Re: [RFC][PATCHv2 2/4] printk: move printk_safe macros to printk header

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



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.



[Index of Archives]     [Kernel Newbies]     [Security]     [Netfilter]     [Bugtraq]     [Linux PPP]     [Linux FS]     [Yosemite News]     [MIPS Linux]     [ARM Linux]     [Linux Security]     [Linux RAID]     [Samba]     [Video 4 Linux]     [Linmodem]     [Device Mapper]     [Linux Kernel for ARM]

  Powered by Linux