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-rw-r--r--kernel/printk/internal.h9
-rw-r--r--kernel/printk/printk.c181
-rw-r--r--kernel/printk/printk_safe.c58
-rw-r--r--kernel/trace/trace.c4
4 files changed, 148 insertions, 104 deletions
diff --git a/kernel/printk/internal.h b/kernel/printk/internal.h
index 2a7d04049af4..0f1898820cba 100644
--- a/kernel/printk/internal.h
+++ b/kernel/printk/internal.h
@@ -19,11 +19,16 @@
#ifdef CONFIG_PRINTK
#define PRINTK_SAFE_CONTEXT_MASK 0x3fffffff
-#define PRINTK_NMI_DEFERRED_CONTEXT_MASK 0x40000000
+#define PRINTK_NMI_DIRECT_CONTEXT_MASK 0x40000000
#define PRINTK_NMI_CONTEXT_MASK 0x80000000
extern raw_spinlock_t logbuf_lock;
+__printf(5, 0)
+int vprintk_store(int facility, int level,
+ const char *dict, size_t dictlen,
+ const char *fmt, va_list args);
+
__printf(1, 0) int vprintk_default(const char *fmt, va_list args);
__printf(1, 0) int vprintk_deferred(const char *fmt, va_list args);
__printf(1, 0) int vprintk_func(const char *fmt, va_list args);
@@ -54,6 +59,8 @@ void __printk_safe_exit(void);
local_irq_enable(); \
} while (0)
+void defer_console_output(void);
+
#else
__printf(1, 0) int vprintk_func(const char *fmt, va_list args) { return 0; }
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 247808333ba4..9a63aeeaaf5d 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -349,7 +349,7 @@ static int console_msg_format = MSG_FORMAT_DEFAULT;
*/
enum log_flags {
- LOG_NOCONS = 1, /* already flushed, do not print to console */
+ LOG_NOCONS = 1, /* suppress print, 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 */
@@ -1352,71 +1352,68 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
{
char *text;
int len = 0;
+ u64 next_seq;
+ u64 seq;
+ u32 idx;
text = kmalloc(LOG_LINE_MAX + PREFIX_MAX, GFP_KERNEL);
if (!text)
return -ENOMEM;
logbuf_lock_irq();
- if (buf) {
- u64 next_seq;
- u64 seq;
- u32 idx;
+ /*
+ * Find first record that fits, including all following records,
+ * into the user-provided buffer for this dump.
+ */
+ seq = clear_seq;
+ idx = clear_idx;
+ while (seq < log_next_seq) {
+ struct printk_log *msg = log_from_idx(idx);
- /*
- * Find first record that fits, including all following records,
- * into the user-provided buffer for this dump.
- */
- seq = clear_seq;
- idx = clear_idx;
- while (seq < log_next_seq) {
- struct printk_log *msg = log_from_idx(idx);
-
- len += msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- }
+ len += msg_print_text(msg, true, NULL, 0);
+ idx = log_next(idx);
+ seq++;
+ }
- /* move first record forward until length fits into the buffer */
- seq = clear_seq;
- idx = clear_idx;
- while (len > size && seq < log_next_seq) {
- struct printk_log *msg = log_from_idx(idx);
+ /* move first record forward until length fits into the buffer */
+ seq = clear_seq;
+ idx = clear_idx;
+ while (len > size && seq < log_next_seq) {
+ struct printk_log *msg = log_from_idx(idx);
- len -= msg_print_text(msg, true, NULL, 0);
- idx = log_next(idx);
- seq++;
- }
+ len -= msg_print_text(msg, true, NULL, 0);
+ idx = log_next(idx);
+ seq++;
+ }
- /* last message fitting into this dump */
- next_seq = log_next_seq;
+ /* last message fitting into this dump */
+ next_seq = log_next_seq;
- len = 0;
- while (len >= 0 && seq < next_seq) {
- struct printk_log *msg = log_from_idx(idx);
- int textlen;
+ len = 0;
+ while (len >= 0 && seq < next_seq) {
+ struct printk_log *msg = log_from_idx(idx);
+ int textlen;
- textlen = msg_print_text(msg, true, text,
- LOG_LINE_MAX + PREFIX_MAX);
- if (textlen < 0) {
- len = textlen;
- break;
- }
- idx = log_next(idx);
- seq++;
+ textlen = msg_print_text(msg, true, text,
+ LOG_LINE_MAX + PREFIX_MAX);
+ if (textlen < 0) {
+ len = textlen;
+ break;
+ }
+ idx = log_next(idx);
+ seq++;
- logbuf_unlock_irq();
- if (copy_to_user(buf + len, text, textlen))
- len = -EFAULT;
- else
- len += textlen;
- logbuf_lock_irq();
-
- if (seq < log_first_seq) {
- /* messages are gone, move to next one */
- seq = log_first_seq;
- idx = log_first_idx;
- }
+ logbuf_unlock_irq();
+ if (copy_to_user(buf + len, text, textlen))
+ len = -EFAULT;
+ else
+ len += textlen;
+ logbuf_lock_irq();
+
+ if (seq < log_first_seq) {
+ /* messages are gone, move to next one */
+ seq = log_first_seq;
+ idx = log_first_idx;
}
}
@@ -1430,6 +1427,14 @@ static int syslog_print_all(char __user *buf, int size, bool clear)
return len;
}
+static void syslog_clear(void)
+{
+ logbuf_lock_irq();
+ clear_seq = log_next_seq;
+ clear_idx = log_next_idx;
+ logbuf_unlock_irq();
+}
+
int do_syslog(int type, char __user *buf, int len, int source)
{
bool clear = false;
@@ -1474,7 +1479,7 @@ int do_syslog(int type, char __user *buf, int len, int source)
break;
/* Clear ring buffer */
case SYSLOG_ACTION_CLEAR:
- syslog_print_all(NULL, 0, true);
+ syslog_clear();
break;
/* Disable logging to console */
case SYSLOG_ACTION_CONSOLE_OFF:
@@ -1824,28 +1829,16 @@ static size_t log_output(int facility, int level, enum log_flags lflags, const c
return log_store(facility, level, lflags, 0, dict, dictlen, text, text_len);
}
-asmlinkage int vprintk_emit(int facility, int level,
- const char *dict, size_t dictlen,
- const char *fmt, va_list args)
+/* Must be called under logbuf_lock. */
+int vprintk_store(int facility, int level,
+ const char *dict, size_t dictlen,
+ const char *fmt, va_list args)
{
static char textbuf[LOG_LINE_MAX];
char *text = textbuf;
size_t text_len;
enum log_flags lflags = 0;
- unsigned long flags;
- int printed_len;
- bool in_sched = false;
- if (level == LOGLEVEL_SCHED) {
- level = LOGLEVEL_DEFAULT;
- in_sched = true;
- }
-
- boot_delay_msec(level);
- printk_delay();
-
- /* This stops the holder of console_sem just where we want him */
- logbuf_lock_irqsave(flags);
/*
* The printf needs to come first; we need the syslog
* prefix which might be passed-in as a parameter.
@@ -1886,8 +1879,32 @@ asmlinkage int vprintk_emit(int facility, int level,
if (dict)
lflags |= LOG_PREFIX|LOG_NEWLINE;
- printed_len = log_output(facility, level, lflags, dict, dictlen, text, text_len);
+ if (suppress_message_printing(level))
+ lflags |= LOG_NOCONS;
+
+ return log_output(facility, level, lflags,
+ dict, dictlen, text, text_len);
+}
+
+asmlinkage int vprintk_emit(int facility, int level,
+ const char *dict, size_t dictlen,
+ const char *fmt, va_list args)
+{
+ int printed_len;
+ bool in_sched = false;
+ unsigned long flags;
+
+ if (level == LOGLEVEL_SCHED) {
+ level = LOGLEVEL_DEFAULT;
+ in_sched = true;
+ }
+ boot_delay_msec(level);
+ printk_delay();
+
+ /* This stops the holder of console_sem just where we want him */
+ logbuf_lock_irqsave(flags);
+ printed_len = vprintk_store(facility, level, dict, dictlen, fmt, args);
logbuf_unlock_irqrestore(flags);
/* If called from the scheduler, we can not call up(). */
@@ -2013,7 +2030,6 @@ 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 bool suppress_message_printing(int level) { return false; }
#endif /* CONFIG_PRINTK */
@@ -2349,11 +2365,10 @@ skip:
break;
msg = log_from_idx(console_idx);
- if (suppress_message_printing(msg->level)) {
+ if (msg->flags & LOG_NOCONS) {
/*
- * Skip record we have buffered and already printed
- * directly to the console when we received it, and
- * record that has level above the console loglevel.
+ * Skip record if !ignore_loglevel, and
+ * record has level above the console loglevel.
*/
console_idx = log_next(console_idx);
console_seq++;
@@ -2878,16 +2893,20 @@ void wake_up_klogd(void)
preempt_enable();
}
-int vprintk_deferred(const char *fmt, va_list args)
+void defer_console_output(void)
{
- int r;
-
- r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
-
preempt_disable();
__this_cpu_or(printk_pending, PRINTK_PENDING_OUTPUT);
irq_work_queue(this_cpu_ptr(&wake_up_klogd_work));
preempt_enable();
+}
+
+int vprintk_deferred(const char *fmt, va_list args)
+{
+ int r;
+
+ r = vprintk_emit(0, LOGLEVEL_SCHED, NULL, 0, fmt, args);
+ defer_console_output();
return r;
}
diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index d7d091309054..a0a74c533e4b 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -308,24 +308,33 @@ static __printf(1, 0) int vprintk_nmi(const char *fmt, va_list args)
void printk_nmi_enter(void)
{
- /*
- * The size of the extra per-CPU buffer is limited. Use it only when
- * the main one is locked. If this CPU is not in the safe context,
- * the lock must be taken on another CPU and we could wait for it.
- */
- if ((this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK) &&
- raw_spin_is_locked(&logbuf_lock)) {
- this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
- } else {
- this_cpu_or(printk_context, PRINTK_NMI_DEFERRED_CONTEXT_MASK);
- }
+ this_cpu_or(printk_context, PRINTK_NMI_CONTEXT_MASK);
}
void printk_nmi_exit(void)
{
- this_cpu_and(printk_context,
- ~(PRINTK_NMI_CONTEXT_MASK |
- PRINTK_NMI_DEFERRED_CONTEXT_MASK));
+ this_cpu_and(printk_context, ~PRINTK_NMI_CONTEXT_MASK);
+}
+
+/*
+ * 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 try to store the messages into the main logbuf directly
+ * and use the per-CPU buffers only as a fallback when the lock
+ * is not available.
+ */
+void printk_nmi_direct_enter(void)
+{
+ if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
+ this_cpu_or(printk_context, PRINTK_NMI_DIRECT_CONTEXT_MASK);
+}
+
+void printk_nmi_direct_exit(void)
+{
+ this_cpu_and(printk_context, ~PRINTK_NMI_DIRECT_CONTEXT_MASK);
}
#else
@@ -363,6 +372,20 @@ void __printk_safe_exit(void)
__printf(1, 0) int vprintk_func(const char *fmt, va_list args)
{
+ /*
+ * Try to 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) &&
+ raw_spin_trylock(&logbuf_lock)) {
+ int len;
+
+ len = vprintk_store(0, LOGLEVEL_DEFAULT, NULL, 0, fmt, args);
+ raw_spin_unlock(&logbuf_lock);
+ defer_console_output();
+ return len;
+ }
+
/* Use extra buffer in NMI when logbuf_lock is taken or in safe mode. */
if (this_cpu_read(printk_context) & PRINTK_NMI_CONTEXT_MASK)
return vprintk_nmi(fmt, args);
@@ -371,13 +394,6 @@ __printf(1, 0) int vprintk_func(const char *fmt, va_list args)
if (this_cpu_read(printk_context) & PRINTK_SAFE_CONTEXT_MASK)
return vprintk_safe(fmt, args);
- /*
- * Use the main logbuf when logbuf_lock is available in NMI.
- * But avoid calling console drivers that might have their own locks.
- */
- if (this_cpu_read(printk_context) & PRINTK_NMI_DEFERRED_CONTEXT_MASK)
- return vprintk_deferred(fmt, args);
-
/* No obstacles. */
return vprintk_default(fmt, args);
}
diff --git a/kernel/trace/trace.c b/kernel/trace/trace.c
index 823687997b01..176debd3481b 100644
--- a/kernel/trace/trace.c
+++ b/kernel/trace/trace.c
@@ -8288,6 +8288,7 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
tracing_off();
local_irq_save(flags);
+ printk_nmi_direct_enter();
/* Simulate the iterator */
trace_init_global_iter(&iter);
@@ -8367,7 +8368,8 @@ void ftrace_dump(enum ftrace_dump_mode oops_dump_mode)
for_each_tracing_cpu(cpu) {
atomic_dec(&per_cpu_ptr(iter.trace_buffer->data, cpu)->disabled);
}
- atomic_dec(&dump_running);
+ atomic_dec(&dump_running);
+ printk_nmi_direct_exit();
local_irq_restore(flags);
}
EXPORT_SYMBOL_GPL(ftrace_dump);
generated by cgit v1.2.3 (git 2.39.1) at 2024-12-26 15:47:43 +0000