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Jie Hai af12e209a9 dmaengine: hisilicon: Add multi-thread support for a DMA channel 
[ Upstream commit 2cbb95883c ]

When we get a DMA channel and try to use it in multiple threads it
will cause oops and hanging the system.

% echo 100 > /sys/module/dmatest/parameters/threads_per_chan
% echo 100 > /sys/module/dmatest/parameters/iterations
% echo 1 > /sys/module/dmatest/parameters/run
[383493.327077] Unable to handle kernel paging request at virtual
		address dead000000000108
[383493.335103] Mem abort info:
[383493.335103]   ESR = 0x96000044
[383493.335105]   EC = 0x25: DABT (current EL), IL = 32 bits
[383493.335107]   SET = 0, FnV = 0
[383493.335108]   EA = 0, S1PTW = 0
[383493.335109]   FSC = 0x04: level 0 translation fault
[383493.335110] Data abort info:
[383493.335111]   ISV = 0, ISS = 0x00000044
[383493.364739]   CM = 0, WnR = 1
[383493.367793] [dead000000000108] address between user and kernel
		address ranges
[383493.375021] Internal error: Oops: 96000044 [#1] PREEMPT SMP
[383493.437574] CPU: 63 PID: 27895 Comm: dma0chan0-copy2 Kdump:
		loaded Tainted: GO 5.17.0-rc4+ #2
[383493.457851] pstate: 204000c9 (nzCv daIF +PAN -UAO -TCO -DIT
		-SSBS BTYPE=--)
[383493.465331] pc : vchan_tx_submit+0x64/0xa0
[383493.469957] lr : vchan_tx_submit+0x34/0xa0

This occurs because the transmission timed out, and that's due
to data race. Each thread rewrite channels's descriptor as soon as
device_issue_pending is called. It leads to the situation that
the driver thinks that it uses the right descriptor in interrupt
handler while channels's descriptor has been changed by other
thread. The descriptor which in fact reported interrupt will not
be handled any more, as well as its tx->callback.
That's why timeout reports.

With current fixes channels' descriptor changes it's value only
when it has been used. A new descriptor is acquired from
vc->desc_issued queue that is already filled with descriptors
that are ready to be sent. Threads have no direct access to DMA
channel descriptor. In case of channel's descriptor is busy, try
to submit to HW again when a descriptor is completed. In this case,
vc->desc_issued may be empty when hisi_dma_start_transfer is called,
so delete error reporting on this. Now it is just possible to queue
a descriptor for further processing.

Fixes: e9f08b6525 ("dmaengine: hisilicon: Add Kunpeng DMA engine support")
Signed-off-by: Jie Hai <haijie1@huawei.com>
Acked-by: Zhou Wang <wangzhou1@hisilicon.com>
Link: https://lore.kernel.org/r/20220830062251.52993-4-haijie1@huawei.com
Signed-off-by: Vinod Koul <vkoul@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
2022-10-26 13:25:34 +02:00
arch ARM: dts: exynos: fix polarity of VBUS GPIO of Origen 2022-10-26 13:25:29 +02:00
block block: fix inflight statistics of part0 2022-10-26 13:25:11 +02:00
certs certs/blacklist_hashes.c: fix const confusion in certs blacklist 2022-06-22 14:13:17 +02:00
crypto KEYS: asymmetric: enforce SM2 signature use pkey algo 2022-08-21 15:16:22 +02:00
Documentation iio: ABI: Fix wrong format of differential capacitance channel ABI. 2022-10-26 13:25:30 +02:00
drivers dmaengine: hisilicon: Add multi-thread support for a DMA channel 2022-10-26 13:25:34 +02:00
fs nfsd: Fix a memory leak in an error handling path 2022-10-26 13:25:18 +02:00
include usb: common: move function's kerneldoc next to its definition 2022-10-26 13:25:31 +02:00
init Kconfig: Add option for asm goto w/ tied outputs to workaround clang-13 bug 2022-06-09 10:21:25 +02:00
ipc ipc/mqueue: use get_tree_nodev() in mqueue_get_tree() 2022-06-09 10:21:17 +02:00
kernel bpf: Ensure correct locking around vulnerable function find_vpid() 2022-10-26 13:25:21 +02:00
lib once: add DO_ONCE_SLOW() for sleepable contexts 2022-10-26 13:25:23 +02:00
LICENSES LICENSES/deprecated: add Zlib license text 2020-09-16 14:33:49 +02:00
mm mm/mmap: undo ->mmap() when arch_validate_flags() fails 2022-10-26 13:25:11 +02:00
net once: add DO_ONCE_SLOW() for sleepable contexts 2022-10-26 13:25:23 +02:00
samples x86: Prepare inline-asm for straight-line-speculation 2022-07-25 11:26:29 +02:00
scripts selinux: use "grep -E" instead of "egrep" 2022-10-26 13:25:17 +02:00
security hardening: Remove Clang's enable flag for -ftrivial-auto-var-init=zero 2022-10-26 13:25:12 +02:00
sound ALSA: hda/hdmi: Don't skip notification handling during PM operation 2022-10-26 13:25:27 +02:00
tools selftests/xsk: Avoid use-after-free on ctx 2022-10-26 13:25:20 +02:00
usr usr/include/Makefile: add linux/nfc.h to the compile-test coverage 2022-02-01 17:25:48 +01:00
virt KVM: SEV: add cache flush to solve SEV cache incoherency issues 2022-09-28 11:10:28 +02:00
.clang-format RDMA 5.10 pull request 2020-10-17 11:18:18 -07:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore kbuild: generate Module.symvers only when vmlinux exists 2021-05-19 10:12:59 +02:00
.mailmap mailmap: add two more addresses of Uwe Kleine-König 2020-12-06 10:19:07 -08:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Move Jason Cooper to CREDITS 2020-11-30 10:20:34 +01:00
Kbuild kbuild: rename hostprogs-y/always to hostprogs/always-y 2020-02-04 01:53:07 +09:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS MAINTAINERS: add Amir as xfs maintainer for 5.10.y 2022-07-02 16:39:22 +02:00
Makefile hardening: Remove Clang's enable flag for -ftrivial-auto-var-init=zero 2022-10-26 13:25:12 +02:00
README

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.