extern void panic_flush_kmsg_end(void)
{
- printk_safe_flush_on_panic();
kmsg_dump(KMSG_DUMP_PANIC);
bust_spinlocks(0);
debug_locks_off();
wd_smp_unlock(&flags);
- printk_safe_flush();
- /*
- * printk_safe_flush() seems to require another print
- * before anything actually goes out to console.
- */
if (sysctl_hardlockup_all_cpu_backtrace)
trigger_allbutself_cpu_backtrace();
void show_regs_print_info(const char *log_lvl);
extern asmlinkage void dump_stack_lvl(const char *log_lvl) __cold;
extern asmlinkage void dump_stack(void) __cold;
-extern void printk_safe_flush(void);
-extern void printk_safe_flush_on_panic(void);
#else
static inline __printf(1, 0)
int vprintk(const char *s, va_list args)
static inline void dump_stack(void)
{
}
-
-static inline void printk_safe_flush(void)
-{
-}
-
-static inline void printk_safe_flush_on_panic(void)
-{
-}
#endif
#ifdef CONFIG_SMP
old_cpu = atomic_cmpxchg(&panic_cpu, PANIC_CPU_INVALID, this_cpu);
if (old_cpu == PANIC_CPU_INVALID) {
/* This is the 1st CPU which comes here, so go ahead. */
- printk_safe_flush_on_panic();
__crash_kexec(regs);
/*
* Bypass the panic_cpu check and call __crash_kexec directly.
*/
if (!_crash_kexec_post_notifiers) {
- printk_safe_flush_on_panic();
__crash_kexec(NULL);
/*
*/
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
- /* Call flush even twice. It tries harder with a single online CPU */
- printk_safe_flush_on_panic();
kmsg_dump(KMSG_DUMP_PANIC);
/*
void __printk_safe_enter(void);
void __printk_safe_exit(void);
-void printk_safe_init(void);
bool printk_percpu_data_ready(void);
#define printk_safe_enter_irqsave(flags) \
local_irq_restore(flags); \
} while (0)
-#define printk_safe_enter_irq() \
- do { \
- local_irq_disable(); \
- __printk_safe_enter(); \
- } while (0)
-
-#define printk_safe_exit_irq() \
- do { \
- __printk_safe_exit(); \
- local_irq_enable(); \
- } while (0)
-
void defer_console_output(void);
#else
#define printk_safe_enter_irqsave(flags) local_irq_save(flags)
#define printk_safe_exit_irqrestore(flags) local_irq_restore(flags)
-#define printk_safe_enter_irq() local_irq_disable()
-#define printk_safe_exit_irq() local_irq_enable()
-
-static inline void printk_safe_init(void) { }
static inline bool printk_percpu_data_ready(void) { return false; }
#endif /* CONFIG_PRINTK */
if (ret)
return ret;
- printk_safe_enter_irq();
if (!prb_read_valid(prb, atomic64_read(&user->seq), r)) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
- printk_safe_exit_irq();
goto out;
}
- printk_safe_exit_irq();
ret = wait_event_interruptible(log_wait,
prb_read_valid(prb, atomic64_read(&user->seq), r));
if (ret)
goto out;
- printk_safe_enter_irq();
}
if (r->info->seq != atomic64_read(&user->seq)) {
/* our last seen message is gone, return error and reset */
atomic64_set(&user->seq, r->info->seq);
ret = -EPIPE;
- printk_safe_exit_irq();
goto out;
}
&r->info->dev_info);
atomic64_set(&user->seq, r->info->seq + 1);
- printk_safe_exit_irq();
if (len > count) {
ret = -EINVAL;
if (offset)
return -ESPIPE;
- printk_safe_enter_irq();
switch (whence) {
case SEEK_SET:
/* the first record */
default:
ret = -EINVAL;
}
- printk_safe_exit_irq();
return ret;
}
poll_wait(file, &log_wait, wait);
- printk_safe_enter_irq();
if (prb_read_valid_info(prb, atomic64_read(&user->seq), &info, NULL)) {
/* return error when data has vanished underneath us */
if (info.seq != atomic64_read(&user->seq))
else
ret = EPOLLIN|EPOLLRDNORM;
}
- printk_safe_exit_irq();
return ret;
}
prb_rec_init_rd(&user->record, &user->info,
&user->text_buf[0], sizeof(user->text_buf));
- printk_safe_enter_irq();
atomic64_set(&user->seq, prb_first_valid_seq(prb));
- printk_safe_exit_irq();
file->private_data = user;
return 0;
static void __init set_percpu_data_ready(void)
{
- printk_safe_init();
- /* Make sure we set this flag only after printk_safe() init is done */
- barrier();
__printk_percpu_data_ready = true;
}
struct prb_desc *new_descs;
struct printk_info info;
struct printk_record r;
+ unsigned int text_size;
size_t new_descs_size;
size_t new_infos_size;
unsigned long flags;
new_descs, ilog2(new_descs_count),
new_infos);
- printk_safe_enter_irqsave(flags);
+ local_irq_save(flags);
log_buf_len = new_log_buf_len;
log_buf = new_log_buf;
new_log_buf_len = 0;
free = __LOG_BUF_LEN;
- prb_for_each_record(0, &printk_rb_static, seq, &r)
- free -= add_to_rb(&printk_rb_dynamic, &r);
+ prb_for_each_record(0, &printk_rb_static, seq, &r) {
+ text_size = add_to_rb(&printk_rb_dynamic, &r);
+ if (text_size > free)
+ free = 0;
+ else
+ free -= text_size;
+ }
- /*
- * This is early enough that everything is still running on the
- * boot CPU and interrupts are disabled. So no new messages will
- * appear during the transition to the dynamic buffer.
- */
prb = &printk_rb_dynamic;
- printk_safe_exit_irqrestore(flags);
+ local_irq_restore(flags);
+
+ /*
+ * Copy any remaining messages that might have appeared from
+ * NMI context after copying but before switching to the
+ * dynamic buffer.
+ */
+ prb_for_each_record(seq, &printk_rb_static, seq, &r) {
+ text_size = add_to_rb(&printk_rb_dynamic, &r);
+ if (text_size > free)
+ free = 0;
+ else
+ free -= text_size;
+ }
if (seq != prb_next_seq(&printk_rb_static)) {
pr_err("dropped %llu messages\n",
size_t n;
size_t skip;
- printk_safe_enter_irq();
- raw_spin_lock(&syslog_lock);
+ raw_spin_lock_irq(&syslog_lock);
if (!prb_read_valid(prb, syslog_seq, &r)) {
- raw_spin_unlock(&syslog_lock);
- printk_safe_exit_irq();
+ raw_spin_unlock_irq(&syslog_lock);
break;
}
if (r.info->seq != syslog_seq) {
syslog_partial += n;
} else
n = 0;
- raw_spin_unlock(&syslog_lock);
- printk_safe_exit_irq();
+ raw_spin_unlock_irq(&syslog_lock);
if (!n)
break;
return -ENOMEM;
time = printk_time;
- printk_safe_enter_irq();
/*
* Find first record that fits, including all following records,
* into the user-provided buffer for this dump.
break;
}
- printk_safe_exit_irq();
if (copy_to_user(buf + len, text, textlen))
len = -EFAULT;
else
len += textlen;
- printk_safe_enter_irq();
if (len < 0)
break;
}
if (clear) {
- raw_spin_lock(&syslog_lock);
+ raw_spin_lock_irq(&syslog_lock);
latched_seq_write(&clear_seq, seq);
- raw_spin_unlock(&syslog_lock);
+ raw_spin_unlock_irq(&syslog_lock);
}
- printk_safe_exit_irq();
kfree(text);
return len;
static void syslog_clear(void)
{
- printk_safe_enter_irq();
- raw_spin_lock(&syslog_lock);
+ raw_spin_lock_irq(&syslog_lock);
latched_seq_write(&clear_seq, prb_next_seq(prb));
- raw_spin_unlock(&syslog_lock);
- printk_safe_exit_irq();
+ raw_spin_unlock_irq(&syslog_lock);
}
/* Return a consistent copy of @syslog_seq. */
break;
/* Number of chars in the log buffer */
case SYSLOG_ACTION_SIZE_UNREAD:
- printk_safe_enter_irq();
- raw_spin_lock(&syslog_lock);
+ raw_spin_lock_irq(&syslog_lock);
if (!prb_read_valid_info(prb, syslog_seq, &info, NULL)) {
/* No unread messages. */
- raw_spin_unlock(&syslog_lock);
- printk_safe_exit_irq();
+ raw_spin_unlock_irq(&syslog_lock);
return 0;
}
if (info.seq != syslog_seq) {
}
error -= syslog_partial;
}
- raw_spin_unlock(&syslog_lock);
- printk_safe_exit_irq();
+ raw_spin_unlock_irq(&syslog_lock);
break;
/* Size of the log buffer */
case SYSLOG_ACTION_SIZE_BUFFER:
{
int printed_len;
bool in_sched = false;
- unsigned long flags;
/* Suppress unimportant messages after panic happens */
if (unlikely(suppress_printk))
boot_delay_msec(level);
printk_delay();
- printk_safe_enter_irqsave(flags);
printed_len = vprintk_store(facility, level, dev_info, fmt, args);
- printk_safe_exit_irqrestore(flags);
/* If called from the scheduler, we can not call up(). */
if (!in_sched) {
for (;;) {
size_t ext_len = 0;
+ int handover;
size_t len;
- printk_safe_enter_irqsave(flags);
skip:
if (!prb_read_valid(prb, console_seq, &r))
break;
* were to occur on another CPU, it may wait for this one to
* finish. This task can not be preempted if there is a
* waiter waiting to take over.
+ *
+ * Interrupts are disabled because the hand over to a waiter
+ * must not be interrupted until the hand over is completed
+ * (@console_waiter is cleared).
*/
+ printk_safe_enter_irqsave(flags);
console_lock_spinning_enable();
stop_critical_timings(); /* don't trace print latency */
call_console_drivers(ext_text, ext_len, text, len);
start_critical_timings();
- if (console_lock_spinning_disable_and_check()) {
- printk_safe_exit_irqrestore(flags);
- return;
- }
-
+ handover = console_lock_spinning_disable_and_check();
printk_safe_exit_irqrestore(flags);
+ if (handover)
+ return;
if (do_cond_resched)
cond_resched();
* flush, no worries.
*/
retry = prb_read_valid(prb, console_seq, NULL);
- printk_safe_exit_irqrestore(flags);
-
if (retry && console_trylock())
goto again;
}
console_trylock();
console_may_schedule = 0;
- if (mode == CONSOLE_REPLAY_ALL) {
- unsigned long flags;
-
- printk_safe_enter_irqsave(flags);
+ if (mode == CONSOLE_REPLAY_ALL)
console_seq = prb_first_valid_seq(prb);
- printk_safe_exit_irqrestore(flags);
- }
console_unlock();
}
struct printk_info info;
unsigned int line_count;
struct printk_record r;
- unsigned long flags;
size_t l = 0;
bool ret = false;
if (iter->cur_seq < min_seq)
iter->cur_seq = min_seq;
- printk_safe_enter_irqsave(flags);
prb_rec_init_rd(&r, &info, line, size);
/* Read text or count text lines? */
iter->cur_seq = r.info->seq + 1;
ret = true;
out:
- printk_safe_exit_irqrestore(flags);
if (len)
*len = l;
return ret;
u64 min_seq = latched_seq_read_nolock(&clear_seq);
struct printk_info info;
struct printk_record r;
- unsigned long flags;
u64 seq;
u64 next_seq;
size_t len = 0;
if (iter->cur_seq < min_seq)
iter->cur_seq = min_seq;
- printk_safe_enter_irqsave(flags);
if (prb_read_valid_info(prb, iter->cur_seq, &info, NULL)) {
if (info.seq != iter->cur_seq) {
/* messages are gone, move to first available one */
}
/* last entry */
- if (iter->cur_seq >= iter->next_seq) {
- printk_safe_exit_irqrestore(flags);
+ if (iter->cur_seq >= iter->next_seq)
goto out;
- }
/*
* Find first record that fits, including all following records,
iter->next_seq = next_seq;
ret = true;
- printk_safe_exit_irqrestore(flags);
out:
if (len_out)
*len_out = len;
*/
void kmsg_dump_rewind(struct kmsg_dump_iter *iter)
{
- unsigned long flags;
-
- printk_safe_enter_irqsave(flags);
iter->cur_seq = latched_seq_read_nolock(&clear_seq);
iter->next_seq = prb_next_seq(prb);
- printk_safe_exit_irqrestore(flags);
}
EXPORT_SYMBOL_GPL(kmsg_dump_rewind);
#include "internal.h"
-/*
- * In NMI and safe mode, printk() avoids taking locks. Instead,
- * it uses an alternative implementation that temporary stores
- * the strings into a per-CPU buffer. The content of the buffer
- * is later flushed into the main ring buffer via IRQ work.
- *
- * The alternative implementation is chosen transparently
- * by examining current printk() context mask stored in @printk_context
- * per-CPU variable.
- *
- * The implementation allows to flush the strings also from another CPU.
- * There are situations when we want to make sure that all buffers
- * were handled or when IRQs are blocked.
- */
-
-#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
- sizeof(atomic_t) - \
- sizeof(atomic_t) - \
- sizeof(struct irq_work))
-
-struct printk_safe_seq_buf {
- atomic_t len; /* length of written data */
- atomic_t message_lost;
- struct irq_work work; /* IRQ work that flushes the buffer */
- unsigned char buffer[SAFE_LOG_BUF_LEN];
-};
-
-static DEFINE_PER_CPU(struct printk_safe_seq_buf, safe_print_seq);
static DEFINE_PER_CPU(int, printk_context);
-static DEFINE_RAW_SPINLOCK(safe_read_lock);
-
-#ifdef CONFIG_PRINTK_NMI
-static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
-#endif
-
-/* Get flushed in a more safe context. */
-static void queue_flush_work(struct printk_safe_seq_buf *s)
-{
- if (printk_percpu_data_ready())
- irq_work_queue(&s->work);
-}
-
-/*
- * Add a message to per-CPU context-dependent buffer. NMI and printk-safe
- * have dedicated buffers, because otherwise printk-safe preempted by
- * NMI-printk would have overwritten the NMI messages.
- *
- * The messages are flushed from irq work (or from panic()), possibly,
- * from other CPU, concurrently with printk_safe_log_store(). Should this
- * happen, printk_safe_log_store() will notice the buffer->len mismatch
- * and repeat the write.
- */
-static __printf(2, 0) int printk_safe_log_store(struct printk_safe_seq_buf *s,
- const char *fmt, va_list args)
-{
- int add;
- size_t len;
- va_list ap;
-
-again:
- len = atomic_read(&s->len);
-
- /* The trailing '\0' is not counted into len. */
- if (len >= sizeof(s->buffer) - 1) {
- atomic_inc(&s->message_lost);
- queue_flush_work(s);
- return 0;
- }
-
- /*
- * Make sure that all old data have been read before the buffer
- * was reset. This is not needed when we just append data.
- */
- if (!len)
- smp_rmb();
-
- va_copy(ap, args);
- add = vscnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, ap);
- va_end(ap);
- if (!add)
- return 0;
-
- /*
- * Do it once again if the buffer has been flushed in the meantime.
- * Note that atomic_cmpxchg() is an implicit memory barrier that
- * makes sure that the data were written before updating s->len.
- */
- if (atomic_cmpxchg(&s->len, len, len + add) != len)
- goto again;
-
- queue_flush_work(s);
- return add;
-}
-
-static inline void printk_safe_flush_line(const char *text, int len)
-{
- /*
- * Avoid any console drivers calls from here, because we may be
- * in NMI or printk_safe context (when in panic). The messages
- * must go only into the ring buffer at this stage. Consoles will
- * get explicitly called later when a crashdump is not generated.
- */
- printk_deferred("%.*s", len, text);
-}
-
-/* printk part of the temporary buffer line by line */
-static int printk_safe_flush_buffer(const char *start, size_t len)
-{
- const char *c, *end;
- bool header;
-
- c = start;
- end = start + len;
- header = true;
-
- /* Print line by line. */
- while (c < end) {
- if (*c == '\n') {
- printk_safe_flush_line(start, c - start + 1);
- start = ++c;
- header = true;
- continue;
- }
-
- /* Handle continuous lines or missing new line. */
- if ((c + 1 < end) && printk_get_level(c)) {
- if (header) {
- c = printk_skip_level(c);
- continue;
- }
-
- printk_safe_flush_line(start, c - start);
- start = c++;
- header = true;
- continue;
- }
-
- header = false;
- c++;
- }
-
- /* Check if there was a partial line. Ignore pure header. */
- if (start < end && !header) {
- static const char newline[] = KERN_CONT "\n";
-
- printk_safe_flush_line(start, end - start);
- printk_safe_flush_line(newline, strlen(newline));
- }
-
- return len;
-}
-
-static void report_message_lost(struct printk_safe_seq_buf *s)
-{
- int lost = atomic_xchg(&s->message_lost, 0);
-
- if (lost)
- printk_deferred("Lost %d message(s)!\n", lost);
-}
-
-/*
- * Flush data from the associated per-CPU buffer. The function
- * can be called either via IRQ work or independently.
- */
-static void __printk_safe_flush(struct irq_work *work)
-{
- struct printk_safe_seq_buf *s =
- container_of(work, struct printk_safe_seq_buf, work);
- unsigned long flags;
- size_t len;
- int i;
-
- /*
- * The lock has two functions. First, one reader has to flush all
- * available message to make the lockless synchronization with
- * writers easier. Second, we do not want to mix messages from
- * different CPUs. This is especially important when printing
- * a backtrace.
- */
- raw_spin_lock_irqsave(&safe_read_lock, flags);
-
- i = 0;
-more:
- len = atomic_read(&s->len);
-
- /*
- * This is just a paranoid check that nobody has manipulated
- * the buffer an unexpected way. If we printed something then
- * @len must only increase. Also it should never overflow the
- * buffer size.
- */
- if ((i && i >= len) || len > sizeof(s->buffer)) {
- const char *msg = "printk_safe_flush: internal error\n";
-
- printk_safe_flush_line(msg, strlen(msg));
- len = 0;
- }
-
- if (!len)
- goto out; /* Someone else has already flushed the buffer. */
-
- /* Make sure that data has been written up to the @len */
- smp_rmb();
- i += printk_safe_flush_buffer(s->buffer + i, len - i);
-
- /*
- * Check that nothing has got added in the meantime and truncate
- * the buffer. Note that atomic_cmpxchg() is an implicit memory
- * barrier that makes sure that the data were copied before
- * updating s->len.
- */
- if (atomic_cmpxchg(&s->len, len, 0) != len)
- goto more;
-
-out:
- report_message_lost(s);
- raw_spin_unlock_irqrestore(&safe_read_lock, flags);
-}
-
-/**
- * printk_safe_flush - flush all per-cpu nmi buffers.
- *
- * The buffers are flushed automatically via IRQ work. This function
- * is useful only when someone wants to be sure that all buffers have
- * been flushed at some point.
- */
-void printk_safe_flush(void)
-{
- int cpu;
-
- for_each_possible_cpu(cpu) {
-#ifdef CONFIG_PRINTK_NMI
- __printk_safe_flush(&per_cpu(nmi_print_seq, cpu).work);
-#endif
- __printk_safe_flush(&per_cpu(safe_print_seq, cpu).work);
- }
-}
-
-/**
- * printk_safe_flush_on_panic - flush all per-cpu nmi buffers when the system
- * goes down.
- *
- * Similar to printk_safe_flush() but it can be called even in NMI context when
- * the system goes down. It does the best effort to get NMI messages into
- * the main ring buffer.
- *
- * Note that it could try harder when there is only one CPU online.
- */
-void printk_safe_flush_on_panic(void)
-{
- /*
- * Make sure that we could access the safe buffers.
- * Do not risk a double release when more CPUs are up.
- */
- if (raw_spin_is_locked(&safe_read_lock)) {
- if (num_online_cpus() > 1)
- return;
-
- debug_locks_off();
- raw_spin_lock_init(&safe_read_lock);
- }
-
- printk_safe_flush();
-}
-
#ifdef CONFIG_PRINTK_NMI
-/*
- * Safe printk() for NMI context. It uses a per-CPU buffer to
- * store the message. NMIs are not nested, so there is always only
- * one writer running. But the buffer might get flushed from another
- * CPU, so we need to be careful.
- */
-static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args)
-{
- struct printk_safe_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
-
- return printk_safe_log_store(s, fmt, args);
-}
-
void noinstr printk_nmi_enter(void)
{
this_cpu_add(printk_context, PRINTK_NMI_CONTEXT_OFFSET);
* Marks a code that might produce many messages in NMI context
* and the risk of losing them is more critical than eventual
* reordering.
- *
- * It has effect only when called in NMI context. Then printk()
- * will store the messages into the main logbuf directly.
*/
void printk_nmi_direct_enter(void)
{
this_cpu_and(printk_context, ~PRINTK_NMI_DIRECT_CONTEXT_MASK);
}
-#else
-
-static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args)
-{
- return 0;
-}
-
#endif /* CONFIG_PRINTK_NMI */
-/*
- * Lock-less printk(), to avoid deadlocks should the printk() recurse
- * into itself. It uses a per-CPU buffer to store the message, just like
- * NMI.
- */
-static __printf(1, 0) int vprintk_safe(const char *fmt, va_list args)
-{
- struct printk_safe_seq_buf *s = this_cpu_ptr(&safe_print_seq);
-
- return printk_safe_log_store(s, fmt, args);
-}
-
/* Can be preempted by NMI. */
void __printk_safe_enter(void)
{
* Use the main logbuf even in NMI. But avoid calling console
* drivers that might have their own locks.
*/
- if ((this_cpu_read(printk_context) & PRINTK_NMI_DIRECT_CONTEXT_MASK)) {
- unsigned long flags;
+ if (this_cpu_read(printk_context) &
+ (PRINTK_NMI_DIRECT_CONTEXT_MASK |
+ PRINTK_NMI_CONTEXT_MASK |
+ PRINTK_SAFE_CONTEXT_MASK)) {
int len;
- printk_safe_enter_irqsave(flags);
len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, fmt, args);
- printk_safe_exit_irqrestore(flags);
defer_console_output();
return len;
}
- /* Use extra buffer in NMI. */
- if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
- return vprintk_nmi(fmt, args);
-
- /* Use extra buffer to prevent a recursion deadlock in safe mode. */
- if (this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK)
- return vprintk_safe(fmt, args);
-
/* No obstacles. */
return vprintk_default(fmt, args);
}
EXPORT_SYMBOL(vprintk);
-
-void __init printk_safe_init(void)
-{
- int cpu;
-
- for_each_possible_cpu(cpu) {
- struct printk_safe_seq_buf *s;
-
- s = &per_cpu(safe_print_seq, cpu);
- init_irq_work(&s->work, __printk_safe_flush);
-
-#ifdef CONFIG_PRINTK_NMI
- s = &per_cpu(nmi_print_seq, cpu);
- init_irq_work(&s->work, __printk_safe_flush);
-#endif
- }
-
- /* Flush pending messages that did not have scheduled IRQ works. */
- printk_safe_flush();
-}
touch_softlockup_watchdog();
}
- /*
- * Force flush any remote buffers that might be stuck in IRQ context
- * and therefore could not run their irq_work.
- */
- printk_safe_flush();
-
clear_bit_unlock(0, &backtrace_flag);
put_cpu();
}
projects / users / hch / xfs.git / commitdiff