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authorLinus Torvalds <torvalds@linux-foundation.org>2018-12-27 11:24:43 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2018-12-27 11:24:43 -0800
commita3b5c1065f3fb934a87dd07d23def99916023d6f (patch)
treeec349329c1ec47bb9e7d7cc548fb20510d43150d /kernel/printk/printk.c
parentc6f1b355d451680a45d63ce66cea67057c938a87 (diff)
parent07c17732bd687567802aaa5fa5c101c2776565d1 (diff)
Merge tag 'printk-for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk
Pull printk updates from Petr Mladek: - Keep spinlocks busted until the end of panic() - Fix races between calculating number of messages that would fit into user space buffers, filling the buffers, and switching printk.time parameter - Some code clean up * tag 'printk-for-4.21' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk: printk: Remove print_prefix() calls with NULL buffer. printk: fix printk_time race. printk: Make printk_emit() local function. panic: avoid deadlocks in re-entrant console drivers
Diffstat (limited to 'kernel/printk/printk.c')
-rw-r--r--kernel/printk/printk.c131
1 files changed, 63 insertions, 68 deletions
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 1b2a029360b7..1306fe0c1dc6 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -403,6 +403,7 @@ DECLARE_WAIT_QUEUE_HEAD(log_wait);
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;
@@ -752,6 +753,19 @@ struct devkmsg_user {
char buf[CONSOLE_EXT_LOG_MAX];
};
+static __printf(3, 4) __cold
+int devkmsg_emit(int facility, int level, const char *fmt, ...)
+{
+ va_list args;
+ int r;
+
+ va_start(args, fmt);
+ r = vprintk_emit(facility, level, NULL, 0, fmt, args);
+ va_end(args);
+
+ return r;
+}
+
static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
{
char *buf, *line;
@@ -810,7 +824,7 @@ static ssize_t devkmsg_write(struct kiocb *iocb, struct iov_iter *from)
}
}
- printk_emit(facility, level, NULL, 0, "%s", line);
+ devkmsg_emit(facility, level, "%s", line);
kfree(buf);
return ret;
}
@@ -1213,50 +1227,39 @@ static inline void boot_delay_msec(int level)
static bool printk_time = IS_ENABLED(CONFIG_PRINTK_TIME);
module_param_named(time, printk_time, bool, S_IRUGO | S_IWUSR);
-static size_t print_time(u64 ts, char *buf)
+static size_t print_syslog(unsigned int level, char *buf)
{
- unsigned long rem_nsec;
-
- if (!printk_time)
- return 0;
-
- rem_nsec = do_div(ts, 1000000000);
+ return sprintf(buf, "<%u>", level);
+}
- if (!buf)
- return snprintf(NULL, 0, "[%5lu.000000] ", (unsigned long)ts);
+static size_t print_time(u64 ts, char *buf)
+{
+ unsigned long rem_nsec = do_div(ts, 1000000000);
return sprintf(buf, "[%5lu.%06lu] ",
(unsigned long)ts, rem_nsec / 1000);
}
-static size_t print_prefix(const struct printk_log *msg, bool syslog, char *buf)
+static size_t print_prefix(const struct printk_log *msg, bool syslog,
+ bool time, char *buf)
{
size_t len = 0;
- unsigned int prefix = (msg->facility << 3) | msg->level;
-
- if (syslog) {
- if (buf) {
- len += sprintf(buf, "<%u>", prefix);
- } else {
- len += 3;
- if (prefix > 999)
- len += 3;
- else if (prefix > 99)
- len += 2;
- else if (prefix > 9)
- len++;
- }
- }
- len += print_time(msg->ts_nsec, buf ? buf + len : NULL);
+ if (syslog)
+ len = print_syslog((msg->facility << 3) | msg->level, buf);
+ if (time)
+ len += print_time(msg->ts_nsec, buf + len);
return len;
}
-static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *buf, size_t size)
+static size_t msg_print_text(const struct printk_log *msg, bool syslog,
+ bool time, char *buf, size_t size)
{
const char *text = log_text(msg);
size_t text_size = msg->text_len;
size_t len = 0;
+ char prefix[PREFIX_MAX];
+ const size_t prefix_len = print_prefix(msg, syslog, time, prefix);
do {
const char *next = memchr(text, '\n', text_size);
@@ -1271,19 +1274,17 @@ static size_t msg_print_text(const struct printk_log *msg, bool syslog, char *bu
}
if (buf) {
- if (print_prefix(msg, syslog, NULL) +
- text_len + 1 >= size - len)
+ if (prefix_len + text_len + 1 >= size - len)
break;
- len += print_prefix(msg, syslog, buf + len);
+ memcpy(buf + len, prefix, prefix_len);
+ len += prefix_len;
memcpy(buf + len, text, text_len);
len += text_len;
buf[len++] = '\n';
} else {
/* SYSLOG_ACTION_* buffer size only calculation */
- len += print_prefix(msg, syslog, NULL);
- len += text_len;
- len++;
+ len += prefix_len + text_len + 1;
}
text = next;
@@ -1318,9 +1319,17 @@ static int syslog_print(char __user *buf, int size)
break;
}
+ /*
+ * To keep reading/counting partial line consistent,
+ * use printk_time value as of the beginning of a line.
+ */
+ if (!syslog_partial)
+ syslog_time = printk_time;
+
skip = syslog_partial;
msg = log_from_idx(syslog_idx);
- n = msg_print_text(msg, true, text, LOG_LINE_MAX + PREFIX_MAX);
+ n = msg_print_text(msg, 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);
@@ -1360,11 +1369,13 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
u64 next_seq;
u64 seq;
u32 idx;
+ bool time;
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
+ time = printk_time;
logbuf_lock_irq();
/*
* Find first record that fits, including all following records,
@@ -1375,7 +1386,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
while (seq < log_next_seq) {
struct printk_log *msg = log_from_idx(idx);
- len += msg_print_text(msg, true, NULL, 0);
+ len += msg_print_text(msg, true, time, NULL, 0);
idx = log_next(idx);
seq++;
}
@@ -1386,7 +1397,7 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
while (len > size && seq < log_next_seq) {
struct printk_log *msg = log_from_idx(idx);
- len -= msg_print_text(msg, true, NULL, 0);
+ len -= msg_print_text(msg, true, time, NULL, 0);
idx = log_next(idx);
seq++;
}
@@ -1397,14 +1408,9 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
len = 0;
while (len >= 0 && seq < next_seq) {
struct printk_log *msg = log_from_idx(idx);
- int textlen;
+ int textlen = msg_print_text(msg, true, time, text,
+ LOG_LINE_MAX + PREFIX_MAX);
- textlen = msg_print_text(msg, true, text,
- LOG_LINE_MAX + PREFIX_MAX);
- if (textlen < 0) {
- len = textlen;
- break;
- }
idx = log_next(idx);
seq++;
@@ -1528,11 +1534,14 @@ int do_syslog(int type, char __user *buf, int len, int source)
} else {
u64 seq = syslog_seq;
u32 idx = syslog_idx;
+ bool time = syslog_partial ? syslog_time : printk_time;
while (seq < log_next_seq) {
struct printk_log *msg = log_from_idx(idx);
- error += msg_print_text(msg, true, NULL, 0);
+ error += msg_print_text(msg, true, time, NULL,
+ 0);
+ time = printk_time;
idx = log_next(idx);
seq++;
}
@@ -1935,21 +1944,6 @@ asmlinkage int vprintk(const char *fmt, va_list args)
}
EXPORT_SYMBOL(vprintk);
-asmlinkage int printk_emit(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, ...)
-{
- va_list args;
- int r;
-
- va_start(args, fmt);
- r = vprintk_emit(facility, level, dict, dictlen, fmt, args);
- va_end(args);
-
- return r;
-}
-EXPORT_SYMBOL(printk_emit);
-
int vprintk_default(const char *fmt, va_list args)
{
int r;
@@ -2005,6 +1999,7 @@ EXPORT_SYMBOL(printk);
#define LOG_LINE_MAX 0
#define PREFIX_MAX 0
+#define printk_time false
static u64 syslog_seq;
static u32 syslog_idx;
@@ -2028,8 +2023,8 @@ 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, char *buf, size_t size) { return 0; }
+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 */
@@ -2387,8 +2382,7 @@ skip:
len += msg_print_text(msg,
console_msg_format & MSG_FORMAT_SYSLOG,
- text + len,
- sizeof(text) - len);
+ printk_time, text + len, sizeof(text) - len);
if (nr_ext_console_drivers) {
ext_len = msg_print_ext_header(ext_text,
sizeof(ext_text),
@@ -3112,7 +3106,7 @@ 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, syslog, line, size);
+ l = msg_print_text(msg, syslog, printk_time, line, size);
dumper->cur_idx = log_next(dumper->cur_idx);
dumper->cur_seq++;
@@ -3183,6 +3177,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
u32 next_idx;
size_t l = 0;
bool ret = false;
+ bool time = printk_time;
if (!dumper->active)
goto out;
@@ -3206,7 +3201,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
while (seq < dumper->next_seq) {
struct printk_log *msg = log_from_idx(idx);
- l += msg_print_text(msg, true, NULL, 0);
+ l += msg_print_text(msg, true, time, NULL, 0);
idx = log_next(idx);
seq++;
}
@@ -3217,7 +3212,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
while (l > size && seq < dumper->next_seq) {
struct printk_log *msg = log_from_idx(idx);
- l -= msg_print_text(msg, true, NULL, 0);
+ l -= msg_print_text(msg, true, time, NULL, 0);
idx = log_next(idx);
seq++;
}
@@ -3230,7 +3225,7 @@ bool kmsg_dump_get_buffer(struct kmsg_dumper *dumper, bool syslog,
while (seq < dumper->next_seq) {
struct printk_log *msg = log_from_idx(idx);
- l += msg_print_text(msg, syslog, buf + l, size - l);
+ l += msg_print_text(msg, syslog, time, buf + l, size - l);
idx = log_next(idx);
seq++;
}