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From: Geert Uytterhoeven <geert@linux-m68k.org>
To: Al Viro <viro@zeniv.linux.org.uk>
Cc: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Linux FS Devel <linux-fsdevel@vger.kernel.org>
Subject: Re: [PATCH 11/20] amifb: get rid of pointless access_ok() calls
Date: Thu, 14 May 2020 22:21:46 +0200	[thread overview]
Message-ID: <CAMuHMdV78Y2Y_vkvbs2nt5LjM7D9te3ozr71_o2uGoNHSK4u=Q@mail.gmail.com> (raw)
In-Reply-To: <20200514174131.GD23230@ZenIV.linux.org.uk>

Hi Al,

On Thu, May 14, 2020 at 7:43 PM Al Viro <viro@zeniv.linux.org.uk> wrote:
> On Thu, May 14, 2020 at 04:25:35PM +0200, Bartlomiej Zolnierkiewicz wrote:
> > Thank you for in-detail explanations, for this patch:
> >
> > Acked-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
> >
> > Could you also please take care of adding missing checks for {get,put}_user()
> > failures later?
>
> Umm...  OK; put_user() side is trivial -  the interesting part is what to do
> about get_user() failures halfway through.  Right now it treats them as
> "we'd read zeroes".  On anything else I would say "screw it, memdup_user()
> the damn thing on the way in and copy from there", but... Amiga has how
> much RAM, again?

In theory, up to 3.5 GiB ;-)
In practice, 16 MiB is already a lot (mine has 12).

> OTOH, from my reading of that code it does appear to be limited to
> 4Kb of data to copy, so it's probably OK...  Hell knows - I'm really
> confused by those #ifdef __mc68000__ in there; the driver *is*
> amiga-only:
> obj-$(CONFIG_FB_AMIGA)            += amifb.o c2p_planar.o
> config FB_AMIGA
>         tristate "Amiga native chipset support"
>         depends on FB && AMIGA
> and AMIGA is defined only in arch/m68k/Kconfig.machine.  So how the
> hell can it *not* be true?  OTOH, it looks like hand-optimized
> asm equivalents of C they have in #else, so that #else might be
> meant to document what's going on...

These #ifdefs are relics from APUS (Amiga Power-Up System), which
added a PPC board.  APUS support was killed off a long time ago,
when arch/ppc/ was still king, but these #ifdefs were missed, because
they didn't test for CONFIG_APUS.

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

  reply	other threads:[~2020-05-14 20:22 UTC|newest]

Thread overview: 42+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-09 23:41 [PATCHES] uaccess simple access_ok() removals Al Viro
2020-05-09 23:45 ` [PATCH 01/20] dlmfs_file_write(): get rid of pointless access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 02/20] fat_dir_ioctl(): hadn't needed that access_ok() for more than a decade Al Viro
2020-05-09 23:45   ` [PATCH 03/20] btrfs_ioctl_send(): don't bother with access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 04/20] FIEMAP: " Al Viro
2020-05-10  7:02     ` Christoph Hellwig
2020-05-13 19:02       ` Al Viro
2020-05-13 19:38         ` Christoph Hellwig
2020-05-29 15:01           ` Al Viro
2020-05-09 23:45   ` [PATCH 05/20] tomoyo_write_control(): get rid of pointless access_ok() Al Viro
2020-05-10  0:50     ` Tetsuo Handa
2020-05-10  0:57       ` Linus Torvalds
2020-05-10  1:04         ` Tetsuo Handa
2020-05-10  3:01         ` Al Viro
2020-05-09 23:45   ` [PATCH 06/20] n_hdlc_tty_read(): remove " Al Viro
2020-05-15 10:53     ` Greg Kroah-Hartman
2020-05-09 23:45   ` [PATCH 07/20] nvram: drop useless access_ok() Al Viro
2020-05-15 10:54     ` Greg Kroah-Hartman
2020-05-09 23:45   ` [PATCH 08/20] cm4000_cs.c cmm_ioctl(): get rid of pointless access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 09/20] drivers/fpga/dfl-fme-pr.c: " Al Viro
2020-05-09 23:45   ` [PATCH 10/20] drivers/fpga/dfl-afu-dma-region.c: " Al Viro
2020-05-09 23:45   ` [PATCH 11/20] amifb: get rid of pointless access_ok() calls Al Viro
2020-05-14 13:45     ` Bartlomiej Zolnierkiewicz
2020-05-14 14:07       ` Al Viro
2020-05-14 14:25         ` Bartlomiej Zolnierkiewicz
2020-05-14 17:41           ` Al Viro
2020-05-14 20:21             ` Geert Uytterhoeven [this message]
2020-05-09 23:45   ` [PATCH 12/20] omapfb: " Al Viro
2020-05-14 13:39     ` Bartlomiej Zolnierkiewicz
2020-05-09 23:45   ` [PATCH 13/20] drivers/crypto/ccp/sev-dev.c: get rid of pointless access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 14/20] via-pmu: don't bother with access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 15/20] drm_read(): get rid of pointless access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 16/20] efi_test: " Al Viro
2020-05-09 23:45   ` [PATCH 17/20] lpfc_debugfs: " Al Viro
2020-05-09 23:45   ` [PATCH 18/20] usb: get rid of pointless access_ok() calls Al Viro
2020-05-15 10:53     ` Greg Kroah-Hartman
2020-05-09 23:45   ` [PATCH 19/20] hfi1: get rid of pointless access_ok() Al Viro
2020-05-09 23:45   ` [PATCH 4/4] vmci_host: " Al Viro
2020-05-15 10:53     ` Greg Kroah-Hartman
2020-05-10  0:34 ` [PATCHES] uaccess simple access_ok() removals Linus Torvalds
2020-05-10  3:27   ` Al Viro
2020-05-10 14:34 ` David Laight

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