textlen = 0;
size_t len;
- if (cont.cons == 0 && (console_prev & LOG_NEWLINE)) {
- textlen += print_time(cont.ts_nsec, text);
+ if (cont.cons == 0 && !(cont.flags & LOG_CONT)) {
+ if (cont.flags & LOG_PREFIX)
+ text[textlen++] = '\n';
+ textlen += print_time(cont.ts_nsec, text + textlen);
size -= textlen;
}
@@ -1471,8 +1509,6 @@ static size_t cont_print_text(char *text, size_t size)
}
if (cont.flushed) {
- if (cont.flags & LOG_NEWLINE)
- text[textlen++] = '\n';
/* got everything, release buffer */
cont.len = 0;
}
@@ -1528,7 +1564,7 @@ asmlinkage int vprintk_emit(int facility, int level,
recursion_bug = 0;
printed_len += strlen(recursion_msg);
/* emit KERN_CRIT message */
- log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+ cont_add(0, 2, LOG_PREFIX | LOG_NEWLINE,
NULL, 0, recursion_msg, printed_len);
}
@@ -1555,7 +1591,8 @@ asmlinkage int vprintk_emit(int facility, int level,
if (level == -1)
level = kern_level - '0';
case 'd': /* KERN_DEFAULT */
- lflags |= LOG_PREFIX;
+ if (level == -1)
+ level = default_message_loglevel;
case 'c': /* KERN_CONT */
break;
}
@@ -1566,41 +1603,14 @@ asmlinkage int vprintk_emit(int facility, int level,
if (level == -1)
level = default_message_loglevel;
+ else
+ lflags |= LOG_PREFIX;
if (dict)
- lflags |= LOG_PREFIX|LOG_NEWLINE;
+ lflags |= LOG_PREFIX | LOG_NEWLINE;
- if (!(lflags & LOG_NEWLINE)) {
- /*
- * Flush the conflicting buffer. An earlier newline was missing,
- * or another task also prints continuation lines.
- */
- if (cont.len && (lflags & LOG_PREFIX || cont.owner != current))
- cont_flush(LOG_NEWLINE);
+ cont_add(facility, level, lflags, dict, dictlen, text, text_len);
- /* buffer line if possible, otherwise store it right away */
- if (!cont_add(facility, level, text, text_len))
- log_store(facility, level, lflags | LOG_CONT, 0,
- dict, dictlen, text, text_len);
- } else {
- bool stored = false;
-
- /*
- * If an earlier newline was missing and it was the same task,
- * either merge it with the current buffer and flush, or if
- * there was a race with interrupts (prefix == true) then just
- * flush it out and store this line separately.
- */
- if (cont.len && cont.owner == current) {
- if (!(lflags & LOG_PREFIX))
- stored = cont_add(facility, level, text,
text_len);
- cont_flush(LOG_NEWLINE);
- }
-
- if (!stored)
- log_store(facility, level, lflags, 0,
- dict, dictlen, text, text_len);
- }
printed_len += text_len;
/*
@@ -1694,11 +1704,9 @@ static u64 syslog_seq;
static u32 syslog_idx;
static u64 console_seq;
static u32 console_idx;
-static enum log_flags syslog_prev;
static u64 log_first_seq;
static u32 log_first_idx;
static u64 log_next_seq;
-static enum log_flags console_prev;
static struct cont {
size_t len;
size_t cons;
@@ -1708,7 +1716,7 @@ static struct cont {
static struct log *log_from_idx(u32 idx) { return NULL; }
static u32 log_next(u32 idx) { return 0; }
static void call_console_drivers(int level, const char *text, size_t len) {}
-static size_t msg_print_text(const struct log *msg, enum log_flags prev,
+static size_t msg_print_text(const struct log *msg,
bool syslog, char *buf, size_t size) { return 0; }
static size_t cont_print_text(char *text, size_t size) { return 0; }
@@ -2058,7 +2066,6 @@ again:
/* messages are gone, move to first one */
console_seq = log_first_seq;
console_idx = log_first_idx;
- console_prev = 0;
}
skip:
if (console_seq == log_next_seq)
@@ -2078,16 +2085,14 @@ skip:
* will properly dump everything later.
*/
msg->flags &= ~LOG_NOCONS;
- console_prev = msg->flags;
goto skip;
}
level = msg->level;
- len = msg_print_text(msg, console_prev, false,
+ len = msg_print_text(msg, false,
text, sizeof(text));
console_idx = log_next(console_idx);
console_seq++;
- console_prev = msg->flags;
raw_spin_unlock(&logbuf_lock);
stop_critical_timings(); /* don't trace print latency */
@@ -2350,7 +2355,6 @@ void register_console(struct console *newcon)
raw_spin_lock_irqsave(&logbuf_lock, flags);
console_seq = syslog_seq;
console_idx = syslog_idx;
- console_prev = syslog_prev;
raw_spin_unlock_irqrestore(&logbuf_lock, flags);
/*
* We're about to replay the log buffer. Only do this to the
@@ -2642,7 +2646,7 @@ bool kmsg_dump_get_line_nolock(struct kmsg_dumper
*dumper, bool syslog,
goto out;
msg = log_from_idx(dumper->cur_idx);
- l = msg_print_text(msg, 0, syslog, line, size);
+ l = msg_print_text(msg, syslog, line, size);
dumper->cur_idx = log_next(dumper->cur_idx);
dumper->cur_seq++;
@@ -2711,7 +2715,6 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper,
bool syslog,
u32 idx;
u64 next_seq;
u32 next_idx;
- enum log_flags prev;
size_t l = 0;
bool ret = false;
@@ -2734,27 +2737,23 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper,
bool syslog,
/* calculate length of entire buffer */
seq = dumper->cur_seq;
idx = dumper->cur_idx;
- prev = 0;
while (seq < dumper->next_seq) {
struct log *msg = log_from_idx(idx);
- l += msg_print_text(msg, prev, true, NULL, 0);
+ l += msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
- prev = msg->flags;
}
/* move first record forward until length fits into the buffer */
seq = dumper->cur_seq;
idx = dumper->cur_idx;
- prev = 0;
while (l > size && seq < dumper->next_seq) {
struct log *msg = log_from_idx(idx);
- l -= msg_print_text(msg, prev, true, NULL, 0);
+ l -= msg_print_text(msg, true, NULL, 0);
idx = log_next(idx);
seq++;
- prev = msg->flags;
}
/* last message in next interation */
@@ -2762,14 +2761,12 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper,
bool syslog,
next_idx = idx;
l = 0;
- prev = 0;
while (seq < dumper->next_seq) {
struct log *msg = log_from_idx(idx);
- l += msg_print_text(msg, prev, syslog, buf + l, size - l);
+ l += msg_print_text(msg, syslog, buf + l, size - l);
idx = log_next(idx);
seq++;
- prev = msg->flags;
}
dumper->next_seq = next_seq;
--
1.7.12
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