tree c7de61e6672c624905c7e30370da163ea5a7d354
parent 7576611e97b51a073a294bdc6d4d8d1fb0a8b86f
author Sebastian Andrzej Siewior <bigeasy@linutronix.de> 1660901086 +0200
committer Mark Gross <markgross@kernel.org> 1666906436 -0700

workqueue: Convert the pool::lock and wq_mayday_lock to raw_spinlock_t

Upstream commit a9b8a985294debae00f6c087dfec8c384d30a3b9

The workqueue code has it's internal spinlocks (pool::lock), which
are acquired on most workqueue operations. These spinlocks are
converted to 'sleeping' spinlocks on a RT-kernel.

Workqueue functions can be invoked from contexts which are truly atomic
even on a PREEMPT_RT enabled kernel. Taking sleeping locks from such
contexts is forbidden.

The pool::lock hold times are bound and the code sections are
relatively short, which allows to convert pool::lock and as a
consequence wq_mayday_lock to raw spinlocks which are truly spinning
locks even on a PREEMPT_RT kernel.

With the previous conversion of the manager waitqueue to a simple
waitqueue workqueues are now fully RT compliant.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Reviewed-by: Lai Jiangshan <jiangshanlai@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Mark Gross <markgross@kernel.org>