Messages in this thread Patch in this message | | | From | John Ogness <> | Subject | [PATCH printk] printk: flush consoles before checking progress | Date | Fri, 29 Sep 2023 13:38:33 +0206 |
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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.
Finally, in case pr_flush() needs to poll-wait (for example, because there has been a handover to another CPU), reduce the polling interval from 100ms to 1ms. In the bug report it was mentioned that 100ms is unnecessarily long.
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") Signed-off-by: John Ogness <john.ogness@linutronix.de> --- kernel/printk/printk.c | 23 ++++++++++++----------- 1 file changed, 12 insertions(+), 11 deletions(-)
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c index 7e0b4dd02398..cf7841fc6eef 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(); @@ -3775,16 +3781,11 @@ static bool __pr_flush(struct console *con, int timeout_ms, bool reset_on_progre if (diff == 0 || remaining == 0) break; - if (remaining < 0) { - /* no timeout limit */ - msleep(100); - } else if (remaining < 100) { - msleep(remaining); - remaining = 0; - } else { - msleep(100); - remaining -= 100; - } + msleep(1); + + /* If @remaining < 0, there is no timeout limit. */ + if (remaining > 0) + remaining--; last_diff = diff; } base-commit: 4952801fc6adb5b50b8ec2bcc5aeef92fcce8730 -- 2.39.2
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