8 files changed, 53 insertions, 51 deletions

diff --git a/include/linux/printk.h b/include/linux/printk.h
index 3472cc6b7a60..37e933eeffb2 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_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
diff --git a/init/Kconfig b/init/Kconfig
index 223b734abccd..760b7d0bc9d7 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -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.
 
diff --git a/init/main.c b/init/main.c
index b0c9d6facef9..b4ca17d9bdeb 100644
--- a/init/main.c
+++ b/init/main.c
@@ -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();
diff --git a/kernel/kexec_core.c b/kernel/kexec_core.c
index 5617cc412444..14bb9eb76665 100644
--- a/kernel/kexec_core.c
+++ b/kernel/kexec_core.c
@@ -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);
 
                 /*
diff --git a/kernel/panic.c b/kernel/panic.c
index c51edaa04fce..8c8efcd310e7 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 abb0042a427b..607928119f26 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
index f011aaef583c..fc80359dcd78 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
@@ -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 @@ again:
                 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 @@ again:
         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 @@ more:
          * 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 @@ more:
 
         /* 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 @@ out:
 }
 
 /**
- * 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)
diff --git a/lib/nmi_backtrace.c b/lib/nmi_backtrace.c
index 75554754eadf..5f7999eacad5 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();