From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Cort Dougan <cort@fsmlabs.com>, <linuxppc-dev@lists.linuxppc.org>
Subject: Re: i8259.c spinlocks unnecessary
Date: Sat, 29 Jun 2002 15:55:42 +0200 [thread overview]
Message-ID: <20020629135542.31287@192.168.4.1> (raw)
In-Reply-To: <20020628152929.K3851@host110.fsmlabs.com>
>
>I looked through the 8259 code and I believe the spinlocks there are
>unnecessary. The code is covered by a spinlock when called from irq.c.
>
>I instrumented the code and after running quite some time my code review
>matches what I've seen.
>
>Anyone comment? Does someone want to remove them?
irc.c don't have a global spinlock, only per-desc locks, so you can well
have one CPU dealing with an incoming interrupt and another CPU doing
a disable/enable_irq() on a different interrupt at the same time for
example. My understanding is that i8259 should be protected against
such races.
Ben.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
next prev parent reply other threads:[~2002-06-29 13:55 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2002-06-28 21:29 i8259.c spinlocks unnecessary Cort Dougan
2002-06-29 13:55 ` Benjamin Herrenschmidt [this message]
2002-06-29 14:28 ` Benjamin Herrenschmidt
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