From: Inaky Perez-Gonzalez <inaky@linux.intel.com>
To: Alan <alan@lxorguk.ukuu.org.uk>
Cc: Christoph Hellwig <hch@infradead.org>,
Arjan van de Ven <arjan@infradead.org>,
mingo@redhat.com, akpm@osdl.org, linux-kernel@vger.kernel.org
Subject: Re: [patch 0/2] semaphores: add down_interruptible_timeout() and asm-generic/semaphore.h
Date: Mon, 26 Feb 2007 17:57:11 -0800 [thread overview]
Message-ID: <200702261757.11968.inaky@linux.intel.com> (raw)
In-Reply-To: <20070227021803.38c8591f@lxorguk.ukuu.org.uk>
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...
next prev parent reply other threads:[~2007-02-27 1:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-02-27 0:13 [patch 0/2] semaphores: add down_interruptible_timeout() and asm-generic/semaphore.h inaky
2007-02-27 0:13 ` [patch 1/2] semaphores: Add down_interruptible_timeout() inaky
2007-02-27 0:13 ` [patch 2/2] semaphores: all arches use include/asm-generic/semaphore.h inaky
2007-02-27 0:33 ` [patch 0/2] semaphores: add down_interruptible_timeout() and asm-generic/semaphore.h Christoph Hellwig
2007-02-27 0:54 ` Inaky Perez-Gonzalez
2007-02-27 2:18 ` Alan
2007-02-27 1:57 ` Inaky Perez-Gonzalez [this message]
2007-02-27 20:45 ` Ingo Oeser
2007-03-03 1:17 ` Inaky Perez-Gonzalez
2007-02-27 20:24 ` Andrew Morton
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200702261757.11968.inaky@linux.intel.com \
--to=inaky@linux.intel.com \
--cc=akpm@osdl.org \
--cc=alan@lxorguk.ukuu.org.uk \
--cc=arjan@infradead.org \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox