[RFC][PATCHv5 4/7] printk: always use deferred printk when flush printk_safe lines

Sergey Senozhatsky
2016-12-01T13:57:54Z

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.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Suggested-by: Petr Mladek <pmladek@suse.com>
---
kernel/printk/printk_safe.c | 12 +++++-------
1 file changed, 5 insertions(+), 7 deletions(-)

diff --git a/kernel/printk/printk_safe.c b/kernel/printk/printk_safe.c
index c22e286..3ded9e1 100644
--- a/kernel/printk/printk_safe.c
+++ b/kernel/printk/printk_safe.c
@@ -100,14 +100,12 @@ static int printk_safe_log_store(struct printk_safe_seq_buf *s,
static 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 */
--
2.10.2