From 054c22bd784d6953ac85f545bed4a2a27b0e4ddb Mon Sep 17 00:00:00 2001 From: John Ogness Date: Fri, 6 Oct 2023 10:21:50 +0200 Subject: printk: flush consoles before checking progress 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 Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217955 Fixes: 9e70a5e109a4 ("printk: Add per-console suspended state") Co-developed-by: Petr Mladek Signed-off-by: Petr Mladek Signed-off-by: John Ogness Link: https://lore.kernel.org/r/20231006082151.6969-2-pmladek@suse.com --- kernel/printk/printk.c | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) (limited to 'kernel/printk') diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 8787d3a72114..1919899b6897 100644 --- a/kernel/printk/printk.c +++ b/kernel/printk/printk.c @@ -3738,12 +3738,18 @@ 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(); -- cgit v1.2.3