5 files changed, 24 insertions, 4 deletions

diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 52e6fbb042cc..138f6664b2e2 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -3212,6 +3212,7 @@
                         bit 2: print timer info
                         bit 3: print locks info if CONFIG_LOCKDEP is on
                         bit 4: print ftrace buffer
+                        bit 5: print all printk messages in buffer
 
         panic_on_warn   panic() instead of WARN().  Useful to cause kdump
                         on a WARN().
diff --git a/arch/powerpc/kernel/traps.c b/arch/powerpc/kernel/traps.c
index 665f294725cb..83e59fdaa62d 100644
--- a/arch/powerpc/kernel/traps.c
+++ b/arch/powerpc/kernel/traps.c
@@ -179,7 +179,7 @@ extern void panic_flush_kmsg_end(void)
         kmsg_dump(KMSG_DUMP_PANIC);
         bust_spinlocks(0);
         debug_locks_off();
-        console_flush_on_panic();
+        console_flush_on_panic(CONSOLE_FLUSH_PENDING);
 }
 
 static unsigned long oops_begin(struct pt_regs *regs)
diff --git a/include/linux/console.h b/include/linux/console.h
index ec9bdb3d7bab..d09951d5a94e 100644
--- a/include/linux/console.h
+++ b/include/linux/console.h
@@ -166,6 +166,11 @@ struct console {
 extern int console_set_on_cmdline;
 extern struct console *early_console;
 
+enum con_flush_mode {
+        CONSOLE_FLUSH_PENDING,
+        CONSOLE_REPLAY_ALL,
+};
+
 extern int add_preferred_console(char *name, int idx, char *options);
 extern void register_console(struct console *);
 extern int unregister_console(struct console *);
@@ -175,7 +180,7 @@ extern int console_trylock(void);
 extern void console_unlock(void);
 extern void console_conditional_schedule(void);
 extern void console_unblank(void);
-extern void console_flush_on_panic(void);
+extern void console_flush_on_panic(enum con_flush_mode mode);
 extern struct tty_driver *console_device(int *);
 extern void console_stop(struct console *);
 extern void console_start(struct console *);
diff --git a/kernel/panic.c b/kernel/panic.c
index 8779d64bace0..b4543a31a495 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -51,6 +51,7 @@ EXPORT_SYMBOL_GPL(panic_timeout);
 #define PANIC_PRINT_TIMER_INFO          0x00000004
 #define PANIC_PRINT_LOCK_INFO           0x00000008
 #define PANIC_PRINT_FTRACE_INFO         0x00000010
+#define PANIC_PRINT_ALL_PRINTK_MSG      0x00000020
 unsigned long panic_print;
 
 ATOMIC_NOTIFIER_HEAD(panic_notifier_list);
@@ -134,6 +135,9 @@ EXPORT_SYMBOL(nmi_panic);
 
 static void panic_print_sys_info(void)
 {
+        if (panic_print & PANIC_PRINT_ALL_PRINTK_MSG)
+                console_flush_on_panic(CONSOLE_REPLAY_ALL);
+
         if (panic_print & PANIC_PRINT_TASK_INFO)
                 show_state();
 
@@ -277,7 +281,7 @@ void panic(const char *fmt, ...)
          * panic() is not being callled from OOPS.
          */
         debug_locks_off();
-        console_flush_on_panic();
+        console_flush_on_panic(CONSOLE_FLUSH_PENDING);
 
         panic_print_sys_info();
 
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 17102fd4c136..a6e06fe38e41 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2535,10 +2535,11 @@ void console_unblank(void)
 
 /**
  * console_flush_on_panic - flush console content on panic
+ * @mode: flush all messages in buffer or just the pending ones
  *
  * Immediately output all pending messages no matter what.
  */
-void console_flush_on_panic(void)
+void console_flush_on_panic(enum con_flush_mode mode)
 {
         /*
          * If someone else is holding the console lock, trylock will fail
@@ -2549,6 +2550,15 @@ void console_flush_on_panic(void)
          */
         console_trylock();
         console_may_schedule = 0;
+
+        if (mode == CONSOLE_REPLAY_ALL) {
+                unsigned long flags;
+
+                logbuf_lock_irqsave(flags);
+                console_seq = log_first_seq;
+                console_idx = log_first_idx;
+                logbuf_unlock_irqrestore(flags);
+        }
         console_unlock();
 }