On 2020-03-25 13:27:49 [+0100], Thomas Gleixner wrote: > The documentation of rw_semaphores is wrong as it claims that the non-owner > reader release is not supported by RT. That's just history biased memory > distortion. > > Split the 'Owner semantics' section up and add separate sections for > semaphore and rw_semaphore to reflect reality. > > Aside of that the following updates are done: > > - Add pseudo code to document the spinlock state preserving mechanism on > PREEMPT_RT > > - Wordsmith the bitspinlock and lock nesting sections > > Co-developed-by: Paul McKenney <paul...@kernel.org> > Signed-off-by: Paul McKenney <paul...@kernel.org> > Signed-off-by: Thomas Gleixner <t...@linutronix.de> Acked-by: Sebastian Andrzej Siewior <bige...@linutronix.de>
> --- a/Documentation/locking/locktypes.rst > +++ b/Documentation/locking/locktypes.rst … > +rw_semaphore > +============ > + > +rw_semaphore is a multiple readers and single writer lock mechanism. > + > +On non-PREEMPT_RT kernels the implementation is fair, thus preventing > +writer starvation. > + > +rw_semaphore complies by default with the strict owner semantics, but there > +exist special-purpose interfaces that allow non-owner release for readers. > +These work independent of the kernel configuration. This reads funny, could be my English. "This works independent …" maybe? Sebastian
