From: Nick Piggin <nickpiggin@yahoo.com.au>
To: Kumar Gala <kumar.gala@freescale.com>
Cc: LKML list <linux-kernel@vger.kernel.org>
Subject: Re: return value of ptep_get_and_clear
Date: Thu, 07 Apr 2005 02:48:59 +1000 [thread overview]
Message-ID: <425412FB.7030209@yahoo.com.au> (raw)
In-Reply-To: <a0b2cb42ff815dcf964b7a728f638b87@freescale.com>
Kumar Gala wrote:
> ptep_get_and_clear has a signature that looks something like:
>
> static inline pte_t ptep_get_and_clear(struct mm_struct *mm, unsigned
> long addr,
> pte_t *ptep)
>
> It appears that its suppose to return the pte_t pointed to by ptep
> before its modified. Why do we bother doing this? The caller seems
> perfectly able to dereference ptep and hold on to it. Am I missing
> something here?
>
You need to be able to *atomically* clear the pte and retrieve the
old value.
Nick
--
SUSE Labs, Novell Inc.
next prev parent reply other threads:[~2005-04-06 16:49 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-04-06 16:38 return value of ptep_get_and_clear Kumar Gala
2005-04-06 16:48 ` Nick Piggin [this message]
2005-04-06 17:09 ` Christoph Lameter
2005-04-06 17:55 ` Kumar Gala
2005-04-06 17:09 ` Brian Gerst
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=425412FB.7030209@yahoo.com.au \
--to=nickpiggin@yahoo.com.au \
--cc=kumar.gala@freescale.com \
--cc=linux-kernel@vger.kernel.org \
/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