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authorJohn Ogness <john.ogness@linutronix.de>2023-10-06 10:21:50 +0200
committerPetr Mladek <pmladek@suse.com>2023-10-09 10:15:04 +0200
commit054c22bd784d6953ac85f545bed4a2a27b0e4ddb (patch)
treedcf80e1082fa0ec75f52a245ae0609a89ca1d033 /kernel/printk
parent132a90d1527fedba2d95085c951ccf00dbbebe41 (diff)
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 <todd.e.brandt@intel.com> Closes: https://bugzilla.kernel.org/show_bug.cgi?id=217955 Fixes: 9e70a5e109a4 ("printk: Add per-console suspended state") Co-developed-by: Petr Mladek <pmladek@suse.com> Signed-off-by: Petr Mladek <pmladek@suse.com> Signed-off-by: John Ogness <john.ogness@linutronix.de> Link: https://lore.kernel.org/r/20231006082151.6969-2-pmladek@suse.com
Diffstat (limited to 'kernel/printk')
-rw-r--r--kernel/printk/printk.c8
1 files changed, 7 insertions, 1 deletions
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();