From: John Ogness <[email protected]>
Commit 9e70a5e109a4 ("printk: Add per-console suspended state")
removed console lock usage during resume and replaced it with
the clearly defined console_list_lock and srcu mechanisms.
However, the console lock usage had an important side-effect
of flushing the consoles. After its removal, consoles were no
longer flushed before checking their progress.
Add the console_lock/console_unlock dance to the beginning
of __pr_flush() to actually flush the consoles before checking
their progress. Also add comments to clarify this additional
usage of the console lock.
Note that console_unlock() does not guarantee flushing all messages
since the commit dbdda842fe96f89 ("printk: Add console owner and waiter
logic to load balance console writes").
Reported-by: Todd Brandt <[email protected]>
Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217955
Fixes: 9e70a5e109a4 ("printk: Add per-console suspended state")
Co-developed-by: Petr Mladek <[email protected]>
Signed-off-by: Petr Mladek <[email protected]>
Signed-off-by: John Ogness <[email protected]>
---
kernel/printk/printk.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
index 7e0b4dd02398..0b3af1529778 100644
--- a/kernel/printk/printk.c
+++ b/kernel/printk/printk.c
@@ -3740,12 +3740,18 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
seq = prb_next_seq(prb);
+ /* Flush the consoles so that records up to @seq are printed. */
+ console_lock();
+ console_unlock();
+
for (;;) {
diff = 0;
/*
* Hold the console_lock to guarantee safe access to
- * console->seq.
+ * console->seq. Releasing console_lock flushes more
+ * records in case @seq is still not printed on all
+ * usable consoles.
*/
console_lock();
--
2.35.3