From owner-freebsd-hackers  Fri Jul 27 17:25:19 2001
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Date: Fri, 27 Jul 2001 20:23:37 -0400 (EDT)
From: Zhihui Zhang <zzhang@cs.binghamton.edu>
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To: Terry Lambert <tlambert2@mindspring.com>
Cc: Bosko Milekic <bmilekic@technokratis.com>,
	Alfred Perlstein <bright@mu.org>,
	vishwanath pargaonkar <vishubp@yahoo.com>,
	freebsd-hackers@FreeBSD.ORG
Subject: Re: cluster size
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I thought doing a memory free is always safe in an interrupt context. Now
it seems doing an allocation of memory is safe too.  Does MCLGET() call
vm_page_alloc() or malloc() eventually?  If so, it might block.

-Zhihui

On Thu, 26 Jul 2001, Terry Lambert wrote:

> Bosko Milekic wrote:
> > > > Er, wouldn't that be the only way for cards to refil thier DMA
> > > > recieve buffers?
> > >
> > > Look at the Tigon II and FXP drivers.  The allocations in
> > > the macros turn into m_get, not m_clusterget.
> > 
> >         From if_fxp.c (fxp_add_rfabuf(), sometimes called from fxp_intr()):
> > 
> >         MGETHDR(...);  <-- get mbuf
> >         if (m != NULL) {
> >                 MCLGET(...); <-- get cluster
> >                 ...
> >         }
> 
> Yes, I had misread things.  Alfred pointed this out to me in
> person, earlier.  I had been reading the jumbogram code,
> which uses a seperate buffer space, and then just incorrectly
> assumed.
> 
> Thanks for getting thecorrection into the list archives, so
> that future readers will be less confused: you spared me
> having to do the same.
> 
> -- Terry
> 
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