From: Andrew Morton <akpm@zip.com.au>
To: Robert Love <rml@tech9.net>
Cc: Ingo Molnar <mingo@elte.hu>, george anzinger <george@mvista.com>,
Zwane Mwaikambo <zwane@linuxpower.ca>,
Trond Myklebust <trond.myklebust@fys.uio.no>,
Linus Torvalds <torvalds@transmeta.com>,
Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [patch] irqlock patch -G3. [was Re: odd memory corruption in2.5.27?]
Date: Tue, 23 Jul 2002 20:13:42 -0700 [thread overview]
Message-ID: <3D3E1B66.F17D8B9E@zip.com.au> (raw)
In-Reply-To: 1027472897.927.247.camel@sinai
Robert Love wrote:
>
> ...
> Attached is the patch George mentioned, against 2.5.27.
>
I'd agree with Robert on that. The idea should be that,
as much as possible, preempt "just works" as long as the
programmer sticks with standard SMP programming practices.
And yet here we have a case where a spin_unlock() will
go and turn on local interrupts. Only with CONFIG_PREEMPT,
and even then, extremely rarely.
Plus it would be nice to have an arch-independent way of
querying whether the current CPU has interrupts enabled.
I've needed that several times within debug/devel code.
Robert and George's patch doesn't seem to be optimal though - if
we're not going to preempt at spin_unlock() time, we need to
preempt at local_irq_restore() time. It'll be untrivial to fix
all this, but this very subtle change to the locking semantics
with CONFIG_PREEMPT is quite nasty.
-
next prev parent reply other threads:[~2002-07-24 3:02 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-07-23 6:23 odd memory corruption in 2.5.27? Zwane Mwaikambo
2002-07-23 6:24 ` Zwane Mwaikambo
2002-07-23 6:26 ` Zwane Mwaikambo
2002-07-23 7:57 ` Trond Myklebust
2002-07-23 8:54 ` Zwane Mwaikambo
2002-07-23 20:32 ` george anzinger
2002-07-23 20:47 ` William Lee Irwin III
2002-07-23 23:28 ` [patch] irqlock patch -G3. [was Re: odd memory corruption in 2.5.27?] Ingo Molnar
2002-07-23 23:53 ` george anzinger
2002-07-23 23:56 ` Linus Torvalds
2002-07-24 0:07 ` Ingo Molnar
2002-07-24 2:15 ` Linus Torvalds
2002-07-24 8:59 ` [patch] irqlock patch 2.5.27-H3 Ingo Molnar
2002-07-24 1:08 ` [patch] irqlock patch -G3. [was Re: odd memory corruption in 2.5.27?] Robert Love
2002-07-24 3:13 ` Andrew Morton [this message]
2002-07-24 3:18 ` [patch] irqlock patch -G3. [was Re: odd memory corruption in2.5.27?] Linus Torvalds
2002-07-24 7:13 ` Ingo Molnar
2002-07-24 7:34 ` Ingo Molnar
2002-07-24 8:00 ` [patch] irqlock patch -G3. [was Re: odd memory corruptionin2.5.27?] Andrew Morton
2002-07-24 7:54 ` Ingo Molnar
2002-07-24 8:03 ` William Lee Irwin III
2002-07-24 8:06 ` Ingo Molnar
2002-07-24 8:15 ` William Lee Irwin III
2002-07-24 8:17 ` Ingo Molnar
2002-07-24 16:40 ` Linus Torvalds
2002-07-24 16:49 ` Robert Love
2002-07-24 20:56 ` [patch] irqlock patch -G3. [was Re: odd memorycorruptionin2.5.27?] george anzinger
2002-07-24 7:37 ` [patch] irqlock patch -G3. [was Re: odd memory corruption in2.5.27?] Ingo Molnar
2002-07-24 6:52 ` odd memory corruption in 2.5.27? Zwane Mwaikambo
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