45e3d5a2af
On PREEMPT_RT the locks are quite different so they can't be tested as it is done below. The alternative is to test for the waitlock within rtmutex. This is the bare minimun to get it compiled. Problems which exist on PREEMP_RT: - none of the locks (spinlock_t, rwlock_t, mutex_t, rw_semaphore) may be acquired with disabled preemption or interrupts. If I read the code correct the it is possible to acquire a mutex_t with disabled interrupts. I don't know how to obtain a lock pointer. Technically they are not exported to userland. - memory can not be allocated with disabled preemption or interrupts even with GFP_ATOMIC. Link: https://lkml.kernel.org/r/20201028181041.xyeothhkouc3p4md@linutronix.de Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Cc: Konstantin Khlebnikov <khlebnikov@yandex-team.ru> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: 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.