{
return srcu_read_lock_held(&console_srcu);
}
+EXPORT_SYMBOL(console_srcu_read_lock_is_held);
#endif
enum devkmsg_log_bits {
.val[1] = 0,
};
- #ifdef CONFIG_PRINTK_CALLER
- #define PREFIX_MAX 48
- #else
- #define PREFIX_MAX 32
- #endif
-
- /* the maximum size of a formatted record (i.e. with prefix added per line) */
- #define CONSOLE_LOG_MAX 1024
-
- /* the maximum size for a dropped text message */
- #define DROPPED_TEXT_MAX 64
-
- /* the maximum size allowed to be reserved for a record */
- #define LOG_LINE_MAX (CONSOLE_LOG_MAX - PREFIX_MAX)
-
#define LOG_LEVEL(v) ((v) & 0x07)
#define LOG_FACILITY(v) ((v) >> 3 & 0xff)
return len;
}
+ static bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
+ bool is_extended, bool may_supress);
+
/* /dev/kmsg - userspace message inject/listen interface */
struct devkmsg_user {
atomic64_t seq;
struct ratelimit_state rs;
struct mutex lock;
- char buf[CONSOLE_EXT_LOG_MAX];
-
- struct printk_info info;
- char text_buf[CONSOLE_EXT_LOG_MAX];
- struct printk_record record;
+ struct printk_buffers pbufs;
};
static __printf(3, 4) __cold
size_t len = iov_iter_count(from);
ssize_t ret = len;
- if (!user || len > LOG_LINE_MAX)
+ if (!user || len > PRINTKRB_RECORD_MAX)
return -EINVAL;
/* Ignore when user logging is disabled. */
size_t count, loff_t *ppos)
{
struct devkmsg_user *user = file->private_data;
- struct printk_record *r = &user->record;
- size_t len;
+ char *outbuf = &user->pbufs.outbuf[0];
+ struct printk_message pmsg = {
+ .pbufs = &user->pbufs,
+ };
ssize_t ret;
if (!user)
if (ret)
return ret;
- if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) {
+ if (!printk_get_next_message(&pmsg, atomic64_read(&user->seq), true, false)) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
goto out;
* This pairs with __wake_up_klogd:A.
*/
ret = wait_event_interruptible(log_wait,
- prb_read_valid(prb,
- atomic64_read(&user->seq), r)); /* LMM(devkmsg_read:A) */
+ printk_get_next_message(&pmsg, atomic64_read(&user->seq), true,
+ false)); /* LMM(devkmsg_read:A) */
if (ret)
goto out;
}
- if (r->info->seq != atomic64_read(&user->seq)) {
+ if (pmsg.dropped) {
/* our last seen message is gone, return error and reset */
- atomic64_set(&user->seq, r->info->seq);
+ atomic64_set(&user->seq, pmsg.seq);
ret = -EPIPE;
goto out;
}
- len = info_print_ext_header(user->buf, sizeof(user->buf), r->info);
- len += msg_print_ext_body(user->buf + len, sizeof(user->buf) - len,
- &r->text_buf[0], r->info->text_len,
- &r->info->dev_info);
-
- atomic64_set(&user->seq, r->info->seq + 1);
+ atomic64_set(&user->seq, pmsg.seq + 1);
- if (len > count) {
+ if (pmsg.outbuf_len > count) {
ret = -EINVAL;
goto out;
}
- if (copy_to_user(buf, user->buf, len)) {
+ if (copy_to_user(buf, outbuf, pmsg.outbuf_len)) {
ret = -EFAULT;
goto out;
}
- ret = len;
+ ret = pmsg.outbuf_len;
out:
mutex_unlock(&user->lock);
return ret;
mutex_init(&user->lock);
- prb_rec_init_rd(&user->record, &user->info,
- &user->text_buf[0], sizeof(user->text_buf));
-
atomic64_set(&user->seq, prb_first_valid_seq(prb));
file->private_data = user;
return prb_record_text_space(&e);
}
- static char setup_text_buf[LOG_LINE_MAX] __initdata;
+ static char setup_text_buf[PRINTKRB_RECORD_MAX] __initdata;
void __init setup_log_buf(int early)
{
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];
+ char prefix[PRINTK_PREFIX_MAX];
bool truncated = false;
size_t prefix_len;
size_t line_len;
unsigned int line_count,
bool syslog, bool time)
{
- char prefix[PREFIX_MAX];
+ char prefix[PRINTK_PREFIX_MAX];
size_t prefix_len;
prefix_len = info_print_prefix(info, syslog, time, prefix);
int len = 0;
u64 seq;
- text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
+ text = kmalloc(PRINTK_MESSAGE_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
- prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
+ prb_rec_init_rd(&r, &info, text, PRINTK_MESSAGE_MAX);
mutex_lock(&syslog_lock);
u64 seq;
bool time;
- text = kmalloc(CONSOLE_LOG_MAX, GFP_KERNEL);
+ text = kmalloc(PRINTK_MESSAGE_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
seq = find_first_fitting_seq(latched_seq_read_nolock(&clear_seq), -1,
size, true, time);
- prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
+ prb_rec_init_rd(&r, &info, text, PRINTK_MESSAGE_MAX);
len = 0;
prb_for_each_record(seq, prb, seq, &r) {
/**
* console_lock_spinning_disable_and_check - mark end of code where another
* thread was able to busy wait and check if there is a waiter
+ * @cookie: cookie returned from console_srcu_read_lock()
*
* This is called at the end of the section where spinning is allowed.
* It has two functions. First, it is a signal that it is no longer
return 1;
}
- /*
- * Call the specified console driver, asking it to write out the specified
- * text and length. If @dropped_text is non-NULL and any records have been
- * dropped, a dropped message will be written out first.
- */
- static void call_console_driver(struct console *con, const char *text, size_t len,
- char *dropped_text)
- {
- size_t dropped_len;
-
- if (con->dropped && dropped_text) {
- dropped_len = snprintf(dropped_text, DROPPED_TEXT_MAX,
- "** %lu printk messages dropped **\n",
- con->dropped);
- con->dropped = 0;
- con->write(con, dropped_text, dropped_len);
- }
-
- con->write(con, text, len);
- }
-
/*
* Recursion is tracked separately on each CPU. If NMIs are supported, an
* additional NMI context per CPU is also separately tracked. Until per-CPU
}
}
- trace_console_rcuidle(text, text_len);
+ trace_console(text, text_len);
return text_len;
}
reserve_size = vsnprintf(&prefix_buf[0], sizeof(prefix_buf), fmt, args2) + 1;
va_end(args2);
- if (reserve_size > LOG_LINE_MAX)
- reserve_size = LOG_LINE_MAX;
+ if (reserve_size > PRINTKRB_RECORD_MAX)
+ reserve_size = PRINTKRB_RECORD_MAX;
/* Extract log level or control flags. */
if (facility == 0)
if (flags & LOG_CONT) {
prb_rec_init_wr(&r, reserve_size);
- if (prb_reserve_in_last(&e, prb, &r, caller_id, LOG_LINE_MAX)) {
+ if (prb_reserve_in_last(&e, prb, &r, caller_id, PRINTKRB_RECORD_MAX)) {
text_len = printk_sprint(&r.text_buf[r.info->text_len], reserve_size,
facility, &flags, fmt, args);
r.info->text_len += text_len;
#else /* CONFIG_PRINTK */
- #define CONSOLE_LOG_MAX 0
- #define DROPPED_TEXT_MAX 0
#define printk_time false
#define prb_read_valid(rb, seq, r) false
struct dev_printk_info *dev_info) { return 0; }
static void console_lock_spinning_enable(void) { }
static int console_lock_spinning_disable_and_check(int cookie) { return 0; }
- static void call_console_driver(struct console *con, const char *text, size_t len,
- char *dropped_text)
- {
- }
static bool suppress_message_printing(int level) { return false; }
static bool pr_flush(int timeout_ms, bool reset_on_progress) { return true; }
static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progress) { return true; }
}
/*
- * Print one record for the given console. The record printed is whatever
- * record is the next available record for the given console.
+ * Prepend the message in @pmsg->pbufs->outbuf with a "dropped message". This
+ * is achieved by shifting the existing message over and inserting the dropped
+ * message.
+ *
+ * @pmsg is the printk message to prepend.
*
- * @text is a buffer of size CONSOLE_LOG_MAX.
+ * @dropped is the dropped count to report in the dropped message.
*
- * If extended messages should be printed, @ext_text is a buffer of size
- * CONSOLE_EXT_LOG_MAX. Otherwise @ext_text must be NULL.
+ * If the message text in @pmsg->pbufs->outbuf does not have enough space for
+ * the dropped message, the message text will be sufficiently truncated.
*
- * If dropped messages should be printed, @dropped_text is a buffer of size
- * DROPPED_TEXT_MAX. Otherwise @dropped_text must be NULL.
+ * If @pmsg->pbufs->outbuf is modified, @pmsg->outbuf_len is updated.
+ */
+ #ifdef CONFIG_PRINTK
+ static void console_prepend_dropped(struct printk_message *pmsg, unsigned long dropped)
+ {
+ struct printk_buffers *pbufs = pmsg->pbufs;
+ const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf);
+ const size_t outbuf_sz = sizeof(pbufs->outbuf);
+ char *scratchbuf = &pbufs->scratchbuf[0];
+ char *outbuf = &pbufs->outbuf[0];
+ size_t len;
+
+ len = scnprintf(scratchbuf, scratchbuf_sz,
+ "** %lu printk messages dropped **\n", dropped);
+
+ /*
+ * Make sure outbuf is sufficiently large before prepending.
+ * Keep at least the prefix when the message must be truncated.
+ * It is a rather theoretical problem when someone tries to
+ * use a minimalist buffer.
+ */
+ if (WARN_ON_ONCE(len + PRINTK_PREFIX_MAX >= outbuf_sz))
+ return;
+
+ if (pmsg->outbuf_len + len >= outbuf_sz) {
+ /* Truncate the message, but keep it terminated. */
+ pmsg->outbuf_len = outbuf_sz - (len + 1);
+ outbuf[pmsg->outbuf_len] = 0;
+ }
+
+ memmove(outbuf + len, outbuf, pmsg->outbuf_len + 1);
+ memcpy(outbuf, scratchbuf, len);
+ pmsg->outbuf_len += len;
+ }
+ #else
+ #define console_prepend_dropped(pmsg, dropped)
+ #endif /* CONFIG_PRINTK */
+
+ /*
+ * Read and format the specified record (or a later record if the specified
+ * record is not available).
+ *
+ * @pmsg will contain the formatted result. @pmsg->pbufs must point to a
+ * struct printk_buffers.
+ *
+ * @seq is the record to read and format. If it is not available, the next
+ * valid record is read.
+ *
+ * @is_extended specifies if the message should be formatted for extended
+ * console output.
+ *
+ * @may_supress specifies if records may be skipped based on loglevel.
+ *
+ * Returns false if no record is available. Otherwise true and all fields
+ * of @pmsg are valid. (See the documentation of struct printk_message
+ * for information about the @pmsg fields.)
+ */
+ static bool printk_get_next_message(struct printk_message *pmsg, u64 seq,
+ bool is_extended, bool may_suppress)
+ {
+ static int panic_console_dropped;
+
+ struct printk_buffers *pbufs = pmsg->pbufs;
+ const size_t scratchbuf_sz = sizeof(pbufs->scratchbuf);
+ const size_t outbuf_sz = sizeof(pbufs->outbuf);
+ char *scratchbuf = &pbufs->scratchbuf[0];
+ char *outbuf = &pbufs->outbuf[0];
+ struct printk_info info;
+ struct printk_record r;
+ size_t len = 0;
+
+ /*
+ * Formatting extended messages requires a separate buffer, so use the
+ * scratch buffer to read in the ringbuffer text.
+ *
+ * Formatting normal messages is done in-place, so read the ringbuffer
+ * text directly into the output buffer.
+ */
+ if (is_extended)
+ prb_rec_init_rd(&r, &info, scratchbuf, scratchbuf_sz);
+ else
+ prb_rec_init_rd(&r, &info, outbuf, outbuf_sz);
+
+ if (!prb_read_valid(prb, seq, &r))
+ return false;
+
+ pmsg->seq = r.info->seq;
+ pmsg->dropped = r.info->seq - seq;
+
+ /*
+ * Check for dropped messages in panic here so that printk
+ * suppression can occur as early as possible if necessary.
+ */
+ if (pmsg->dropped &&
+ panic_in_progress() &&
+ panic_console_dropped++ > 10) {
+ suppress_panic_printk = 1;
+ pr_warn_once("Too many dropped messages. Suppress messages on non-panic CPUs to prevent livelock.\n");
+ }
+
+ /* Skip record that has level above the console loglevel. */
+ if (may_suppress && suppress_message_printing(r.info->level))
+ goto out;
+
+ if (is_extended) {
+ len = info_print_ext_header(outbuf, outbuf_sz, r.info);
+ len += msg_print_ext_body(outbuf + len, outbuf_sz - len,
+ &r.text_buf[0], r.info->text_len, &r.info->dev_info);
+ } else {
+ len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time);
+ }
+ out:
+ pmsg->outbuf_len = len;
+ return true;
+ }
+
+ /*
+ * Print one record for the given console. The record printed is whatever
+ * record is the next available record for the given console.
*
* @handover will be set to true if a printk waiter has taken over the
* console_lock, in which case the caller is no longer holding both the
*
* Requires the console_lock and the SRCU read lock.
*/
- static bool console_emit_next_record(struct console *con, char *text, char *ext_text,
- char *dropped_text, bool *handover, int cookie)
+ static bool console_emit_next_record(struct console *con, bool *handover, int cookie)
{
- static int panic_console_dropped;
- struct printk_info info;
- struct printk_record r;
- unsigned long flags;
- char *write_text;
- size_t len;
+ static struct printk_buffers pbufs;
- prb_rec_init_rd(&r, &info, text, CONSOLE_LOG_MAX);
+ bool is_extended = console_srcu_read_flags(con) & CON_EXTENDED;
+ char *outbuf = &pbufs.outbuf[0];
+ struct printk_message pmsg = {
+ .pbufs = &pbufs,
+ };
+ unsigned long flags;
*handover = false;
- if (!prb_read_valid(prb, con->seq, &r))
+ if (!printk_get_next_message(&pmsg, con->seq, is_extended, true))
return false;
- if (con->seq != r.info->seq) {
- con->dropped += r.info->seq - con->seq;
- con->seq = r.info->seq;
- if (panic_in_progress() && panic_console_dropped++ > 10) {
- suppress_panic_printk = 1;
- pr_warn_once("Too many dropped messages. Suppress messages on non-panic CPUs to prevent livelock.\n");
- }
- }
+ con->dropped += pmsg.dropped;
- /* Skip record that has level above the console loglevel. */
- if (suppress_message_printing(r.info->level)) {
- con->seq++;
+ /* Skip messages of formatted length 0. */
+ if (pmsg.outbuf_len == 0) {
+ con->seq = pmsg.seq + 1;
goto skip;
}
- if (ext_text) {
- write_text = ext_text;
- len = info_print_ext_header(ext_text, CONSOLE_EXT_LOG_MAX, r.info);
- len += msg_print_ext_body(ext_text + len, CONSOLE_EXT_LOG_MAX - len,
- &r.text_buf[0], r.info->text_len, &r.info->dev_info);
- } else {
- write_text = text;
- len = record_print_text(&r, console_msg_format & MSG_FORMAT_SYSLOG, printk_time);
+ if (con->dropped && !is_extended) {
+ console_prepend_dropped(&pmsg, con->dropped);
+ con->dropped = 0;
}
/*
printk_safe_enter_irqsave(flags);
console_lock_spinning_enable();
- stop_critical_timings(); /* don't trace print latency */
- call_console_driver(con, write_text, len, dropped_text);
+ /* Do not trace print latency. */
+ stop_critical_timings();
+
+ /* Write everything out to the hardware. */
+ con->write(con, outbuf, pmsg.outbuf_len);
+
start_critical_timings();
- con->seq++;
+ con->seq = pmsg.seq + 1;
*handover = console_lock_spinning_disable_and_check(cookie);
printk_safe_exit_irqrestore(flags);
*/
static bool console_flush_all(bool do_cond_resched, u64 *next_seq, bool *handover)
{
- static char dropped_text[DROPPED_TEXT_MAX];
- static char ext_text[CONSOLE_EXT_LOG_MAX];
- static char text[CONSOLE_LOG_MAX];
bool any_usable = false;
struct console *con;
bool any_progress;
continue;
any_usable = true;
- if (console_srcu_read_flags(con) & CON_EXTENDED) {
- /* Extended consoles do not print "dropped messages". */
- progress = console_emit_next_record(con, &text[0],
- &ext_text[0], NULL,
- handover, cookie);
- } else {
- progress = console_emit_next_record(con, &text[0],
- NULL, &dropped_text[0],
- handover, cookie);
- }
+ progress = console_emit_next_record(con, handover, cookie);
/*
* If a handover has occurred, the SRCU read lock
projects / J-linux.git / commitdiff