A preparation patch for printk_safe work. No functional change.
- rename nmi.c to print_safe.c
- rename exported functions to have a `printk_safe' prefix.

Signed-off-by: Sergey Senozhatsky <sergey.senozhat...@gmail.com>
Acked-by: Steven Rostedt <rost...@goodmis.org>
Reviewed-by: Petr Mladek <pmla...@suse.com>
---
 arch/arm/kernel/smp.c                  |  4 +-
 include/linux/hardirq.h                |  4 +-
 include/linux/printk.h                 | 20 +++++-----
 init/Kconfig                           | 16 ++++----
 init/main.c                            |  2 +-
 kernel/kexec_core.c                    |  2 +-
 kernel/panic.c                         |  4 +-
 kernel/printk/Makefile                 |  2 +-
 kernel/printk/{nmi.c => printk_safe.c} | 72 +++++++++++++++++-----------------
 lib/nmi_backtrace.c                    |  2 +-
 10 files changed, 65 insertions(+), 63 deletions(-)
 rename kernel/printk/{nmi.c => printk_safe.c} (77%)

diff --git a/arch/arm/kernel/smp.c b/arch/arm/kernel/smp.c
index 7dd14e8..8b056e1 100644
--- a/arch/arm/kernel/smp.c
+++ b/arch/arm/kernel/smp.c
@@ -644,11 +644,11 @@ void handle_IPI(int ipinr, struct pt_regs *regs)
                break;
 
        case IPI_CPU_BACKTRACE:
-               printk_nmi_enter();
+               printk_safe_nmi_enter();
                irq_enter();
                nmi_cpu_backtrace(regs);
                irq_exit();
-               printk_nmi_exit();
+               printk_safe_nmi_exit();
                break;
 
        default:
diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h
index c683996..14840aa 100644
--- a/include/linux/hardirq.h
+++ b/include/linux/hardirq.h
@@ -61,7 +61,7 @@ extern void irq_exit(void);
 
 #define nmi_enter()                                            \
        do {                                                    \
-               printk_nmi_enter();                             \
+               printk_safe_nmi_enter();                        \
                lockdep_off();                                  \
                ftrace_nmi_enter();                             \
                BUG_ON(in_nmi());                               \
@@ -78,7 +78,7 @@ extern void irq_exit(void);
                preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \
                ftrace_nmi_exit();                              \
                lockdep_on();                                   \
-               printk_nmi_exit();                              \
+               printk_safe_nmi_exit();                         \
        } while (0)
 
 #endif /* LINUX_HARDIRQ_H */
diff --git a/include/linux/printk.h b/include/linux/printk.h
index 3472cc6..67df41e 100644
--- a/include/linux/printk.h
+++ b/include/linux/printk.h
@@ -147,17 +147,17 @@ void early_printk(const char *s, ...) { }
 #endif
 
 #ifdef CONFIG_PRINTK_NMI
-extern void printk_nmi_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_init(void);
+extern void printk_safe_nmi_enter(void);
+extern void printk_safe_nmi_exit(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_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_init(void) { }
+static inline void printk_safe_nmi_enter(void) { }
+static inline void printk_safe_nmi_exit(void) { }
+static inline void printk_safe_flush(void) { }
+static inline void printk_safe_flush_on_panic(void) { }
 #endif /* PRINTK_NMI */
 
 #ifdef CONFIG_PRINTK
diff --git a/init/Kconfig b/init/Kconfig
index 271692a..0662a43 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -862,17 +862,19 @@ 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.
 
diff --git a/init/main.c b/init/main.c
index 74cf81e..8e4e337 100644
--- a/init/main.c
+++ b/init/main.c
@@ -578,7 +578,7 @@ 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();
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 8ad3a29e..344cd78 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -914,7 +914,7 @@ 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);
 
                /*
diff --git a/kernel/panic.c b/kernel/panic.c
index c51edaa..8c8efcd 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -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);
 
        /*
diff --git a/kernel/printk/Makefile b/kernel/printk/Makefile
index abb0042..6079281 100644
--- a/kernel/printk/Makefile
+++ b/kernel/printk/Makefile
@@ -1,3 +1,3 @@
 obj-y  = printk.o
-obj-$(CONFIG_PRINTK_NMI)               += nmi.o
+obj-$(CONFIG_PRINTK_NMI)               += printk_safe.o
 obj-$(CONFIG_A11Y_BRAILLE_CONSOLE)     += braille.o
diff --git a/kernel/printk/nmi.c b/kernel/printk/printk_safe.c
similarity index 77%
rename from kernel/printk/nmi.c
rename to kernel/printk/printk_safe.c
index 26cd42d..d5a4b6f 100644
--- a/kernel/printk/nmi.c
+++ b/kernel/printk/printk_safe.c
@@ -1,5 +1,5 @@
 /*
- * 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
@@ -58,9 +58,9 @@ static DEFINE_PER_CPU(struct nmi_seq_buf, nmi_print_seq);
  * 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)
+static int vprintk_safe_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;
 
@@ -90,7 +90,7 @@ 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);
@@ -99,7 +99,7 @@ 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
@@ -110,11 +110,10 @@ 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;
@@ -126,7 +125,7 @@ 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;
@@ -139,7 +138,7 @@ 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;
@@ -153,8 +152,8 @@ 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;
@@ -164,11 +163,12 @@ 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;
@@ -193,9 +193,9 @@ 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;
        }
 
@@ -204,7 +204,7 @@ 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
@@ -220,31 +220,31 @@ 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.
@@ -258,33 +258,33 @@ 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)
+void printk_safe_nmi_enter(void)
 {
-       this_cpu_write(printk_func, vprintk_nmi);
+       this_cpu_write(printk_func, vprintk_safe_nmi);
 }
 
-void printk_nmi_exit(void)
+void printk_safe_nmi_exit(void)
 {
        this_cpu_write(printk_func, vprintk_default);
 }
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 7555475..5f7999e 100644
--- a/lib/nmi_backtrace.c
+++ b/lib/nmi_backtrace.c
@@ -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();
-- 
2.10.2

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