On Wed, May 22, 2024 at 05:18:13PM +0200, Petr Mladek wrote: > > On Wed 2024-03-13 15:50:52, Sreenath Vijayan wrote: > > Add a generic function console_replay_all() for replaying > > the kernel log on consoles, in any context. It would allow > > viewing the logs on an unresponsive terminal via sysrq. > > > > Reuse the existing code from console_flush_on_panic() for > > resetting the sequence numbers, by introducing a new helper > > function __console_rewind_all(). It is safe to be called > > under console_lock(). > > > > Try to acquire lock on the console subsystem without waiting. > > If successful, reset the sequence number to oldest available > > record on all consoles and call console_unlock() which will > > automatically flush the messages to the consoles. > > > > --- a/kernel/printk/printk.c > > +++ b/kernel/printk/printk.c > > @@ -4259,6 +4271,23 @@ void kmsg_dump_rewind(struct kmsg_dump_iter *iter) > > } > > EXPORT_SYMBOL_GPL(kmsg_dump_rewind); > > > > +/** > > + * console_replay_all - replay kernel log on consoles > > It should rather be called "console_try_replay_all()" to make it clear > that it is just the best effort. > Ok, noted. > > + * > > + * Try to obtain lock on console subsystem and replay all > > + * available records in printk buffer on the consoles. > > + * Does nothing if lock is not obtained. > > + * > > + * Context: Any context. > > This should be: > > * Context: Any, except for NMI > > Basically only lockless code is safe in NMI which is not the case here. > Understood. > > + */ > > +void console_replay_all(void) > > +{ > > + if (console_trylock()) { > > + __console_rewind_all(); > > + /* Consoles are flushed as part of console_unlock(). */ > > + console_unlock(); > > + } > > +} > > #endif > > Otherwise, it looks good. With the two changes: > > Reviewed-by: Petr Mladek <pmladek@xxxxxxxx> > > I am sorry for the late review. I have been snowed under tasks. > Also I had healthy problems. > > I have seen a mail that Greg has queued the patch in tty-next. > I am not sure if it still can be fixed. It will be perfectly fine > to change this by a followup patch. > > Best Regards, > Petr Thank you for the review comments. As the patch has been merged to mainline, I will soon send a followup patch with "Fixes:" tag. Regards, Sreenath