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Kars de Jong b0a72e78fc scsi: zorro_esp: Limit DMA transfers to 65536 bytes (except on Fastlane)
[ Upstream commit 02f7e9f351 ]

When using this driver on a Blizzard 1260, there were failures whenever DMA
transfers from the SCSI bus to memory of 65535 bytes were followed by a DMA
transfer of 1 byte. This caused the byte at offset 65535 to be overwritten
with 0xff. The Blizzard hardware can't handle single byte DMA transfers.

Besides this issue, limiting the DMA length to something that is not a
multiple of the page size is very inefficient on most file systems.

It seems this limit was chosen because the DMA transfer counter of the ESP
by default is 16 bits wide, thus limiting the length to 65535 bytes.
However, the value 0 means 65536 bytes, which is handled by the ESP and the
Blizzard just fine. It is also the default maximum used by esp_scsi when
drivers don't provide their own dma_length_limit() function.

The limit of 65536 bytes can be used by all boards except the Fastlane. The
old driver used a limit of 65532 bytes (0xfffc), which is reintroduced in
this patch.

Fixes: b7ded0e8b0 ("scsi: zorro_esp: Limit DMA transfers to 65535 bytes")
Link: https://lore.kernel.org/r/20191112175523.23145-1-jongk@linux-m68k.org
Signed-off-by: Kars de Jong <jongk@linux-m68k.org>
Reviewed-by: Finn Thain <fthain@telegraphics.com.au>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2020-01-04 19:17:37 +01:00
Documentation USB: documentation: flags on usb-storage versus UAS 2019-12-17 19:55:32 +01:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
arch powerpc/book3s64/hash: Add cond_resched to avoid soft lockup warning 2020-01-04 19:17:12 +01:00
block iocost: over-budget forced IOs should schedule async delay 2019-12-31 16:46:19 +01:00
certs PKCS#7: Refactor verify_pkcs7_signature() 2019-08-05 18:40:18 -04:00
crypto KEYS: asymmetric: return ENOMEM if akcipher_request_alloc() fails 2019-12-31 16:46:07 +01:00
drivers scsi: zorro_esp: Limit DMA transfers to 65536 bytes (except on Fastlane) 2020-01-04 19:17:37 +01:00
fs iomap: fix return value of iomap_dio_bio_actor on 32bit systems 2020-01-04 19:17:31 +01:00
include fs/quota: handle overflows of sysctl fs.quota.* and report as unsigned long 2020-01-04 19:17:25 +01:00
init Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security 2019-09-28 08:14:15 -07:00
ipc ipc/sem.c: convert to use built-in RCU list checking 2019-09-25 17:51:41 -07:00
kernel dma-mapping: fix handling of dma-ranges for reserved memory (again) 2020-01-04 19:17:00 +01:00
lib ubsan, x86: Annotate and allow __ubsan_handle_shift_out_of_bounds() in uaccess regions 2019-12-31 16:44:25 +01:00
mm mm: vmscan: protect shrinker idr replace with CONFIG_MEMCG 2019-12-31 16:46:07 +01:00
net can: j1939: j1939_sk_bind(): take priv after lock is held 2019-12-31 16:45:56 +01:00
samples samples: pktgen: fix proc_cmd command result check logic 2019-12-31 16:43:45 +01:00
scripts dtc: Use pkg-config to locate libyaml 2020-01-04 19:17:09 +01:00
security efi/efi_test: Lock down /dev/efi_test and require CAP_SYS_ADMIN 2019-10-31 09:40:21 +01:00
sound ASoC: soc-pcm: check symmetry before hw_params 2019-12-31 16:45:42 +01:00
tools selftests/powerpc: Skip tm-signal-sigreturn-nt if TM not available 2020-01-04 19:17:10 +01:00
usr kbuild: update compile-test header list for v5.4-rc2 2019-10-05 15:29:49 +09:00
virt KVM: arm/arm64: Properly handle faulting of device mappings 2019-12-31 16:46:24 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Modules updates for v5.4 2019-09-22 10:34:46 -07:00
.mailmap ARM: SoC fixes 2019-11-10 13:41:59 -08:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Remove Simon as Renesas SoC Co-Maintainer 2019-10-10 08:12:51 -07:00
Kbuild kbuild: do not descend to ./Kbuild when cleaning 2019-08-21 21:03:58 +09:00
Kconfig docs: kbuild: convert docs to ReST and rename to *.rst 2019-06-14 14:21:21 -06:00
MAINTAINERS Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-11-22 14:28:14 -08:00
Makefile Linux 5.4.7 2019-12-31 16:46:36 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.