From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Pekka Enberg <penberg@gmail.com>
Cc: "Bouchard, Sebastien" <Sebastien.Bouchard@ca.kontron.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
"Lorenzini, Mario" <mario.lorenzini@ca.kontron.com>,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: Patch of a new driver for kernel 2.4.x that need review
Date: Thu, 23 Jun 2005 22:42:12 +0100 [thread overview]
Message-ID: <1119546538.17063.18.camel@localhost.localdomain> (raw)
In-Reply-To: <84144f02050622130424379bf3@mail.gmail.com>
> > + if (check_region(TLCLK_BASE, 8)) {
> > + printk(KERN_ERR
> > + "telclock: I/O region already used by another
> > driver!\n");
> > + return -EBUSY;
> > + } else {
> > + request_region(TLCLK_BASE, 8, "telclock");
>
> request_region can fail too so you'd better handle that.
check_region() is essentially historical. It used to be that
check_region could fail and request_region did not. Once modules arrived
it becomes possible for drivers to race each other for resources so
request_region now atomically (with respect to itself) checks and if
available allocates a region.
check_region() shouldn't be used except for special cases where you
really want to see a space is free without requesting it. Even then if
you need to do any operation on the space while it is free you need to
request/act/release the region nto check_region for it.
Alan
next prev parent reply other threads:[~2005-06-23 21:53 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-06-22 15:12 Patch of a new driver for kernel 2.4.x that need review Bouchard, Sebastien
2005-06-22 19:43 ` Pekka Enberg
2005-06-22 20:32 ` Willy Tarreau
2005-06-22 20:59 ` Bill Gatliff
2005-06-22 21:58 ` Willy Tarreau
2005-06-23 4:58 ` Pekka Enberg
2005-06-23 4:16 ` Pekka J Enberg
2005-06-23 4:49 ` Willy Tarreau
2005-07-06 21:11 ` Mark Gross
2005-07-07 6:00 ` Pekka J Enberg
2005-07-07 6:50 ` Dmitry Torokhov
2005-07-07 6:55 ` Pekka J Enberg
2005-07-07 7:13 ` Dmitry Torokhov
2005-07-07 7:43 ` Pekka J Enberg
2005-07-07 6:10 ` Pekka J Enberg
2005-06-22 20:04 ` Pekka Enberg
2005-06-23 21:42 ` Alan Cox [this message]
2005-06-22 21:18 ` Jesper Juhl
2005-07-06 21:14 ` Mark Gross
2005-07-06 22:49 ` randy_dunlap
2005-07-06 22:57 ` Greg KH
2005-08-08 15:35 ` Mark Gross
2005-08-09 7:17 ` Pekka Enberg
2005-08-09 16:56 ` Mark Gross
2005-08-09 17:51 ` Nishanth Aravamudan
-- strict thread matches above, loose matches on Subject: below --
2005-07-07 8:15 moreau francis
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