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Tzung-Bi Shih 08df0d9a00
ASoC: max98090: revert "ASoC: max98090: fix lockdep warning" 
Commit 2dc98af62c ("ASoC: max98090: fix lockdep warning") introduced
a helpful-less small lock: shdn_lock.  Reverts the commit.

Reasons:

1. Lockdep should not be happy by either the original or current code.
From lockdep's point of view, there is a lock inversion anyway.

Let d = dapm_mutex, c = controls_rwsem, s = shdn_lock,

From the reported calling stack: lock acquisition order of
snd_soc_register_card() is: d -> c.
> snd_ctl_add_replace+0x3c/0x84
> dapm_create_or_share_kcontrol+0x24c/0x2e0
> snd_soc_dapm_new_widgets+0x308/0x594
> snd_soc_bind_card+0x80c/0xad4
> devm_snd_soc_register_card+0x34/0x6c

If calling snd_soc_dapm_put_enum_double() in kcontrol's put (e.g.
SOC_DAPM_ENUM_EXT), lock acquisition order is: c -> d.  Note that,
snd_soc_dapm_put_enum_double() acquires d.

The possible lock inversion is always there if registering sound card
and putting mixer control happen at the same time.  In fact, it never
happens because the control device don't show up to the userspace until
the sound card build success.

Commit 2dc98af62c ("ASoC: max98090: fix lockdep warning") changes the
order to: c -> s -> d.  The lock inversion is still there.

2. Commit 62d5ae4caf ("ASoC: max98090: save and restore SHDN when
changing sensitive registers SHDN bit") designed to use dapm_mutex to
protect SHDN bit.  Use a separate lock breaks the protection.

DAPM changes SHDN bit automatically when it finds the path.  Thus, any
code wants to change the SHDN bit, need to acquire the dapm_mutex first.

> SND_SOC_DAPM_SUPPLY("SHDN", M98090_REG_DEVICE_SHUTDOWN,
>        M98090_SHDNN_SHIFT, 0, NULL, 0),

Fixes: 2dc98af62c ("ASoC: max98090: fix lockdep warning")
Signed-off-by: Tzung-Bi Shih <tzungbi@google.com>
Link: https://lore.kernel.org/r/20200117073814.82441-2-tzungbi@google.com
Signed-off-by: Mark Brown <broonie@kernel.org>
2020-01-21 17:14:33 +00:00
arch ARM fixes for 5.5-rc: 2019-12-06 16:12:39 -08:00
block block: fix memleak of bio integrity data 2019-12-05 11:38:36 -07:00
certs certs: Add wrapper function to check blacklisted binary hash 2019-11-12 12:25:50 +11:00
crypto Merge git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2019-11-25 19:49:58 -08:00
Documentation ASoC: dt-bindings: fsl_asrc: add compatible string for imx8qm & imx8qxp 2020-01-14 16:07:11 +00:00
drivers regulator: add regulator_equal() 2020-01-14 15:52:48 +00:00
fs 9 cifs/smb3 fixes: two timestamp fixes, one oops fix (during oplock break) for stable, two fixes found in multichannel testing, two fixes for file create when using modeforsid mount parm 2019-12-08 12:12:18 -08:00
include ASoC: soc-core: remove bus_control 2020-01-21 17:07:08 +00:00
init init/Kconfig: fix indentation 2019-12-04 19:44:13 -08:00
ipc y2038: remove CONFIG_64BIT_TIME 2019-11-15 14:38:27 +01:00
kernel Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-08 13:28:11 -08:00
lib lib/: fix Kconfig indentation 2019-12-07 11:00:19 -08:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'akpm' (patches from Andrew) 2019-12-05 09:46:26 -08:00
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-08 13:28:11 -08:00
samples samples/bpf: Fix broken xdp_rxq_info due to map order assumptions 2019-12-04 17:54:15 -08:00
scripts Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-08 13:28:11 -08:00
security + Features 2019-12-03 12:51:35 -08:00
sound ASoC: max98090: revert "ASoC: max98090: fix lockdep warning" 2020-01-21 17:14:33 +00:00
tools Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net 2019-12-08 13:28:11 -08:00
usr arch: sembuf.h: make uapi asm/sembuf.h self-contained 2019-12-04 19:44:14 -08:00
virt KVM: Fix jump label out_free_* in kvm_init() 2019-11-23 11:29:17 +01:00
.clang-format clang-format: Update with the latest for_each macro list 2019-08-31 10:00:51 +02:00
.cocciconfig
.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 modpost: dump missing namespaces into a single modules.nsdeps file 2019-11-11 20:10:01 +09:00
.mailmap Merge mainline/master into arm/fixes 2019-12-05 13:18:54 -08:00
COPYING
CREDITS Linux 5.4-rc4 2019-10-29 04:43:29 -06:00
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 2019-12-08 13:28:11 -08:00
Makefile Linux 5.5-rc1 2019-12-08 14:57:55 -08:00
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.