printk: always use deferred printk when flush printk_safe lines

Always use printk_deferred() in printk_safe_flush_line().
Flushing can be done from NMI or printk_safe contexts (when
we are in panic), so we can't call console drivers, yet still
want to store the messages in the logbuf buffer. Therefore we
use a deferred printk version.

Link: http://lkml.kernel.org/r/[email protected]
Cc: Andrew Morton <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Jan Kara <[email protected]>
Cc: Tejun Heo <[email protected]>
Cc: Calvin Owens <[email protected]>
Cc: Ingo Molnar <[email protected]>
Cc: Peter Zijlstra <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Cc: Peter Hurley <[email protected]>
Cc: [email protected]
Signed-off-by: Sergey Senozhatsky <[email protected]>
Suggested-by: Petr Mladek <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>
Reviewed-by: Steven Rostedt (VMware) <[email protected]>

1 files changed, 6 insertions, 8 deletions

diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index efc89a4e9df5..5214d326d3ba 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -110,17 +110,15 @@ again:
 	return add;
 }
 
-static void printk_safe_flush_line(const char *text, int len)
+static inline void printk_safe_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.
+	 * Avoid any console drivers calls from here, because we may be
+	 * in NMI or printk_safe context (when in 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_deferred("%.*s", len, text);
 }
 
 /* printk part of the temporary buffer line by line */