From: Christoph Hellwig <hch@infradead.org>
To: Nathan Lynch <ntl@pobox.com>
Cc: Roland Dreier <rdreier@cisco.com>,
openfabrics-ewg@openib.org, openib-general@openib.org,
linux-kernel@vger.kernel.org,
Christoph Hellwig <hch@infradead.org>,
linuxppc-dev@ozlabs.org, raisch@de.ibm.com,
Hoang-Nam Nguyen <hnguyen@linux.vnet.ibm.com>
Subject: Re: [PATCH/RFC 2.6.21 3/5] ehca: completion queue: remove use of do_mmap()
Date: Thu, 11 Jan 2007 19:43:46 +0000 [thread overview]
Message-ID: <20070111194346.GA29607@infradead.org> (raw)
In-Reply-To: <20070111194054.GA11770@localdomain>
On Thu, Jan 11, 2007 at 01:40:54PM -0600, Nathan Lynch wrote:
> Christoph Hellwig wrote:
> > On Thu, Jan 11, 2007 at 08:08:36PM +0100, Hoang-Nam Nguyen wrote:
> >
> > > spin_lock_irqsave(&ehca_cq_idr_lock, flags);
> > > while (my_cq->nr_callbacks)
> > > yield();
> >
> > Calling yield is a very bad idea in general. You should probably
> > add a waitqueue that gets woken when nr_callbacks reaches zero to
> > sleep effectively here.
>
> Isn't that code outright buggy? Calling into the scheduler with a
> spinlock held and local interrupts disabled...
Umm, yes - of course. I missed the spin_lock_irqsave line just above.
WARNING: multiple messages have this Message-ID (diff)
From: Christoph Hellwig <hch@infradead.org>
To: Nathan Lynch <ntl@pobox.com>
Cc: Christoph Hellwig <hch@infradead.org>,
Hoang-Nam Nguyen <hnguyen@linux.vnet.ibm.com>,
Roland Dreier <rdreier@cisco.com>,
linux-kernel@vger.kernel.org, linuxppc-dev@ozlabs.org,
openfabrics-ewg@openib.org, openib-general@openib.org,
raisch@de.ibm.com
Subject: Re: [PATCH/RFC 2.6.21 3/5] ehca: completion queue: remove use of do_mmap()
Date: Thu, 11 Jan 2007 19:43:46 +0000 [thread overview]
Message-ID: <20070111194346.GA29607@infradead.org> (raw)
In-Reply-To: <20070111194054.GA11770@localdomain>
On Thu, Jan 11, 2007 at 01:40:54PM -0600, Nathan Lynch wrote:
> Christoph Hellwig wrote:
> > On Thu, Jan 11, 2007 at 08:08:36PM +0100, Hoang-Nam Nguyen wrote:
> >
> > > spin_lock_irqsave(&ehca_cq_idr_lock, flags);
> > > while (my_cq->nr_callbacks)
> > > yield();
> >
> > Calling yield is a very bad idea in general. You should probably
> > add a waitqueue that gets woken when nr_callbacks reaches zero to
> > sleep effectively here.
>
> Isn't that code outright buggy? Calling into the scheduler with a
> spinlock held and local interrupts disabled...
Umm, yes - of course. I missed the spin_lock_irqsave line just above.
next prev parent reply other threads:[~2007-01-11 19:44 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-01-11 19:08 [PATCH/RFC 2.6.21 3/5] ehca: completion queue: remove use of do_mmap() Hoang-Nam Nguyen
2007-01-11 19:20 ` Christoph Hellwig
2007-01-11 19:20 ` Christoph Hellwig
2007-01-11 19:40 ` Nathan Lynch
2007-01-11 19:43 ` Christoph Hellwig [this message]
2007-01-11 19:43 ` Christoph Hellwig
2007-01-11 19:56 ` Roland Dreier
2007-01-11 19:56 ` Roland Dreier
2007-01-12 15:23 ` Hoang-Nam Nguyen
2007-01-12 15:23 ` Hoang-Nam Nguyen
2007-01-12 15:36 ` Hoang-Nam Nguyen
2007-01-12 15:36 ` Hoang-Nam Nguyen
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