a14bf98c04
In current driver, locks can be taken as follows:
- Register access: take a lock on regmap config and then on clock.
- Master clock provider: take a lock on clock and then on regmap config.
This can lead to the circular locking summarized below.
Remove peripheral clock management through regmap framework, and manage
peripheral clock in driver instead. On register access, lock on clock
is taken first, which allows to avoid possible locking issue.
[ 6696.561513] ======================================================
[ 6696.567670] WARNING: possible circular locking dependency detected
[ 6696.573842] 4.19.49 #866 Not tainted
[ 6696.577397] ------------------------------------------------------
[ 6696.583566] pulseaudio/6439 is trying to acquire lock:
[ 6696.588697] 87b0a25b (enable_lock){..-.}, at: clk_enable_lock+0x64/0x128
[ 6696.595377]
[ 6696.595377] but task is already holding lock:
[ 6696.601197] d858f825 (stm32_sai_sub:1342:(sai->regmap_config)->lock){....}
...
[ 6696.812513] Possible unsafe locking scenario:
[ 6696.812513]
[ 6696.818418] CPU0 CPU1
[ 6696.822935] ---- ----
[ 6696.827451] lock(stm32_sai_sub:1342:(sai->regmap_config)->lock);
[ 6696.833618] lock(enable_lock);
[ 6696.839350] lock(stm32_sai_sub:1342:
(sai->regmap_config)->lock);
[ 6696.848035] lock(enable_lock);
Fixes:
|
||
|---|---|---|
| Documentation | ||
| LICENSES | ||
| arch | ||
| block | ||
| certs | ||
| crypto | ||
| drivers | ||
| fs | ||
| include | ||
| init | ||
| ipc | ||
| kernel | ||
| lib | ||
| mm | ||
| net | ||
| samples | ||
| scripts | ||
| security | ||
| sound | ||
| tools | ||
| usr | ||
| virt | ||
| .clang-format | ||
| .cocciconfig | ||
| .get_maintainer.ignore | ||
| .gitattributes | ||
| .gitignore | ||
| .mailmap | ||
| COPYING | ||
| CREDITS | ||
| Kbuild | ||
| Kconfig | ||
| MAINTAINERS | ||
| Makefile | ||
| 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.