From: Ingo Molnar <mingo@elte.hu>
To: David Miller <davem@davemloft.net>
Cc: sfr@canb.auug.org.au, tglx@linutronix.de, hpa@zytor.com,
peterz@infradead.org, linux-next@vger.kernel.org,
linux-kernel@vger.kernel.org, fweisbec@gmail.com,
linuxppc-dev@lists.ozlabs.org
Subject: Re: linux-next: PowerPC WARN_ON_ONCE() after merge of the final tree (tip related)
Date: Thu, 15 Apr 2010 09:32:56 +0200 [thread overview]
Message-ID: <20100415073256.GG9240@elte.hu> (raw)
In-Reply-To: <20100414.235557.123118153.davem@davemloft.net>
* David Miller <davem@davemloft.net> wrote:
> From: Ingo Molnar <mingo@elte.hu>
> Date: Thu, 15 Apr 2010 08:49:40 +0200
>
> > Btw., WARN_ON trapping on PowerPC is clearly a PowerPC bug - there's a good
> > reason we have WARN_ON versus BUG_ON - it should be fixed.
>
> I disagree, an implementation should be allowed to use the most
> efficient implementation possible for both interfaces.
It trades robustness for slightly better space/code efficiency.
Such a trap based mechanism exists on x86 as well and we use it for BUG_ON().
We intentionally dont use it to generate warnings and dont override __WARN(),
because it would blow up way too often when a warning triggers in some
sensitive codepath that cannot take a trap.
Anyway, the warning obviously has to be fixed - but the boot crash itself is
PowerPC's own doing.
Ingo
WARNING: multiple messages have this Message-ID (diff)
From: Ingo Molnar <mingo@elte.hu>
To: David Miller <davem@davemloft.net>
Cc: sfr@canb.auug.org.au, peterz@infradead.org, fweisbec@gmail.com,
linux-kernel@vger.kernel.org, linux-next@vger.kernel.org,
hpa@zytor.com, tglx@linutronix.de, linuxppc-dev@lists.ozlabs.org
Subject: Re: linux-next: PowerPC WARN_ON_ONCE() after merge of the final tree (tip related)
Date: Thu, 15 Apr 2010 09:32:56 +0200 [thread overview]
Message-ID: <20100415073256.GG9240@elte.hu> (raw)
In-Reply-To: <20100414.235557.123118153.davem@davemloft.net>
* David Miller <davem@davemloft.net> wrote:
> From: Ingo Molnar <mingo@elte.hu>
> Date: Thu, 15 Apr 2010 08:49:40 +0200
>
> > Btw., WARN_ON trapping on PowerPC is clearly a PowerPC bug - there's a good
> > reason we have WARN_ON versus BUG_ON - it should be fixed.
>
> I disagree, an implementation should be allowed to use the most
> efficient implementation possible for both interfaces.
It trades robustness for slightly better space/code efficiency.
Such a trap based mechanism exists on x86 as well and we use it for BUG_ON().
We intentionally dont use it to generate warnings and dont override __WARN(),
because it would blow up way too often when a warning triggers in some
sensitive codepath that cannot take a trap.
Anyway, the warning obviously has to be fixed - but the boot crash itself is
PowerPC's own doing.
Ingo
next prev parent reply other threads:[~2010-04-15 7:33 UTC|newest]
Thread overview: 34+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-04-15 6:12 linux-next: boot failure after merge of the final tree (tip related) Stephen Rothwell
2010-04-15 6:12 ` Stephen Rothwell
2010-04-15 6:48 ` Benjamin Herrenschmidt
2010-04-15 6:48 ` Benjamin Herrenschmidt
2010-04-15 6:49 ` linux-next: PowerPC WARN_ON_ONCE() " Ingo Molnar
2010-04-15 6:49 ` Ingo Molnar
2010-04-15 6:55 ` David Miller
2010-04-15 6:55 ` David Miller
2010-04-15 7:32 ` Ingo Molnar [this message]
2010-04-15 7:32 ` Ingo Molnar
2010-04-16 1:51 ` Benjamin Herrenschmidt
2010-04-16 1:51 ` Benjamin Herrenschmidt
2010-04-16 1:56 ` Benjamin Herrenschmidt
2010-04-16 1:56 ` Benjamin Herrenschmidt
2010-04-15 10:04 ` Stephen Rothwell
2010-04-15 10:04 ` Stephen Rothwell
2010-04-15 13:37 ` [PATCH] lockdep: Fix redundant_hardirqs_on incremented with irqs enabled Frederic Weisbecker
2010-04-27 7:32 ` Stephen Rothwell
2010-04-27 18:07 ` Frederic Weisbecker
2010-04-28 7:12 ` Stephen Rothwell
2010-04-15 13:00 ` linux-next: PowerPC WARN_ON_ONCE() after merge of the final tree (tip related) Frederic Weisbecker
2010-04-15 13:00 ` Frederic Weisbecker
2010-04-15 14:03 ` Ingo Molnar
2010-04-15 14:03 ` Ingo Molnar
2010-04-15 17:15 ` Frederic Weisbecker
2010-04-15 17:15 ` Frederic Weisbecker
2010-04-16 10:38 ` Peter Zijlstra
2010-04-16 10:38 ` Peter Zijlstra
2010-04-16 12:32 ` Frederic Weisbecker
2010-04-16 12:32 ` Frederic Weisbecker
2010-04-15 17:24 ` Frederic Weisbecker
2010-04-15 17:24 ` Frederic Weisbecker
2010-04-15 17:39 ` Ingo Molnar
2010-04-15 17:39 ` Ingo Molnar
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