e7b20d9796
cgrp->root->release_agent_path is protected by both cgroup_mutex and release_agent_path_lock and readers can hold either one. The dual-locking scheme was introduced while breaking a locking dependency issue around cgroup_mutex but doesn't make sense anymore given that the only remaining reader which uses cgroup_mutex is cgroup1_releaes_agent(). This patch updates cgroup1_release_agent() to use release_agent_path_lock so that release_agent_path is always protected only by release_agent_path_lock. While at it, convert strlen() based empty string checks to direct tests on the first character as suggested by Linus. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Linus Torvalds <torvalds@linux-foundation.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.