linux-kernel - Re: [RFC][PATCH 6/7] printk: use alternative printk buffers

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Message-ID: <20161005101850.GC23809@pathway.suse.cz>
Date:   Wed, 5 Oct 2016 12:18:50 +0200
From:   Petr Mladek <pmladek@...e.com>
To:     Sergey Senozhatsky <sergey.senozhatsky.work@...il.com>
Cc:     Sergey Senozhatsky <sergey.senozhatsky@...il.com>,
        Jan Kara <jack@...e.cz>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Tejun Heo <tj@...nel.org>, Calvin Owens <calvinowens@...com>,
        linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH 6/7] printk: use alternative printk buffers

On Wed 2016-10-05 10:36:57, Sergey Senozhatsky wrote:
> On (10/04/16 14:22), Petr Mladek wrote:
> [..]
> > 	if (retry && console_trylock())
> > 		goto again;
> > 
> > with a safe variant, something like
> > 
> > 	if (retry) {
> > 		local_irq_save(flags);
> > 		alt_printk_enter();
> > 		lock_failed = console_trylock();
> > 		alt_printk_exit();
> > 		local_irq_restore(flags);
> > 
> > 		if (!lock_failed)
> > 			goto again;
> > 	}
> > 
> > Or do I miss anything?
> 
> nope, you don't. that's close to what I do in v3.
> 
> > I am going to look at the second version of the patchset.
> 
> thanks a lot for your review!
> 
> I'll refresh the patch set a bit later this week. I think it's more
> or less in shape now.... well, still under the old name: alt_printk.

Note that I have stopped reviewing v2 after realizing that it
did not help to get rid of printk_deferred().

I would like to revisit the usefulness of this approach first.
The motivation at
https://lkml.kernel.org/r/20160928011845.GA753@swordfish
does not longer fly. We will still need to maintain all
the printk_deferred()/WARN_*DEFERRED calls.

Also let me to reply to the mail
https://lkml.kernel.org/r/20160930004832.GA547@swordfish
The examples do not look real to me.

I am not sure what is the real group of fixed problems
at the moment.

I am sad when writing this. I was really optimistic
about this patchset.

Best Regards,
Petr