Re: [PATCH] printk: kmsg_dump: revert msg_print_text() workaround

From: Petr Mladek
Date: Thu Jan 14 2021 - 10:50:55 EST


On Thu 2021-01-14 10:11:11, John Ogness wrote:
> The old msg_print_text() function only filled up to size-1 bytes of
> the buffer. A workaround for this quirky behavior was implemented
> with commit c9dccacfccc7 ("printk: Do not lose last line in kmsg
> buffer dump").
>
> However, with commit 896fbe20b4e2 ("printk: use the lockless
> ringbuffer"), msg_print_text() was replaced by,
> which will fill the full buffer. Therefore, the workaround is now
> incorrectly assuming less data can fit into the buffer. Revert the
> workaround.

We should make record_print_text() behave the same as msg_print_text()
behaved. There might be more users affected by this change and even
in userspace :-(

Let's discuss it in the other thread
https://lore.kernel.org/lkml/87im8038v7.fsf@xxxxxxxxxxxxxxxxxxxxx/

Best Regards,
Petr