linux-kernel - Re: [patch 0/2] semaphores: add down_interruptible

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]

Date:	Mon, 26 Feb 2007 17:57:11 -0800
From:	Inaky Perez-Gonzalez <inaky@...ux.intel.com>
To:	Alan <alan@...rguk.ukuu.org.uk>
Cc:	Christoph Hellwig <hch@...radead.org>,
	Arjan van de Ven <arjan@...radead.org>, mingo@...hat.com,
	akpm@...l.org, linux-kernel@...r.kernel.org
Subject: Re: [patch 0/2] semaphores: add down_interruptible_timeout() and asm-generic/semaphore.h

On Monday 26 February 2007 18:18, Alan wrote:
> > Yeah, I need semaphore. This is a hw register that says when the hw
> > is ready to accept a new command. Code that wants to send commands has
> > to down the semaphore and then send it. When hw is ready to get a new
> > command, it sends and IRQ and the IRQ up()s the semaphore.
>
> So you need a mutex not a semaphore

Theoretically I could use a mutex. Practically it would trigger ugly
complications. Only the owner can unlock a mutex (for example), so
I could not unlock from an IRQ handler -- not to mention that the
semantic rules outlined in Documentation/mutex-design.txt explicitly
forbid IRQ usage. 

And then, this is what semaphores where designed for, as gates :)
for once that I get to use a semaphore properly...
-
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/