mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
synced 2026-04-29 01:09:33 -04:00
6b57b15abe
This commit fixes two issues:
1. The lockdep warning reported by Dong Aisheng <dongas86@gmail.com> [1].
It is a warning about a cycle (dpm_list_mtx --> kn->active#3 --> fw_lock)
that was introduced when device-link devices were added to expose device
link information in sysfs.
The patch that "introduced" this cycle can't be reverted because it's fixes
a real SRCU issue and also ensures that the device-link device is deleted
as soon as the device-link is deleted. This is important to avoid sysfs
name collisions if the device-link is create again immediately (this can
happen a lot with deferred probing).
2. Inconsistency in grabbing device_pm_lock() during device link deletion
Some device link deletion code paths grab device_pm_lock(), while others
don't. The device_pm_lock() is grabbed during device_link_add() because it
checks if the supplier is in the dpm_list and also reorders the dpm_list.
However, when a device link is deleted, it does not do either of those and
therefore device_pm_lock() is not necessary. Dropping the device_pm_lock()
in all the device link deletion paths removes the inconsistency in locking.
Thanks to Stephen Boyd for helping me understand the lockdep splat.
Fixes: 843e600b8a ("driver core: Fix sleeping in invalid context during device link deletion")
[1] - https://lore.kernel.org/lkml/CAA+hA=S4eAreb7vo69LAXSk2t5=DEKNxHaiY1wSpk4xTp9urLg@mail.gmail.com/
Reported-by: Dong Aisheng <dongas86@gmail.com>
Signed-off-by: Saravana Kannan <saravanak@google.com>
Tested-by: Peng Fan <peng.fan@nxp.com>
Link: https://lore.kernel.org/r/20200901184445.1736658-1-saravanak@google.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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.