From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>,
Martin Schwidefsky <schwidefsky@de.ibm.com>,
linux-s390@vger.kernel.org, linux-kernel@vger.kernel.org,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Peter Oberparleiter <oberpar@linux.ibm.com>
Subject: Re: [PATCH] s390/fault: use wake_up_klogd() in bust_spinlocks()
Date: Thu, 25 Oct 2018 15:48:04 +0900 [thread overview]
Message-ID: <20181025064804.GA20702@jagdpanzerIV> (raw)
In-Reply-To: <20181025062800.GB4037@osiris>
On (10/25/18 08:28), Heiko Carstens wrote:
[..]
> > int loglevel_save = console_loglevel;
> > - console_unblank();
> > - oops_in_progress = 0;
> > - /*
> > - * OK, the message is on the console. Now we call printk()
> > - * without oops_in_progress set so that printk will give klogd
> > - * a poke. Hold onto your hats...
> > - */
> > +
> > console_loglevel = 15;
> > - printk(" ");
> > + console_unblank();
> > console_loglevel = loglevel_save;
> > + oops_in_progress = 0;
> > + wake_up_klogd();
> > }
>
> With your patch this looks nearly like the common code variant. I did
> some code archaeology and this function is unchanged since ~17 years.
> When it was introduced it was close to identical to the x86 variant.
> All other architectures use the common code variant in the
> meantime. So if we change this I'd prefer that we switch s390 to the
> common code variant as well.
Right. I couldn't clearly understand what was so special that s390
bust_spinlock() was doing, but assumed that this `console_loglevel'
manipulation probably was somehow important to s390. Though this
console_loglevel adjustment is not 100% guaranteed to make any difference,
because of the way console_unblank() works: if it can't lock console_sem
and it sees oops_in_progress then it does nothing; it doesn't even print
logbuf messages to the consoles. If, however, console_sem is not locked,
then it does print pending logbuf messages, with temporarily verbose
console_loglevel. I concluded that this might be important to you in
one way or another.
> Right now I can't see a reason for not doing that, but I might be
> wrong of course. So, could you please provide a new version which just
> removes this variant and makes s390 use the generic one too.
>
> We'll see if there is any fallout...
Will do! Sounds good.
-ss
next prev parent reply other threads:[~2018-10-25 6:48 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-10-24 4:30 [PATCH] s390/fault: use wake_up_klogd() in bust_spinlocks() Sergey Senozhatsky
2018-10-24 4:34 ` Sergey Senozhatsky
2018-10-25 6:28 ` Heiko Carstens
2018-10-25 6:48 ` Sergey Senozhatsky [this message]
2018-10-25 7:05 ` Sergey Senozhatsky
2018-10-25 8:11 ` Heiko Carstens
2018-10-25 8:28 ` Sergey Senozhatsky
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