From: torvalds@transmeta.com (Linus Torvalds)
To: linux-kernel@vger.kernel.org
Subject: Re: Why is get_current() not const function?
Date: Mon, 17 Mar 2003 06:26:26 +0000 (UTC) [thread overview]
Message-ID: <b53pqi$ud9$1@penguin.transmeta.com> (raw)
In-Reply-To: 20030313061926.S3910@devserv.devel.redhat.com
In article <20030313061926.S3910@devserv.devel.redhat.com>,
Jakub Jelinek <jakub@redhat.com> wrote:
>
>Anyone remembers why get_current function (on arches which define
>current to get_current()) is not const
Because it makes no difference at all on x86, since gcc will ignore
"const" for inline functions. At least that used to be true.
> and why on x86-64
>the movq %%gs:0, %0 inline asm is volatile with "memory" clobber?
Can't help you on that one, but it looks like it uses various helper
functions for doing the x86-64 per-processor data structures, and I bet
those helper functions are shared by _other_ users who definitely want
to have their data properly re-read. Ie "current()" may be constant in
process context, but that sure isn't true about a lot of other things in
the per-processor data structures.
Linus
next prev parent reply other threads:[~2003-03-17 6:16 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-03-13 11:19 Why is get_current() not const function? Jakub Jelinek
2003-03-17 6:26 ` Linus Torvalds [this message]
[not found] <20030313061926.S3910@devserv.devel.redhat.com.suse.lists.linux.kernel>
2003-03-13 13:31 ` Andi Kleen
[not found] ` <b53pqi$ud9$1@penguin.transmeta.com.suse.lists.linux.kernel>
2003-03-17 17:26 ` Andi Kleen
2003-03-17 17:39 ` Jakub Jelinek
-- strict thread matches above, loose matches on Subject: below --
2003-03-17 19:11 Manfred Spraul
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