On Tue, Oct 16, 2018 at 01:40:06PM +0200, Petr Mladek wrote: > On Tue 2018-10-16 09:27:19, Peter Zijlstra wrote: > > Instead of this tinkering around the edges, why don't you make the main > > logbuf a lockless ringbuffer and then delegate the actual printing of > > that buffer to a kthread, except for earlycon, which can do synchronous > > output. > > In fact, there is no problem with printk log buffer. This patchset > tries to avoid deadlock caused by console-specific locks > used by console->write() methods. > > By other words, we neither need printk_safe or lockless log buffer > to fix this prolem. Instead, we need either printk_deferred context > or lockless consoles. If you have a lockless buffer and a trailing printk thread, that's deferred. And earlycon _should_ be lockless (yes, I know, some suck) But if you do this deferred nonsense that's currently in printk, then you risk never seeing the message -- the same problem I have with the whole printk_safe thing too. Printing _after_ the fact is horrible for robustness.
