cb88f7f51b
Currently, cblist_init_generic() holds a raw spinlock when invoking INIT_WORK(). This fails in kernels built with CONFIG_DEBUG_OBJECTS=y due to memory allocation being forbidden while holding a raw spinlock. But the only reason for holding the raw spinlock is to synchronize with early boot calls to call_rcu_tasks(), call_rcu_tasks_rude, and, last but not least, call_rcu_tasks_trace(). These calls also invoke cblist_init_generic() in order to support early boot queueing of callbacks. Except that there are no early boot calls to either of these three functions, and the BPF guys confirm that they have no plans to add any such calls. This commit therefore removes the synchronization and adds a WARN_ON_ONCE() to catch the case of now-prohibited early boot RCU Tasks callback queueing. If early boot queueing is needed, an "initialized" flag may be added to the rcu_tasks structure. Then queueing a callback before this flag is set would initialize the callback list (if needed) and queue the callback. The decision as to where to queue the callback given the possibility of non-zero boot CPUs is left as an exercise for the reader. Reported-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.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.