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AngeloGioacchino Del Regno e0a25be0d4 rpmsg: mtk_rpmsg: Fix circular locking dependency [ Upstream commit `353d921468` ] During execution of the worker that's used to register rpmsg devices we are safely locking the channels mutex but, when creating a new endpoint for such devices, we are registering a IPI on the SCP, which then makes the SCP to trigger an interrupt, lock its own mutex and in turn register more subdevices. This creates a circular locking dependency situation, as the mtk_rpmsg channels_lock will then depend on the SCP IPI lock. [ 15.447736] ====================================================== [ 15.460158] WARNING: possible circular locking dependency detected [ 15.460161] 5.17.0-next-20220324+ #399 Not tainted [ 15.460165] ------------------------------------------------------ [ 15.460166] kworker/0:3/155 is trying to acquire lock: [ 15.460170] ffff5b4d0eaf1308 (&scp->ipi_desc[i].lock){+.+.}-{4:4}, at: scp_ipi_lock+0x34/0x50 [mtk_scp_ipi] [ 15.504958] [] but task is already holding lock: [ 15.504960] ffff5b4d0e8f1918 (&mtk_subdev->channels_lock){+.+.}-{4:4}, at: mtk_register_device_work_function+0x50/0x1cc [mtk_rpmsg] [ 15.504978] [] which lock already depends on the new lock. [ 15.504980] [] the existing dependency chain (in reverse order) is: [ 15.504982] [] -> #1 (&mtk_subdev->channels_lock){+.+.}-{4:4}: [ 15.504990] lock_acquire+0x68/0x84 [ 15.504999] __mutex_lock+0xa4/0x3e0 [ 15.505007] mutex_lock_nested+0x40/0x70 [ 15.505012] mtk_rpmsg_ns_cb+0xe4/0x134 [mtk_rpmsg] [ 15.641684] mtk_rpmsg_ipi_handler+0x38/0x64 [mtk_rpmsg] [ 15.641693] scp_ipi_handler+0xbc/0x180 [mtk_scp] [ 15.663905] mt8192_scp_irq_handler+0x44/0xa4 [mtk_scp] [ 15.663915] scp_irq_handler+0x6c/0xa0 [mtk_scp] [ 15.685779] irq_thread_fn+0x34/0xa0 [ 15.685785] irq_thread+0x18c/0x240 [ 15.685789] kthread+0x104/0x110 [ 15.709579] ret_from_fork+0x10/0x20 [ 15.709586] [] -> #0 (&scp->ipi_desc[i].lock){+.+.}-{4:4}: [ 15.731271] __lock_acquire+0x11e4/0x1910 [ 15.740367] lock_acquire.part.0+0xd8/0x220 [ 15.749813] lock_acquire+0x68/0x84 [ 15.757861] __mutex_lock+0xa4/0x3e0 [ 15.766084] mutex_lock_nested+0x40/0x70 [ 15.775006] scp_ipi_lock+0x34/0x50 [mtk_scp_ipi] [ 15.785503] scp_ipi_register+0x40/0xa4 [mtk_scp_ipi] [ 15.796697] scp_register_ipi+0x1c/0x30 [mtk_scp] [ 15.807194] mtk_rpmsg_create_ept+0xa0/0x108 [mtk_rpmsg] [ 15.818912] rpmsg_create_ept+0x44/0x60 [ 15.827660] cros_ec_rpmsg_probe+0x15c/0x1f0 [ 15.837282] rpmsg_dev_probe+0x128/0x1d0 [ 15.846203] really_probe.part.0+0xa4/0x2a0 [ 15.855649] __driver_probe_device+0xa0/0x150 [ 15.865443] driver_probe_device+0x48/0x150 [ 15.877157] __device_attach_driver+0xc0/0x12c [ 15.889359] bus_for_each_drv+0x80/0xe0 [ 15.900330] __device_attach+0xe4/0x190 [ 15.911303] device_initial_probe+0x1c/0x2c [ 15.922969] bus_probe_device+0xa8/0xb0 [ 15.933927] device_add+0x3a8/0x8a0 [ 15.944193] device_register+0x28/0x40 [ 15.954970] rpmsg_register_device+0x5c/0xa0 [ 15.966782] mtk_register_device_work_function+0x148/0x1cc [mtk_rpmsg] [ 15.983146] process_one_work+0x294/0x664 [ 15.994458] worker_thread+0x7c/0x45c [ 16.005069] kthread+0x104/0x110 [ 16.014789] ret_from_fork+0x10/0x20 [ 16.025201] [] other info that might help us debug this: [ 16.047769] Possible unsafe locking scenario: [ 16.063942] CPU0 CPU1 [ 16.075166] ---- ---- [ 16.086376] lock(&mtk_subdev->channels_lock); [ 16.097592] lock(&scp->ipi_desc[i].lock); [ 16.113188] lock(&mtk_subdev->channels_lock); [ 16.129482] lock(&scp->ipi_desc[i].lock); [ 16.140020] [] * DEADLOCK * [ 16.158282] 4 locks held by kworker/0:3/155: [ 16.168978] #0: ffff5b4d00008748 ((wq_completion)events){+.+.}-{0:0}, at: process_one_work+0x1fc/0x664 [ 16.190017] #1: ffff80000953bdc8 ((work_completion)(&mtk_subdev->register_work)){+.+.}-{0:0}, at: process_one_work+0x1fc/0x664 [ 16.215269] #2: ffff5b4d0e8f1918 (&mtk_subdev->channels_lock){+.+.}-{4:4}, at: mtk_register_device_work_function+0x50/0x1cc [mtk_rpmsg] [ 16.242131] #3: ffff5b4d05964190 (&dev->mutex){....}-{4:4}, at: __device_attach+0x44/0x190 To solve this, simply unlock the channels_lock mutex before calling mtk_rpmsg_register_device() and relock it right after, as safety is still ensured by the locking mechanism that happens right after through SCP. Fixes: `7017996951` ("rpmsg: add rpmsg support for mt8183 SCP.") Signed-off-by: AngeloGioacchino Del Regno <angelogioacchino.delregno@collabora.com> Link: https://lore.kernel.org/r/20220525091201.14210-1-angelogioacchino.delregno@collabora.com Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org> Signed-off-by: Sasha Levin <sashal@kernel.org>		History 2022-08-17 15:15:46 +02:00
arch	xen: don't require virtio with grants for non-PV guests	2022-08-17 15:15:41 +02:00
block	block: ensure iov_iter advances for added pages	2022-08-17 15:15:43 +02:00
certs	certs: make system keyring depend on x509 parser	2022-07-24 12:53:55 -07:00
crypto	crypto: s390 - do not depend on CRYPTO_HW for SIMD implementations	2022-07-06 20:04:06 -07:00
Documentation	dt-bindings: mmc: sdhci-msm: Fix issues in yaml bindings	2022-08-17 15:15:30 +02:00
drivers
fs	jbd2: fix assertion 'jh->b_frozen_data == NULL' failure when journal aborted	2022-08-17 15:15:43 +02:00
include	xen: don't require virtio with grants for non-PV guests	2022-08-17 15:15:41 +02:00
init	stack: Declare {randomize_,}kstack_offset to fix Sparse warnings	2022-08-17 15:14:14 +02:00
io_uring	io_uring: Don't require reinitable percpu_ref	2022-08-17 15:14:20 +02:00
ipc	ipc: Free mq_sysctls if ipc namespace creation failed	2022-06-22 17:47:41 -05:00
kernel	wireguard: ratelimiter: use hrtimer in selftest	2022-08-17 15:14:59 +02:00
lib	lib/test_hmm: avoid accessing uninitialized pages	2022-08-17 15:15:20 +02:00
LICENSES	LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers	2021-12-16 14:33:10 +01:00
mm	mm/mmap.c: fix missing call to vm_unacct_memory in mmap_region	2022-08-17 15:15:40 +02:00
net	dccp: put dccp_qpolicy_full() and dccp_qpolicy_push() in the same lock	2022-08-17 15:14:59 +02:00
samples	sample: bpf: xdp_router_ipv4: Allow the kernel to send arp requests	2022-08-17 15:14:25 +02:00
scripts	scripts/gdb: fix 'lx-dmesg' on 32 bits arch	2022-08-17 15:15:36 +02:00
security	selinux: Add boundary check in put_entry()	2022-08-17 15:14:06 +02:00
sound	ASoC: cs35l45: Add endianness flag in snd_soc_component_driver	2022-08-17 15:15:46 +02:00
tools	selftests: kvm: set rax before vmcall	2022-08-17 15:15:41 +02:00
usr	Not a lot of material this cycle. Many singleton patches against various	2022-05-27 11:22:03 -07:00
virt	KVM: Don't set Accessed/Dirty bits for ZERO_PAGE	2022-08-17 15:15:21 +02:00
.clang-format	clang-format: Fix space after for_each macros	2022-05-20 19:27:16 +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: use 'dts' diff driver for dts files	2019-12-04 19:44:11 -08:00
.gitignore	kbuild: split the second line of .mod into .usyms	2022-05-08 03:16:59 +09:00
.mailmap	ARM: SoC fixes for 5.19, part 4	2022-07-27 09:43:07 -07:00
COPYING	COPYING: state that all contributions really are covered by this file	2020-02-10 13:32:20 -08:00
CREDITS	MAINTAINERS: mark ARM/PALM TREO SUPPORT orphan	2022-07-07 15:17:00 +02:00
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	io_uring: move to separate directory	2022-08-17 15:14:20 +02:00
Makefile	io_uring: move to separate directory	2022-08-17 15:14:20 +02:00
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.