This patch make sure printing of log on console if loglevel
at time of storing log is less than current console loglevel.
@why
In SMP printk can work asynchronously, logs can be missed on console
because it checks current log level at time of console_unlock,
not at time of storing logs.
func()
{
....
....
console_verbose(); // user wants to have all the logs on console.
pr_alert();
dump_backtrace(); //prints with default loglevel.
...
console_silent(); // stop all logs from printing on console.
}
Now if console_lock was owned by another process, the messages might
be handled after the consoles were silenced.
reused flag LOG_NOCONS as its usage is gone long back.
(5c2992ee7fd8a29d04125dc0aa3522784c5fa5eb)
Signed-off-by: Vaneet Narang <v.nar...@samsung.com>
Signed-off-by: Maninder Singh <maninder...@samsung.com>
---
v1 -> v2: make changes simpler as suggested by Petr Mladek.
use flag rather than changing structure of printk.
kernel/printk/printk.c | 12 +++++++-----
1 file changed, 7 insertions(+), 5 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 2f4af21..4b059fe 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -349,7 +349,7 @@ enum con_msg_format_flags {
*/
enum log_flags {
- LOG_NOCONS = 1, /* already flushed, do not print to console */
+ LOG_NOCONS = 1, /* suppress print, do not print to console */
LOG_NEWLINE = 2, /* text ended with a newline */
LOG_PREFIX = 4, /* text started with a prefix */
LOG_CONT = 8, /* text is a fragment of a continuation line */
@@ -1886,6 +1886,9 @@ asmlinkage int vprintk_emit(int facility, int level,
if (dict)
lflags |= LOG_PREFIX|LOG_NEWLINE;
+ if (suppress_message_printing(level))
+ lflags |= LOG_NOCONS;
+
printed_len = log_output(facility, level, lflags, dict, dictlen, text,
text_len);
logbuf_unlock_irqrestore(flags);
@@ -2355,11 +2358,10 @@ void console_unlock(void)
break;
msg = log_from_idx(console_idx);
- if (suppress_message_printing(msg->level)) {
+ if (msg->flags & LOG_NOCONS) {
/*
- * Skip record we have buffered and already printed
- * directly to the console when we received it, and
- * record that has level above the console loglevel.
+ * Skip record if !ignore_loglevel, and
+ * record has level above the console loglevel.
*/
console_idx = log_next(console_idx);
console_seq++;
--
1.9.1
