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From: Michael Schmitz <schmitzmic@gmail.com>
To: Arnd Bergmann <arnd@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>,
	scsi <linux-scsi@vger.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
	Arnd Bergmann <arnd@arndb.de>, Jakub Kicinski <kuba@kernel.org>,
	Christoph Hellwig <hch@infradead.org>,
	Marek Szyprowski <m.szyprowski@samsung.com>,
	Robin Murphy <robin.murphy@arm.com>,
	Linux IOMMU <iommu@lists.linux-foundation.org>,
	Khalid Aziz <khalid@gonehiking.org>,
	"Maciej W . Rozycki" <macro@orcam.me.uk>,
	Matt Wang <wwentao@vmware.com>,
	Miquel van Smoorenburg <mikevs@xs4all.net>,
	Mark Salyzyn <salyzyn@android.com>,
	linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
	Linux-Arch <linux-arch@vger.kernel.org>,
	alpha <linux-alpha@vger.kernel.org>,
	linux-m68k <linux-m68k@lists.linux-m68k.org>,
	Parisc List <linux-parisc@vger.kernel.org>,
	Denis Efremov <efremov@linux.com>,
	Michael Ellerman <mpe@ellerman.id.au>,
	John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Subject: Re: [PATCH v2 3/3] arch/*/: remove CONFIG_VIRT_TO_BUS
Date: Wed, 29 Jun 2022 11:09:00 +1200	[thread overview]
Message-ID: <9f812d3d-0fcd-46e6-6d7e-6d4bf66f24ab@gmail.com> (raw)
In-Reply-To: <CAK8P3a1rxEVwVF5U-PO6pQkfURU5Tro1Qp8SPUfHEV9jjWOmCQ@mail.gmail.com>

Hi Arnd,

On 29/06/22 09:50, Arnd Bergmann wrote:
> On Tue, Jun 28, 2022 at 11:03 PM Michael Schmitz <schmitzmic@gmail.com> wrote:
>> On 28/06/22 19:03, Geert Uytterhoeven wrote:
>>>> The driver allocates bounce buffers using kmalloc if it hits an
>>>> unaligned data buffer - can such buffers still even happen these days?
>>> No idea.
>> Hmmm - I think I'll stick a WARN_ONCE() in there so we know whether this
>> code path is still being used.
> kmalloc() guarantees alignment to the next power-of-two size or
> KMALLOC_MIN_ALIGN, whichever is bigger. On m68k this means it
> is cacheline aligned.

And all SCSI buffers are allocated using kmalloc? No way at all for user 
space to pass unaligned data?

(SCSI is a weird beast - I have used a SCSI DAT tape driver many many 
years ago, which broke all sorts of assumptions about transfer block 
sizes ... but that might actually have been in the v0.99 days, many 
rewrites of SCSI midlevel ago).

Just being cautious, as getting any of this tested will be a stretch.

Cheers,

     Michael

>
>        Arnd

  reply	other threads:[~2022-06-28 23:09 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2022-06-17 12:57 [PATCH v2 0/3] phase out CONFIG_VIRT_TO_BUS Arnd Bergmann
2022-06-17 12:57 ` [PATCH v2 1/3] scsi: dpt_i2o: drop stale VIRT_TO_BUS dependency Arnd Bergmann
2022-06-21  8:43   ` Hannes Reinecke
2022-06-17 12:57 ` [PATCH v2 2/3] scsi: BusLogic remove bus_to_virt Arnd Bergmann
2022-06-17 14:02   ` Robin Murphy
2022-06-21  8:45   ` Hannes Reinecke
2022-06-21 21:56   ` Khalid Aziz
2022-06-23 14:47     ` Arnd Bergmann
2022-06-24 15:38       ` Khalid Aziz
2022-06-24 15:43         ` Arnd Bergmann
2022-06-17 12:57 ` [PATCH v2 3/3] arch/*/: remove CONFIG_VIRT_TO_BUS Arnd Bergmann
2022-06-18  1:06   ` Michael Schmitz
2022-06-24  9:10     ` Arnd Bergmann
2022-06-26  5:21       ` Michael Schmitz
2022-06-26  8:36         ` Arnd Bergmann
2022-06-27  8:09           ` Michael Schmitz
2022-06-27  8:26     ` Geert Uytterhoeven
2022-06-27 21:12       ` Michael Schmitz
2022-06-28  3:25         ` Michael Schmitz
2022-06-28  7:03           ` Geert Uytterhoeven
2022-06-28 21:03             ` Michael Schmitz
2022-06-28 21:50               ` Arnd Bergmann
2022-06-28 23:09                 ` Michael Schmitz [this message]
2022-06-28 23:50                   ` Bart Van Assche
2022-06-29  0:01                     ` Michael Schmitz
2022-06-29  0:14                       ` Michael Schmitz
2022-06-29  6:21                   ` Christoph Hellwig
2022-06-30 19:21                     ` Michael Schmitz
2022-06-30  8:04                   ` David Laight
2022-06-30  9:40                     ` Christophe Leroy
2022-06-30 10:32                       ` David Laight
2022-06-28  7:08           ` Arnd Bergmann
2022-06-28 21:38             ` Michael Schmitz
2022-06-28 21:55               ` Arnd Bergmann
2022-06-28 23:43                 ` Michael Schmitz
2022-06-29  6:25               ` Christoph Hellwig
2022-06-30 19:26                 ` Michael Schmitz

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