Commit f92bac3b authored by Sergey Senozhatsky's avatar Sergey Senozhatsky Committed by Petr Mladek

printk: rename nmi.c and exported api

A preparation patch for printk_safe work. No functional change.
- rename nmi.c to print_safe.c
- add `printk_safe' prefix to some (which used both by printk-safe
  and printk-nmi) of the exported functions.

Link: http://lkml.kernel.org/r/20161227141611.940-3-sergey.senozhatsky@gmail.com
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Calvin Owens <calvinowens@fb.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Peter Hurley <peter@hurleysoftware.com>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: default avatarSergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: default avatarPetr Mladek <pmladek@suse.com>
parent bd66a892
......@@ -147,17 +147,17 @@ void early_printk(const char *s, ...) { }
#endif
#ifdef CONFIG_PRINTK_NMI
extern void printk_nmi_init(void);
extern void printk_safe_init(void);
extern void printk_nmi_enter(void);
extern void printk_nmi_exit(void);
extern void printk_nmi_flush(void);
extern void printk_nmi_flush_on_panic(void);
extern void printk_safe_flush(void);
extern void printk_safe_flush_on_panic(void);
#else
static inline void printk_nmi_init(void) { }
static inline void printk_safe_init(void) { }
static inline void printk_nmi_enter(void) { }
static inline void printk_nmi_exit(void) { }
static inline void printk_nmi_flush(void) { }
static inline void printk_nmi_flush_on_panic(void) { }
static inline void printk_safe_flush(void) { }
static inline void printk_safe_flush_on_panic(void) { }
#endif /* PRINTK_NMI */
#ifdef CONFIG_PRINTK
......
......@@ -875,17 +875,19 @@ config LOG_CPU_MAX_BUF_SHIFT
13 => 8 KB for each CPU
12 => 4 KB for each CPU
config NMI_LOG_BUF_SHIFT
int "Temporary per-CPU NMI log buffer size (12 => 4KB, 13 => 8KB)"
config PRINTK_SAFE_LOG_BUF_SHIFT
int "Temporary per-CPU printk log buffer size (12 => 4KB, 13 => 8KB)"
range 10 21
default 13
depends on PRINTK_NMI
depends on PRINTK
help
Select the size of a per-CPU buffer where NMI messages are temporary
stored. They are copied to the main log buffer in a safe context
to avoid a deadlock. The value defines the size as a power of 2.
Select the size of an alternate printk per-CPU buffer where messages
printed from usafe contexts are temporary stored. One example would
be NMI messages, another one - printk recursion. The messages are
copied to the main log buffer in a safe context to avoid a deadlock.
The value defines the size as a power of 2.
NMI messages are rare and limited. The largest one is when
Those messages are rare and limited. The largest one is when
a backtrace is printed. It usually fits into 4KB. Select
8KB if you want to be on the safe side.
......
......@@ -580,7 +580,7 @@ asmlinkage __visible void __init start_kernel(void)
timekeeping_init();
time_init();
sched_clock_postinit();
printk_nmi_init();
printk_safe_init();
perf_event_init();
profile_init();
call_function_init();
......
......@@ -916,7 +916,7 @@ void crash_kexec(struct pt_regs *regs)
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_nmi_flush_on_panic();
printk_safe_flush_on_panic();
__crash_kexec(regs);
/*
......
......@@ -188,7 +188,7 @@ void panic(const char *fmt, ...)
* Bypass the panic_cpu check and call __crash_kexec directly.
*/
if (!_crash_kexec_post_notifiers) {
printk_nmi_flush_on_panic();
printk_safe_flush_on_panic();
__crash_kexec(NULL);
/*
......@@ -213,7 +213,7 @@ void panic(const char *fmt, ...)
atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
/* Call flush even twice. It tries harder with a single online CPU */
printk_nmi_flush_on_panic();
printk_safe_flush_on_panic();
kmsg_dump(KMSG_DUMP_PANIC);
/*
......
obj-y = printk.o
obj-$(CONFIG_PRINTK_NMI) += nmi.o
obj-$(CONFIG_PRINTK_NMI) += printk_safe.o
obj-$(CONFIG_A11Y_BRAILLE_CONSOLE) += braille.o
/*
* nmi.c - Safe printk in NMI context
* printk_safe.c - Safe printk in NMI context
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
......@@ -39,18 +39,18 @@
* were handled or when IRQs are blocked.
*/
DEFINE_PER_CPU(printk_func_t, printk_func) = vprintk_default;
static int printk_nmi_irq_ready;
static int printk_safe_irq_ready;
atomic_t nmi_message_lost;
#define NMI_LOG_BUF_LEN ((1 << CONFIG_NMI_LOG_BUF_SHIFT) - \
#define SAFE_LOG_BUF_LEN ((1 << CONFIG_PRINTK_SAFE_LOG_BUF_SHIFT) - \
sizeof(atomic_t) - sizeof(struct irq_work))
struct nmi_seq_buf {
struct printk_safe_seq_buf {
atomic_t len; /* length of written data */
struct irq_work work; /* IRQ work that flushes the buffer */
unsigned char buffer[NMI_LOG_BUF_LEN];
unsigned char buffer[SAFE_LOG_BUF_LEN];
};
static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
static DEFINE_PER_CPU(struct printk_safe_seq_buf, nmi_print_seq);
/*
* Safe printk() for NMI context. It uses a per-CPU buffer to
......@@ -60,7 +60,7 @@ static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
*/
static int vprintk_nmi(const char *fmt, va_list args)
{
struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
struct printk_safe_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
int add = 0;
size_t len;
......@@ -91,7 +91,7 @@ static int vprintk_nmi(const char *fmt, va_list args)
goto again;
/* Get flushed in a more safe context. */
if (add && printk_nmi_irq_ready) {
if (add && printk_safe_irq_ready) {
/* Make sure that IRQ work is really initialized. */
smp_rmb();
irq_work_queue(&s->work);
......@@ -100,7 +100,7 @@ static int vprintk_nmi(const char *fmt, va_list args)
return add;
}
static void printk_nmi_flush_line(const char *text, int len)
static void printk_safe_flush_line(const char *text, int len)
{
/*
* The buffers are flushed in NMI only on panic. The messages must
......@@ -111,11 +111,10 @@ static void printk_nmi_flush_line(const char *text, int len)
printk_deferred("%.*s", len, text);
else
printk("%.*s", len, text);
}
/* printk part of the temporary buffer line by line */
static int printk_nmi_flush_buffer(const char *start, size_t len)
static int printk_safe_flush_buffer(const char *start, size_t len)
{
const char *c, *end;
bool header;
......@@ -127,7 +126,7 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
/* Print line by line. */
while (c < end) {
if (*c == '\n') {
printk_nmi_flush_line(start, c - start + 1);
printk_safe_flush_line(start, c - start + 1);
start = ++c;
header = true;
continue;
......@@ -140,7 +139,7 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
continue;
}
printk_nmi_flush_line(start, c - start);
printk_safe_flush_line(start, c - start);
start = c++;
header = true;
continue;
......@@ -154,8 +153,8 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
if (start < end && !header) {
static const char newline[] = KERN_CONT "\n";
printk_nmi_flush_line(start, end - start);
printk_nmi_flush_line(newline, strlen(newline));
printk_safe_flush_line(start, end - start);
printk_safe_flush_line(newline, strlen(newline));
}
return len;
......@@ -165,11 +164,12 @@ static int printk_nmi_flush_buffer(const char *start, size_t len)
* Flush data from the associated per_CPU buffer. The function
* can be called either via IRQ work or independently.
*/
static void __printk_nmi_flush(struct irq_work *work)
static void __printk_safe_flush(struct irq_work *work)
{
static raw_spinlock_t read_lock =
__RAW_SPIN_LOCK_INITIALIZER(read_lock);
struct nmi_seq_buf *s = container_of(work, struct nmi_seq_buf, work);
struct printk_safe_seq_buf *s =
container_of(work, struct printk_safe_seq_buf, work);
unsigned long flags;
size_t len;
int i;
......@@ -194,9 +194,9 @@ static void __printk_nmi_flush(struct irq_work *work)
* buffer size.
*/
if ((i && i >= len) || len > sizeof(s->buffer)) {
const char *msg = "printk_nmi_flush: internal error\n";
const char *msg = "printk_safe_flush: internal error\n";
printk_nmi_flush_line(msg, strlen(msg));
printk_safe_flush_line(msg, strlen(msg));
len = 0;
}
......@@ -205,7 +205,7 @@ static void __printk_nmi_flush(struct irq_work *work)
/* Make sure that data has been written up to the @len */
smp_rmb();
i += printk_nmi_flush_buffer(s->buffer + i, len - i);
i += printk_safe_flush_buffer(s->buffer + i, len - i);
/*
* Check that nothing has got added in the meantime and truncate
......@@ -221,31 +221,31 @@ static void __printk_nmi_flush(struct irq_work *work)
}
/**
* printk_nmi_flush - flush all per-cpu nmi buffers.
* 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_nmi_flush(void)
void printk_safe_flush(void)
{
int cpu;
for_each_possible_cpu(cpu)
__printk_nmi_flush(&per_cpu(nmi_print_seq, cpu).work);
__printk_safe_flush(&per_cpu(nmi_print_seq, cpu).work);
}
/**
* printk_nmi_flush_on_panic - flush all per-cpu nmi buffers when the system
* printk_safe_flush_on_panic - flush all per-cpu nmi buffers when the system
* goes down.
*
* Similar to printk_nmi_flush() but it can be called even in NMI context when
* 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_nmi_flush_on_panic(void)
void printk_safe_flush_on_panic(void)
{
/*
* Make sure that we could access the main ring buffer.
......@@ -259,25 +259,25 @@ void printk_nmi_flush_on_panic(void)
raw_spin_lock_init(&logbuf_lock);
}
printk_nmi_flush();
printk_safe_flush();
}
void __init printk_nmi_init(void)
void __init printk_safe_init(void)
{
int cpu;
for_each_possible_cpu(cpu) {
struct nmi_seq_buf *s = &per_cpu(nmi_print_seq, cpu);
struct printk_safe_seq_buf *s = &per_cpu(nmi_print_seq, cpu);
init_irq_work(&s->work, __printk_nmi_flush);
init_irq_work(&s->work, __printk_safe_flush);
}
/* Make sure that IRQ works are initialized before enabling. */
smp_wmb();
printk_nmi_irq_ready = 1;
printk_safe_irq_ready = 1;
/* Flush pending messages that did not have scheduled IRQ works. */
printk_nmi_flush();
printk_safe_flush();
}
void printk_nmi_enter(void)
......
......@@ -77,7 +77,7 @@ void nmi_trigger_cpumask_backtrace(const cpumask_t *mask,
* Force flush any remote buffers that might be stuck in IRQ context
* and therefore could not run their irq_work.
*/
printk_nmi_flush();
printk_safe_flush();
clear_bit_unlock(0, &backtrace_flag);
put_cpu();
......
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