#include "console_cmdline.h"
#include "braille.h"
-/* printk's without a loglevel use this.. */
-#define DEFAULT_MESSAGE_LOGLEVEL CONFIG_DEFAULT_MESSAGE_LOGLEVEL
-
-/* We show everything that is MORE important than this.. */
-#define MINIMUM_CONSOLE_LOGLEVEL 1 /* Minimum loglevel we let people use */
-#define DEFAULT_CONSOLE_LOGLEVEL 7 /* anything MORE serious than KERN_DEBUG */
-
int console_printk[4] = {
- DEFAULT_CONSOLE_LOGLEVEL, /* console_loglevel */
+ CONSOLE_LOGLEVEL_DEFAULT, /* console_loglevel */
DEFAULT_MESSAGE_LOGLEVEL, /* default_message_loglevel */
- MINIMUM_CONSOLE_LOGLEVEL, /* minimum_console_loglevel */
- DEFAULT_CONSOLE_LOGLEVEL, /* default_console_loglevel */
+ CONSOLE_LOGLEVEL_MIN, /* minimum_console_loglevel */
+ CONSOLE_LOGLEVEL_DEFAULT, /* default_console_loglevel */
};
+/* Deferred messaged from sched code are marked by this special level */
+#define SCHED_MESSAGE_LOGLEVEL -2
+
/*
* Low level drivers may need that to know if they can schedule in
* their unblank() callback or not. So let's export it.
};
#endif
+/*
+ * Helper macros to handle lockdep when locking/unlocking console_sem. We use
+ * macros instead of functions so that _RET_IP_ contains useful information.
+ */
+#define down_console_sem() do { \
+ down(&console_sem);\
+ mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);\
+} while (0)
+
+static int __down_trylock_console_sem(unsigned long ip)
+{
+ if (down_trylock(&console_sem))
+ return 1;
+ mutex_acquire(&console_lock_dep_map, 0, 1, ip);
+ return 0;
+}
+#define down_trylock_console_sem() __down_trylock_console_sem(_RET_IP_)
+
+#define up_console_sem() do { \
+ mutex_release(&console_lock_dep_map, 1, _RET_IP_);\
+ up(&console_sem);\
+} while (0)
+
/*
* This is used for debugging the mess that is the VT code by
* keeping track if we have the console semaphore held. It's
};
/*
- * The logbuf_lock protects kmsg buffer, indices, counters. It is also
- * used in interesting ways to provide interlocking in console_unlock();
+ * The logbuf_lock protects kmsg buffer, indices, counters. This can be taken
+ * within the scheduler's rq lock. It must be released before calling
+ * console_unlock() or anything else that might wake up a process.
*/
static DEFINE_RAW_SPINLOCK(logbuf_lock);
static char *log_buf = __log_buf;
static u32 log_buf_len = __LOG_BUF_LEN;
-/* cpu currently holding logbuf_lock */
-static volatile unsigned int logbuf_cpu = UINT_MAX;
-
/* human readable text of the record */
static char *log_text(const struct printk_log *msg)
{
return idx + msg->len;
}
-/* insert record into the buffer, discard old ones, update heads */
-static void log_store(int facility, int level,
- enum log_flags flags, u64 ts_nsec,
- const char *dict, u16 dict_len,
- const char *text, u16 text_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)
{
- struct printk_log *msg;
- u32 size, pad_len;
+ u32 free;
- /* number of '\0' padding bytes to next message */
- size = sizeof(struct printk_log) + text_len + dict_len;
- pad_len = (-size) & (LOG_ALIGN - 1);
- size += pad_len;
+ 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) {
- u32 free;
+ if (logbuf_has_space(msg_size, false))
+ return 0;
+ /* drop old messages until we have enough continuous space */
+ log_first_idx = log_next(log_first_idx);
+ log_first_seq++;
+ }
- if (log_next_idx > log_first_idx)
- free = max(log_buf_len - log_next_idx, log_first_idx);
- else
- free = log_first_idx - log_next_idx;
+ /* sequence numbers are equal, so the log buffer is empty */
+ if (logbuf_has_space(msg_size, true))
+ return 0;
- if (free >= size + sizeof(struct printk_log))
- break;
+ return -ENOMEM;
+}
- /* drop old messages until we have enough contiuous space */
- log_first_idx = log_next(log_first_idx);
- log_first_seq++;
+/* 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
+ * when the index points to the middle.
+ */
+#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)
+{
+ /*
+ * 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 */
+ *trunc_msg_len = strlen(trunc_msg);
+ /* 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 */
+static int log_store(int facility, int level,
+ enum log_flags flags, u64 ts_nsec,
+ const char *dict, u16 dict_len,
+ const char *text, u16 text_len)
+{
+ struct printk_log *msg;
+ u32 size, pad_len;
+ u16 trunc_msg_len = 0;
+
+ /* number of '\0' padding bytes to next message */
+ size = msg_used_size(text_len, dict_len, &pad_len);
+
+ if (log_make_free_space(size)) {
+ /* truncate the message if it is too long for empty buffer */
+ size = truncate_msg(&text_len, &trunc_msg_len,
+ &dict_len, &pad_len);
+ /* survive when the log buffer is too small for trunc_msg */
+ if (log_make_free_space(size))
+ return 0;
}
if (log_next_idx + size + sizeof(struct printk_log) > log_buf_len) {
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;
/* insert message */
log_next_idx += msg->len;
log_next_seq++;
+
+ return msg->text_len;
}
#ifdef CONFIG_SECURITY_DMESG_RESTRICT
sema_init(&console_sem, 1);
}
-/* Check if we have any console registered that can be called early in boot. */
+/*
+ * Check if we have any console that is capable of printing while cpu is
+ * booting or shutting down. Requires console_sem.
+ */
static int have_callable_console(void)
{
struct console *con;
/*
* Can we actually use the console at this time on this cpu?
*
- * Console drivers may assume that per-cpu resources have
- * been allocated. So unless they're explicitly marked as
- * being able to cope (CON_ANYTIME) don't call them until
- * this CPU is officially up.
+ * Console drivers may assume that per-cpu resources have been allocated. So
+ * unless they're explicitly marked as being able to cope (CON_ANYTIME) don't
+ * call them until this CPU is officially up.
*/
static inline int can_use_console(unsigned int cpu)
{
* messages from a 'printk'. Return true (and with the
* console_lock held, and 'console_locked' set) if it
* is successful, false otherwise.
- *
- * This gets called with the 'logbuf_lock' spinlock held and
- * interrupts disabled. It should return with 'lockbuf_lock'
- * released but interrupts still disabled.
*/
-static int console_trylock_for_printk(unsigned int cpu)
- __releases(&logbuf_lock)
+static int console_trylock_for_printk(void)
{
- int retval = 0, wake = 0;
-
- if (console_trylock()) {
- retval = 1;
+ unsigned int cpu = smp_processor_id();
- /*
- * If we can't use the console, we need to release
- * the console semaphore by hand to avoid flushing
- * the buffer. We need to hold the console semaphore
- * in order to do this test safely.
- */
- if (!can_use_console(cpu)) {
- console_locked = 0;
- wake = 1;
- retval = 0;
- }
+ if (!console_trylock())
+ return 0;
+ /*
+ * If we can't use the console, we need to release the console
+ * semaphore by hand to avoid flushing the buffer. We need to hold the
+ * console semaphore in order to do this test safely.
+ */
+ if (!can_use_console(cpu)) {
+ console_locked = 0;
+ up_console_sem();
+ return 0;
}
- logbuf_cpu = UINT_MAX;
- raw_spin_unlock(&logbuf_lock);
- if (wake)
- up(&console_sem);
- return retval;
+ return 1;
}
int printk_delay_msec __read_mostly;
static int recursion_bug;
static char textbuf[LOG_LINE_MAX];
char *text = textbuf;
- size_t text_len;
+ size_t text_len = 0;
enum log_flags lflags = 0;
unsigned long flags;
int this_cpu;
int printed_len = 0;
+ bool in_sched = false;
+ /* cpu currently holding logbuf_lock in this function */
+ static volatile unsigned int logbuf_cpu = UINT_MAX;
+
+ if (level == SCHED_MESSAGE_LOGLEVEL) {
+ level = -1;
+ in_sched = true;
+ }
boot_delay_msec(level);
printk_delay();
*/
if (!oops_in_progress && !lockdep_recursing(current)) {
recursion_bug = 1;
- goto out_restore_irqs;
+ local_irq_restore(flags);
+ return 0;
}
zap_locks();
}
"BUG: recent printk recursion!";
recursion_bug = 0;
- printed_len += strlen(recursion_msg);
+ text_len = strlen(recursion_msg);
/* emit KERN_CRIT message */
- log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
- NULL, 0, recursion_msg, printed_len);
+ printed_len += log_store(0, 2, LOG_PREFIX|LOG_NEWLINE, 0,
+ NULL, 0, recursion_msg, text_len);
}
/*
* The printf needs to come first; we need the syslog
* prefix which might be passed-in as a parameter.
*/
- text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
+ if (in_sched)
+ text_len = scnprintf(text, sizeof(textbuf),
+ KERN_WARNING "[sched_delayed] ");
+
+ text_len += vscnprintf(text + text_len,
+ sizeof(textbuf) - text_len, fmt, args);
/* mark and strip a trailing newline */
if (text_len && text[text_len-1] == '\n') {
cont_flush(LOG_NEWLINE);
/* 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);
+ if (cont_add(facility, level, text, text_len))
+ printed_len += text_len;
+ else
+ printed_len += log_store(facility, level,
+ lflags | LOG_CONT, 0,
+ dict, dictlen, text, text_len);
} else {
bool stored = false;
cont_flush(LOG_NEWLINE);
}
- if (!stored)
- log_store(facility, level, lflags, 0,
- dict, dictlen, text, text_len);
+ if (stored)
+ printed_len += text_len;
+ else
+ printed_len += log_store(facility, level, lflags, 0,
+ dict, dictlen, text, text_len);
}
- printed_len += text_len;
+ logbuf_cpu = UINT_MAX;
+ raw_spin_unlock(&logbuf_lock);
+ lockdep_on();
+ local_irq_restore(flags);
+
+ /* If called from the scheduler, we can not call up(). */
+ if (in_sched)
+ return printed_len;
+
+ /*
+ * Disable preemption to avoid being preempted while holding
+ * console_sem which would prevent anyone from printing to console
+ */
+ preempt_disable();
/*
* Try to acquire and then immediately release the console semaphore.
* The release will print out buffers and wake up /dev/kmsg and syslog()
* users.
- *
- * The console_trylock_for_printk() function will release 'logbuf_lock'
- * regardless of whether it actually gets the console semaphore or not.
*/
- if (console_trylock_for_printk(this_cpu))
+ if (console_trylock_for_printk())
console_unlock();
-
- lockdep_on();
-out_restore_irqs:
- local_irq_restore(flags);
+ preempt_enable();
return printed_len;
}
printk("Suspending console(s) (use no_console_suspend to debug)\n");
console_lock();
console_suspended = 1;
- up(&console_sem);
- mutex_release(&console_lock_dep_map, 1, _RET_IP_);
+ up_console_sem();
}
void resume_console(void)
{
if (!console_suspend_enabled)
return;
- down(&console_sem);
- mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
+ down_console_sem();
console_suspended = 0;
console_unlock();
}
{
might_sleep();
- down(&console_sem);
+ down_console_sem();
if (console_suspended)
return;
console_locked = 1;
console_may_schedule = 1;
- mutex_acquire(&console_lock_dep_map, 0, 0, _RET_IP_);
}
EXPORT_SYMBOL(console_lock);
*/
int console_trylock(void)
{
- if (down_trylock(&console_sem))
+ if (down_trylock_console_sem())
return 0;
if (console_suspended) {
- up(&console_sem);
+ up_console_sem();
return 0;
}
console_locked = 1;
console_may_schedule = 0;
- mutex_acquire(&console_lock_dep_map, 0, 1, _RET_IP_);
return 1;
}
EXPORT_SYMBOL(console_trylock);
bool retry;
if (console_suspended) {
- up(&console_sem);
+ up_console_sem();
return;
}
}
if (console_seq < log_first_seq) {
+ len = sprintf(text, "** %u printk messages dropped ** ",
+ (unsigned)(log_first_seq - console_seq));
+
/* messages are gone, move to first one */
console_seq = log_first_seq;
console_idx = log_first_idx;
console_prev = 0;
+ } else {
+ len = 0;
}
skip:
if (console_seq == log_next_seq)
}
level = msg->level;
- len = msg_print_text(msg, console_prev, false,
- text, sizeof(text));
+ len += msg_print_text(msg, console_prev, false,
+ text + len, sizeof(text) - len);
console_idx = log_next(console_idx);
console_seq++;
console_prev = msg->flags;
local_irq_restore(flags);
}
console_locked = 0;
- mutex_release(&console_lock_dep_map, 1, _RET_IP_);
/* Release the exclusive_console once it is used */
if (unlikely(exclusive_console))
raw_spin_unlock(&logbuf_lock);
- up(&console_sem);
+ up_console_sem();
/*
* Someone could have filled up the buffer again, so re-check if there's
* oops_in_progress is set to 1..
*/
if (oops_in_progress) {
- if (down_trylock(&console_sem) != 0)
+ if (down_trylock_console_sem() != 0)
return;
} else
console_lock();
/*
* Delayed printk version, for scheduler-internal messages:
*/
-#define PRINTK_BUF_SIZE 512
-
#define PRINTK_PENDING_WAKEUP 0x01
-#define PRINTK_PENDING_SCHED 0x02
+#define PRINTK_PENDING_OUTPUT 0x02
static DEFINE_PER_CPU(int, printk_pending);
-static DEFINE_PER_CPU(char [PRINTK_BUF_SIZE], printk_sched_buf);
static void wake_up_klogd_work_func(struct irq_work *irq_work)
{
int pending = __this_cpu_xchg(printk_pending, 0);
- if (pending & PRINTK_PENDING_SCHED) {
- char *buf = __get_cpu_var(printk_sched_buf);
- pr_warn("[sched_delayed] %s", buf);
+ if (pending & PRINTK_PENDING_OUTPUT) {
+ /* If trylock fails, someone else is doing the printing */
+ if (console_trylock())
+ console_unlock();
}
if (pending & PRINTK_PENDING_WAKEUP)
preempt_enable();
}
-int printk_sched(const char *fmt, ...)
+int printk_deferred(const char *fmt, ...)
{
- unsigned long flags;
va_list args;
- char *buf;
int r;
- local_irq_save(flags);
- buf = __get_cpu_var(printk_sched_buf);
-
+ preempt_disable();
va_start(args, fmt);
- r = vsnprintf(buf, PRINTK_BUF_SIZE, fmt, args);
+ r = vprintk_emit(0, SCHED_MESSAGE_LOGLEVEL, NULL, 0, fmt, args);
va_end(args);
- __this_cpu_or(printk_pending, PRINTK_PENDING_SCHED);
+ __this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
irq_work_queue(&__get_cpu_var(wake_up_klogd_work));
- local_irq_restore(flags);
+ preempt_enable();
return r;
}
projects / karo-tx-linux.git / blobdiff