linux-kernel - Re: [patch 2.6.25-rc5 1/2] gpiolib: dynamic gpio number allocation

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <200803131753.58733.david-b@pacbell.net>
Date:	Thu, 13 Mar 2008 16:53:58 -0800
From:	David Brownell <david-b@...bell.net>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	linux-kernel@...r.kernel.org, avorontsov@...mvista.com
Subject: Re: [patch 2.6.25-rc5 1/2] gpiolib:  dynamic gpio number allocation

On Thursday 13 March 2008, Andrew Morton wrote:
> On Thu, 13 Mar 2008 15:18:58 -0800
> David Brownell <david-b@...bell.net> wrote:
> 
> > On Thursday 13 March 2008, Andrew Morton wrote:
> > 
> > > hm.  I suppose that if someone want a huge number of GPIOs then we can
> > > convert this to a bitmap or an IDR tree easily enough.
> > 
> > Actually, I tried IDRs for a while and they broke platforms
> > which needed to initialize and use GPIOs early: before kmalloc
> > would work.  A real PITA that was -- and slow too.
> 
> If IDRs were slow, that linear search will be glacial.

The slowness of IDRs was needing to use them for the
routine lookups ... versus the current array index,
which costs a fraction of an instruction cycle and
doesn't need separate locks.

Or were you implying they should be used for something
other than mapping GPIO numbers to controllers/state?

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