From: Arnd Bergmann <arnd@arndb•de>
To: linuxppc-embedded@ozlabs•org
Cc: Clifford Wolf <clifford@clifford•at>
Subject: Re: Mem-2-Mem DMA - Generalized API
Date: Sat, 7 Jul 2007 15:28:00 +0200 [thread overview]
Message-ID: <200707071528.00449.arnd@arndb.de> (raw)
In-Reply-To: <20070707132748.GB32740@clifford.at>
On Saturday 07 July 2007, Clifford Wolf wrote:
> > > +=A0=A0=A0// make sure all pending requests have finished before retu=
rning
> > > +=A0=A0=A0down_write(&backend->unreg_sem);
> > > +=A0=A0=A0up_write(&backend->unreg_sem);
> > > +}
> >=20
> > This usage of rw semaphores looks fishy.=20
>=20
> yep. do you have a better idea how to implement this easily?
>=20
I'd guess what you really want is reference counting. Every request
that gets assigned to a backend should get a kref on that backend
and give that up once it gets released itself.
I guess you can then have one more reference that you get in
dmatransfer_register_backend and release in dmatransfer_unregister_backend.
When you release the last reference, you call complete(),
and dmatransfer_unregister_backend() ends with a wait_for_completion().
Arnd <><
next prev parent reply other threads:[~2007-07-07 13:30 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-24 19:39 Mem-2-Mem DMA - Generalized API Clifford Wolf
2007-06-24 20:21 ` Arnd Bergmann
2007-06-25 8:03 ` Clifford Wolf
2007-06-25 11:03 ` Matt Sealey
2007-06-25 12:53 ` Clemens Koller
2007-06-25 14:31 ` Matt Sealey
2007-06-25 17:00 ` Olof Johansson
2007-06-25 17:48 ` Clifford Wolf
2007-06-25 18:01 ` Clifford Wolf
2007-06-25 21:20 ` Matt Sealey
2007-07-04 9:05 ` Clifford Wolf
2007-07-04 10:11 ` Clemens Koller
2007-07-07 5:24 ` Timur Tabi
2007-07-07 8:41 ` Clifford Wolf
2007-07-07 13:08 ` Arnd Bergmann
2007-07-07 13:27 ` Clifford Wolf
2007-07-07 13:28 ` Arnd Bergmann [this message]
2007-07-07 13:34 ` Clifford Wolf
2007-07-11 9:35 ` Clifford Wolf
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