Date: Wed, 15 Feb 2006 11:07:32 -0500 (EST)
From: Alan Stern <stern@rowland.harvard.edu>
To: James Bottomley <James.Bottomley@SteelEye.com>, Greg KH <greg@kroah.com>
cc: Kernel development list <linux-kernel@vger.kernel.org>
Subject: Re: [linux-usb-devel] Re: Linux 2.6.16-rc3
In-Reply-To: <1139934883.14115.4.camel@mulgrave.il.steeleye.com>
Message-ID: <Pine.LNX.4.44L0.0602151103160.4598-100000@iolanthe.rowland.org>
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On Tue, 14 Feb 2006, James Bottomley wrote:

> On Mon, 2006-02-13 at 12:38 -0800, Greg KH wrote:
> > > - Nasty warnings from scsi about kobject-layer things being called
> > from
> > >   irq context.  James has a push-it-to-process-context patch which
> > sadly
> > >   assumes kmalloc() is immortal, but no other fix seems to have
> > offered
> > >   itself.
> > 
> > This has been the case for a long time.  I don't really think there is
> > a
> > rush to get this fixed, but I really like James's proposed patch.
> > It's
> > up to him if he feels it is ready for 2.6.16 or not.
> 
> Well, I can't solve the problem that it requires memory allocation from
> IRQ context to operate.  Based on that, it's an unsafe interface.  I'm
> going to put it inside SCSI for 2.6.16, since it's better than what we
> have now, but I don't think we can export it globally.

Could we perhaps make this safer and more general?

For instance, add to struct device a "pending puts" counter and a list
header (both protected by a global spinlock), and have a kernel thread
periodically check the list, doing put_device wherever needed.  How does
that sound?

Alan Stern

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