* Re: [GIT PULL] Btrfs
2013-09-13 12:15 ` Russell King
@ 2013-09-13 12:15 ` Russell King
2013-09-13 12:36 ` Geert Uytterhoeven
2013-09-13 15:06 ` Josh Boyer
2 siblings, 0 replies; 12+ messages in thread
From: Russell King @ 2013-09-13 12:15 UTC (permalink / raw)
To: Josh Boyer
Cc: Geert Uytterhoeven, Chris Mason, Mark Fasheh, Linus Torvalds,
linux-btrfs, Linux-Kernel@Vger. Kernel. Org, Linux-Arch
On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
> I'm not an ARM expert, so I don't know if ARM should use the
> asm-generic implementations, or just use __get_user/__put_user in all
> cases. I've CC'd rmk.
Why do we have uaccess-unaligned.h ? Normally, these kinds of things
are spawned by architectures which have problems with unaligned accesses,
ARM being one of them, but afaik we've never need this.
With the kernel-side trapping of unaligned accesses on older hardware,
we've always dealt with the normal accessor faulting.
From what I can tell in the git history, these unaligned put_user and
get_user have existed all the way back to the dawn of git use.
Can someone enlighten me why we have them?
--
Russell King
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [GIT PULL] Btrfs
2013-09-13 12:15 ` Russell King
2013-09-13 12:15 ` Russell King
@ 2013-09-13 12:36 ` Geert Uytterhoeven
2013-09-13 15:06 ` Josh Boyer
2 siblings, 0 replies; 12+ messages in thread
From: Geert Uytterhoeven @ 2013-09-13 12:36 UTC (permalink / raw)
To: Josh Boyer, Geert Uytterhoeven, Chris Mason, Mark Fasheh,
Linus Torvalds, linux-btrfs, Linux-Kernel@Vger. Kernel. Org,
Linux-Arch
On Fri, Sep 13, 2013 at 2:15 PM, Russell King <rmk@arm.linux.org.uk> wrote:
> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
>> I'm not an ARM expert, so I don't know if ARM should use the
>> asm-generic implementations, or just use __get_user/__put_user in all
>> cases. I've CC'd rmk.
>
> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> are spawned by architectures which have problems with unaligned accesses,
> ARM being one of them, but afaik we've never need this.
>
> With the kernel-side trapping of unaligned accesses on older hardware,
> we've always dealt with the normal accessor faulting.
>
> From what I can tell in the git history, these unaligned put_user and
> get_user have existed all the way back to the dawn of git use.
>
> Can someone enlighten me why we have them?
You removed the answer when trimming the quoted part:
| "Btrfs is the first user of __put_user_unaligned() outside the compat code,
__put_user_unaligned() is used in fs/compat.c, presumably because
alignment restrictions may differ between 32- and 64-bit versions of the
same CPU family.
No one seems to actully use __get_user_unaligned().
Gr{oetje,eeting}s,
Geert
--
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org
In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
-- Linus Torvalds
^ permalink raw reply [flat|nested] 12+ messages in thread* Re: [GIT PULL] Btrfs
2013-09-13 12:15 ` Russell King
2013-09-13 12:15 ` Russell King
2013-09-13 12:36 ` Geert Uytterhoeven
@ 2013-09-13 15:06 ` Josh Boyer
2013-09-13 15:06 ` Josh Boyer
2013-09-13 15:38 ` Josh Boyer
2 siblings, 2 replies; 12+ messages in thread
From: Josh Boyer @ 2013-09-13 15:06 UTC (permalink / raw)
To: Geert Uytterhoeven, Chris Mason, Mark Fasheh, Linus Torvalds,
linux-btrfs, Linux-Kernel@Vger. Kernel. Org, Linux-Arch
On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
>> I'm not an ARM expert, so I don't know if ARM should use the
>> asm-generic implementations, or just use __get_user/__put_user in all
>> cases. I've CC'd rmk.
>
> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> are spawned by architectures which have problems with unaligned accesses,
> ARM being one of them, but afaik we've never need this.
>
> With the kernel-side trapping of unaligned accesses on older hardware,
> we've always dealt with the normal accessor faulting.
>
> From what I can tell in the git history, these unaligned put_user and
> get_user have existed all the way back to the dawn of git use.
>
> Can someone enlighten me why we have them?
So while that gets sorted out, would it be safe to just do as Geert
did on m68k and put:
#define __put_user_unaligned(x, ptr) __put_user((x), (ptr))
in arch/arm/include/asm/uaccess.h, and let the normal accessors and
kernel-side trapping deal with things? I'm thinking that's a local
fix until something gets sorted upstream, but I don't want to do it if
it's going to break things.
josh
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [GIT PULL] Btrfs
2013-09-13 15:06 ` Josh Boyer
@ 2013-09-13 15:06 ` Josh Boyer
2013-09-13 15:38 ` Josh Boyer
1 sibling, 0 replies; 12+ messages in thread
From: Josh Boyer @ 2013-09-13 15:06 UTC (permalink / raw)
To: Geert Uytterhoeven, Chris Mason, Mark Fasheh, Linus Torvalds,
linux-btrfs, Linux-Kernel@Vger. Kernel. Org, Linux-Arch
On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
>> I'm not an ARM expert, so I don't know if ARM should use the
>> asm-generic implementations, or just use __get_user/__put_user in all
>> cases. I've CC'd rmk.
>
> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> are spawned by architectures which have problems with unaligned accesses,
> ARM being one of them, but afaik we've never need this.
>
> With the kernel-side trapping of unaligned accesses on older hardware,
> we've always dealt with the normal accessor faulting.
>
> From what I can tell in the git history, these unaligned put_user and
> get_user have existed all the way back to the dawn of git use.
>
> Can someone enlighten me why we have them?
So while that gets sorted out, would it be safe to just do as Geert
did on m68k and put:
#define __put_user_unaligned(x, ptr) __put_user((x), (ptr))
in arch/arm/include/asm/uaccess.h, and let the normal accessors and
kernel-side trapping deal with things? I'm thinking that's a local
fix until something gets sorted upstream, but I don't want to do it if
it's going to break things.
josh
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [GIT PULL] Btrfs
2013-09-13 15:06 ` Josh Boyer
2013-09-13 15:06 ` Josh Boyer
@ 2013-09-13 15:38 ` Josh Boyer
2013-09-13 15:58 ` Russell King
1 sibling, 1 reply; 12+ messages in thread
From: Josh Boyer @ 2013-09-13 15:38 UTC (permalink / raw)
To: Geert Uytterhoeven, Chris Mason, Mark Fasheh, Linus Torvalds,
linux-btrfs, Linux-Kernel@Vger. Kernel. Org, Linux-Arch,
Russell King
On Fri, Sep 13, 2013 at 11:06 AM, Josh Boyer <jwboyer@gmail.com> wrote:
> On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
>> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
>>> I'm not an ARM expert, so I don't know if ARM should use the
>>> asm-generic implementations, or just use __get_user/__put_user in all
>>> cases. I've CC'd rmk.
>>
>> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
>> are spawned by architectures which have problems with unaligned accesses,
>> ARM being one of them, but afaik we've never need this.
>>
>> With the kernel-side trapping of unaligned accesses on older hardware,
>> we've always dealt with the normal accessor faulting.
>>
>> From what I can tell in the git history, these unaligned put_user and
>> get_user have existed all the way back to the dawn of git use.
>>
>> Can someone enlighten me why we have them?
I somehow fail at email and dropped Russell from CC on accident. Sigh.
> So while that gets sorted out, would it be safe to just do as Geert
> did on m68k and put:
>
> #define __put_user_unaligned(x, ptr) __put_user((x), (ptr))
>
> in arch/arm/include/asm/uaccess.h, and let the normal accessors and
> kernel-side trapping deal with things? I'm thinking that's a local
> fix until something gets sorted upstream, but I don't want to do it if
> it's going to break things.
>
> josh
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [GIT PULL] Btrfs
2013-09-13 15:38 ` Josh Boyer
@ 2013-09-13 15:58 ` Russell King
2013-09-13 15:58 ` Russell King
2013-09-14 9:33 ` Heiko Carstens
0 siblings, 2 replies; 12+ messages in thread
From: Russell King @ 2013-09-13 15:58 UTC (permalink / raw)
To: Josh Boyer
Cc: Geert Uytterhoeven, Chris Mason, Mark Fasheh, Linus Torvalds,
linux-btrfs, Linux-Kernel@Vger. Kernel. Org, Linux-Arch
On Fri, Sep 13, 2013 at 11:38:15AM -0400, Josh Boyer wrote:
> On Fri, Sep 13, 2013 at 11:06 AM, Josh Boyer <jwboyer@gmail.com> wrote:
> > On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
> >> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
> >>> I'm not an ARM expert, so I don't know if ARM should use the
> >>> asm-generic implementations, or just use __get_user/__put_user in all
> >>> cases. I've CC'd rmk.
> >>
> >> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> >> are spawned by architectures which have problems with unaligned accesses,
> >> ARM being one of them, but afaik we've never need this.
> >>
> >> With the kernel-side trapping of unaligned accesses on older hardware,
> >> we've always dealt with the normal accessor faulting.
> >>
> >> From what I can tell in the git history, these unaligned put_user and
> >> get_user have existed all the way back to the dawn of git use.
> >>
> >> Can someone enlighten me why we have them?
>
> I somehow fail at email and dropped Russell from CC on accident. Sigh.
You're not the first to do that recently. I'm beginning to think it's
something someone has written into email clients to make them do in order
to piss me off. I mean, it's _hard_ to do - you have to manually edit the
recipients list to just drop one person.
> > So while that gets sorted out, would it be safe to just do as Geert
> > did on m68k and put:
> >
> > #define __put_user_unaligned(x, ptr) __put_user((x), (ptr))
> >
> > in arch/arm/include/asm/uaccess.h, and let the normal accessors and
> > kernel-side trapping deal with things? I'm thinking that's a local
> > fix until something gets sorted upstream, but I don't want to do it if
> > it's going to break things.
Yep, that should work just fine.
--
Russell King
ARM architecture Linux Kernel maintainer
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [GIT PULL] Btrfs
2013-09-13 15:58 ` Russell King
@ 2013-09-13 15:58 ` Russell King
2013-09-14 9:33 ` Heiko Carstens
1 sibling, 0 replies; 12+ messages in thread
From: Russell King @ 2013-09-13 15:58 UTC (permalink / raw)
To: Josh Boyer
Cc: Geert Uytterhoeven, Chris Mason, Mark Fasheh, Linus Torvalds,
linux-btrfs, Linux-Kernel@Vger. Kernel. Org, Linux-Arch
On Fri, Sep 13, 2013 at 11:38:15AM -0400, Josh Boyer wrote:
> On Fri, Sep 13, 2013 at 11:06 AM, Josh Boyer <jwboyer@gmail.com> wrote:
> > On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
> >> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
> >>> I'm not an ARM expert, so I don't know if ARM should use the
> >>> asm-generic implementations, or just use __get_user/__put_user in all
> >>> cases. I've CC'd rmk.
> >>
> >> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> >> are spawned by architectures which have problems with unaligned accesses,
> >> ARM being one of them, but afaik we've never need this.
> >>
> >> With the kernel-side trapping of unaligned accesses on older hardware,
> >> we've always dealt with the normal accessor faulting.
> >>
> >> From what I can tell in the git history, these unaligned put_user and
> >> get_user have existed all the way back to the dawn of git use.
> >>
> >> Can someone enlighten me why we have them?
>
> I somehow fail at email and dropped Russell from CC on accident. Sigh.
You're not the first to do that recently. I'm beginning to think it's
something someone has written into email clients to make them do in order
to piss me off. I mean, it's _hard_ to do - you have to manually edit the
recipients list to just drop one person.
> > So while that gets sorted out, would it be safe to just do as Geert
> > did on m68k and put:
> >
> > #define __put_user_unaligned(x, ptr) __put_user((x), (ptr))
> >
> > in arch/arm/include/asm/uaccess.h, and let the normal accessors and
> > kernel-side trapping deal with things? I'm thinking that's a local
> > fix until something gets sorted upstream, but I don't want to do it if
> > it's going to break things.
Yep, that should work just fine.
--
Russell King
ARM architecture Linux Kernel maintainer
^ permalink raw reply [flat|nested] 12+ messages in thread
* Re: [GIT PULL] Btrfs
2013-09-13 15:58 ` Russell King
2013-09-13 15:58 ` Russell King
@ 2013-09-14 9:33 ` Heiko Carstens
1 sibling, 0 replies; 12+ messages in thread
From: Heiko Carstens @ 2013-09-14 9:33 UTC (permalink / raw)
To: Russell King, Josh Boyer, Geert Uytterhoeven, Chris Mason,
Mark Fasheh, Linus Torvalds, linux-btrfs,
Linux-Kernel@Vger. Kernel. Org, Linux-Arch
On Fri, Sep 13, 2013 at 04:58:36PM +0100, Russell King wrote:
> On Fri, Sep 13, 2013 at 11:38:15AM -0400, Josh Boyer wrote:
> > On Fri, Sep 13, 2013 at 11:06 AM, Josh Boyer <jwboyer@gmail.com> wrote:
> > > On Fri, Sep 13, 2013 at 8:15 AM, Russell King <rmk@arm.linux.org.uk> wrote:
> > >> On Fri, Sep 13, 2013 at 07:53:21AM -0400, Josh Boyer wrote:
> > >>> I'm not an ARM expert, so I don't know if ARM should use the
> > >>> asm-generic implementations, or just use __get_user/__put_user in all
> > >>> cases. I've CC'd rmk.
> > >>
> > >> Why do we have uaccess-unaligned.h ? Normally, these kinds of things
> > >> are spawned by architectures which have problems with unaligned accesses,
> > >> ARM being one of them, but afaik we've never need this.
> > >>
> > >> With the kernel-side trapping of unaligned accesses on older hardware,
> > >> we've always dealt with the normal accessor faulting.
> > >>
> > >> From what I can tell in the git history, these unaligned put_user and
> > >> get_user have existed all the way back to the dawn of git use.
> > >>
> > >> Can someone enlighten me why we have them?
> >
> > I somehow fail at email and dropped Russell from CC on accident. Sigh.
>
> You're not the first to do that recently. I'm beginning to think it's
> something someone has written into email clients to make them do in order
> to piss me off. I mean, it's _hard_ to do - you have to manually edit the
> recipients list to just drop one person.
You configured your mail client to generate a "Mail-Followup-To:" header
field which actively asks other mail clients to remove you from replies.
So you only get what you ask for... ;)
I think the mutt "metoo" variable will change that, but I don't know
for sure.
^ permalink raw reply [flat|nested] 12+ messages in thread