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Subject[PATCH 2/2] printk: always report lost messages on serial console
Date
The "printk messages dropped" report is 'attached' to a kernel
message located at console_idx offset. This does not work well
if we skip that message due to loglevel filtering, because in
this case we also skip/lose dropped message report.

Disable suppress_message_printing() loglevel filtering if we
must report "printk messages dropped" condition.

Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
---
kernel/printk/printk.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 11a9842a2f47..6a7ebcb0bb6e 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -2218,6 +2218,7 @@ void console_unlock(void)
struct printk_log *msg;
size_t ext_len = 0;
size_t len;
+ bool report_dropped_msg = false;

raw_spin_lock_irqsave(&logbuf_lock, flags);
if (seen_seq != log_next_seq) {
@@ -2232,6 +2233,7 @@ void console_unlock(void)
/* messages are gone, move to first one */
console_seq = log_first_seq;
console_idx = log_first_idx;
+ report_dropped_msg = true;
} else {
len = 0;
}
@@ -2240,7 +2242,8 @@ void console_unlock(void)
break;

msg = log_from_idx(console_idx);
- if (suppress_message_printing(msg->level)) {
+ if (!report_dropped_msg &&
+ suppress_message_printing(msg->level)) {
/*
* Skip record we have buffered and already printed
* directly to the console when we received it, and
--
2.11.0
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