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printk: do not wait for consoles when suspended 

The console_stop() and console_start() functions call pr_flush().
When suspending, these functions are called by the serial subsystem
while the serial port is suspended. In this scenario, if there are
any pending messages, a call to pr_flush() will always result in a
timeout because the serial port cannot make forward progress. This
causes longer suspend and resume times.

Add a check in pr_flush() so that it will immediately timeout if
the consoles are suspended.

Fixes: 3b604ca812 ("printk: add pr_flush()")
Reported-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: John Ogness <john.ogness@linutronix.de>
Tested-by: Todd Brandt <todd.e.brandt@linux.intel.com>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Link: https://lore.kernel.org/r/20220715061042.373640-2-john.ogness@linutronix.de
This commit is contained in:
John Ogness 2022-07-15 08:16:42 +02:06 committed by Petr Mladek
parent 07a22b6194
commit 9023ca0866
1 changed files with 11 additions and 2 deletions
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13
kernel/printk/printk.c
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@ -3380,6 +3380,7 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
diff = 0;
console_lock();
for_each_console(c) {
if (con && con != c)
continue;
@ -3389,11 +3390,19 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre
if (printk_seq < seq)
diff += seq - printk_seq;
}
console_unlock();
if (diff != last_diff && reset_on_progress)
/*
* If consoles are suspended, it cannot be expected that they
* make forward progress, so timeout immediately. @diff is
* still used to return a valid flush status.
*/
if (console_suspended)
remaining = 0;
else if (diff != last_diff && reset_on_progress)
remaining = timeout_ms;
console_unlock();
if (diff == 0 || remaining == 0)
break;