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: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>

1 files changed, 0 insertions, 291 deletions

diff --git a/kernel/printk/nmi.c b/kernel/printk/nmi.c
deleted file mode 100644
index f011aaef583c..000000000000
--- a/kernel/printk/nmi.c
+++ /dev/null
@@ -1,291 +0,0 @@
-/*
- * nmi.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
- * as published by the Free Software Foundation; either version 2
- * of the License, or (at your option) any later version.
- *
- * This program is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
- * GNU General Public License for more details.
- *
- * You should have received a copy of the GNU General Public License
- * along with this program; if not, see <http://www.gnu.org/licenses/>.
- */
-
-#include <linux/preempt.h>
-#include <linux/spinlock.h>
-#include <linux/debug_locks.h>
-#include <linux/smp.h>
-#include <linux/cpumask.h>
-#include <linux/irq_work.h>
-#include <linux/printk.h>
-
-#include "internal.h"
-
-/*
- * printk() could not take logbuf_lock in NMI context. 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
- * via @printk_func 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_PER_CPU(printk_func_t, printk_func) = vprintk_default;
-static int printk_nmi_irq_ready;
-atomic_t nmi_message_lost;
-
-#define NMI_LOG_BUF_LEN ((1 << CONFIG_NMI_LOG_BUF_SHIFT) -		\
-			 sizeof(atomic_t) - sizeof(struct irq_work))
-
-struct nmi_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];
-};
-static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
-
-/*
- * 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 int vprintk_nmi(const char *fmt, va_list args)
-{
-	struct nmi_seq_buf *s = this_cpu_ptr(&nmi_print_seq);
-	int add = 0;
-	size_t len;
-
-again:
-	len = atomic_read(&s->len);
-
-	/* The trailing '\0' is not counted into len. */
-	if (len >= sizeof(s->buffer) - 1) {
-		atomic_inc(&nmi_message_lost);
-		return 0;
-	}
-
-	/*
-	 * Make sure that all old data have been read before the buffer was
-	 * reseted. This is not needed when we just append data.
-	 */
-	if (!len)
-		smp_rmb();
-
-	add = vscnprintf(s->buffer + len, sizeof(s->buffer) - len, fmt, args);
-
-	/*
-	 * 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;
-
-	/* Get flushed in a more safe context. */
-	if (add && printk_nmi_irq_ready) {
-		/* Make sure that IRQ work is really initialized. */
-		smp_rmb();
-		irq_work_queue(&s->work);
-	}
-
-	return add;
-}
-
-static void printk_nmi_flush_line(const char *text, int len)
-{
-	/*
-	 * The buffers are flushed in NMI only on 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.
-	 */
-	if (in_nmi())
-		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)
-{
-	const char *c, *end;
-	bool header;
-
-	c = start;
-	end = start + len;
-	header = true;
-
-	/* Print line by line. */
-	while (c < end) {
-		if (*c == '\n') {
-			printk_nmi_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_nmi_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_nmi_flush_line(start, end - start);
-		printk_nmi_flush_line(newline, strlen(newline));
-	}
-
-	return 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 raw_spinlock_t read_lock =
-		__RAW_SPIN_LOCK_INITIALIZER(read_lock);
-	struct nmi_seq_buf *s = container_of(work, struct nmi_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(&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_nmi_flush: internal error\n";
-
-		printk_nmi_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_nmi_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:
-	raw_spin_unlock_irqrestore(&read_lock, flags);
-}
-
-/**
- * printk_nmi_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)
-{
-	int cpu;
-
-	for_each_possible_cpu(cpu)
-		__printk_nmi_flush(&per_cpu(nmi_print_seq, cpu).work);
-}
-
-/**
- * printk_nmi_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
- * 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)
-{
-	/*
-	 * Make sure that we could access the main ring buffer.
-	 * Do not risk a double release when more CPUs are up.
-	 */
-	if (in_nmi() && raw_spin_is_locked(&logbuf_lock)) {
-		if (num_online_cpus() > 1)
-			return;
-
-		debug_locks_off();
-		raw_spin_lock_init(&logbuf_lock);
-	}
-
-	printk_nmi_flush();
-}
-
-void __init printk_nmi_init(void)
-{
-	int cpu;
-
-	for_each_possible_cpu(cpu) {
-		struct nmi_seq_buf *s = &per_cpu(nmi_print_seq, cpu);
-
-		init_irq_work(&s->work, __printk_nmi_flush);
-	}
-
-	/* Make sure that IRQ works are initialized before enabling. */
-	smp_wmb();
-	printk_nmi_irq_ready = 1;
-
-	/* Flush pending messages that did not have scheduled IRQ works. */
-	printk_nmi_flush();
-}
-
-void printk_nmi_enter(void)
-{
-	this_cpu_write(printk_func, vprintk_nmi);
-}
-
-void printk_nmi_exit(void)
-{
-	this_cpu_write(printk_func, vprintk_default);
-}