Date: Fri, 22 Jun 2007 12:38:39 -0500
To: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: "upping" a semaphore from interrupt context?
Message-ID: <20070622173839.GB8398@iucha.net>
MIME-Version: 1.0
Content-Type: multipart/signed; micalg=pgp-sha1;
	protocol="application/pgp-signature"; boundary="Fba/0zbH8Xs+Fj9o"
Content-Disposition: inline
User-Agent: Mutt/1.5.13 (2006-08-11)
From: florin@iucha.net (Florin Iucha)
Sender: linux-kernel-owner@vger.kernel.org
Content-Length: 1409
Lines: 46


--Fba/0zbH8Xs+Fj9o
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
Content-Transfer-Encoding: quoted-printable

Hello,

I am writing a USB driver for some custom hardware, and I need to
synchronize between the user-space and the USB subsystem.  Can I
create a semaphore and "down" it in the reader then "up" it in the
completion handler?

I know the completion handler runs in interrupt context so you are not
allowed to acquire any semaphores: but can you release them?  Will the
waiting tasks wake up after the handler and its caller returned - IOW
will the waking up task run in interrupt context as well?

This is with Linux 2.4 (if it makes a difference).

Thanks,
florin

--=20
Bruce Schneier expects the Spanish Inquisition.
      http://geekz.co.uk/schneierfacts/fact/163

--Fba/0zbH8Xs+Fj9o
Content-Type: application/pgp-signature; name="signature.asc"
Content-Description: Digital signature
Content-Disposition: inline

-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.4.6 (GNU/Linux)

iD8DBQFGfAkQND0rFCN2b1sRAkirAKCGBvXAECuF+YDjdR/qYy8xGG7r5gCeLF5P
hdRJZzFVMot62SxE2qKiLtw=
=gqqX
-----END PGP SIGNATURE-----

--Fba/0zbH8Xs+Fj9o--
-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/